THE COMPARATIVE ACTION OF ACARICIDES ON THE TWO-SPOTTED

SPIDER MITE, TETRANYCHUS TELARIUS (L.),

(ACARINA: TETRANYCHIDAE)

By

Marcel Mailloux

A THESIS

Subrnitted to the Faculty of Graduate Studies and Research, McGill University, in partial fulfil­ment of the requirements for the degree of

MASTER OF SCIENCE

October, 1960

TABLE OF CONTENTS

Page

I. INTRODUCTION • • . . . . • . . . . . . • . . . . . . . . . . . . • . • . . . • . . • . • • 1

II. LITERATURE REVIEW' • . . . • . . • • • . • • • • • • • . . • . . • • • . . . . . . • • 3

III. MATERIALS, EQUIPMENT, METHODS AND PROCEDURE •••.••••• 22

A. BIOLOGICAL MATERIAL ••••••••••••.•••••.•••.••.•.• 22

1. Rearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2. Handling and collecting •••••••••••.•••••••••• 22

3. Selection and rearing of host plants ••••••••• 23

B. EQUIPMENT AND METHODS OF APPLICATION ••..•..••••• 24

C. CHEMICAL MATERIALS TESTED •••.•••••••••.••••••••• 26

D. CRITERIA USED IN DISTINGUISHING DEAD FROM LIVE MITES AND EGGS • • • • • • • • • • . . • • • . • • . • • • • • • • • • 3 2

E. TREA T1v!ENT • • • • • • . . • • • • • • • • • • • • • • . • . • • • • • • • . • • • • • • 3 3

1. Immediate-contact effect tests ••••••••••••••• 33

a. Adults • . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . • 33

b. Eggs • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5

c. Immatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

2. Residual effect tests . . . . . . . . . . . . . . . . . . . . . . . . 36

IV. RESULTS AND DISCUSSION •••••••••••••••.••••.•••••••• 37

A. EFFECT OF KELTHANE EC ON T.TELARIUS (1.) •••••••• 37

B. EFFECT OF KELTHANE WON T.TELARIUS (L.) ••••••••• 39

TABLE OF CONTENTS (cont'd}

Page

C. EFli'ECT OF TEDION WON T.TELARIUS (L.) •••••••••• 42

D. EFFECT OF CHLOROBENZILATE WON T.TELARIUS (L.) • 44

E. EFFECT OF ARAHITE WON T.TELARIUS (L.) ••••••••• 47

F. EFFECT OF DIBROM 8 ON !•TELARIUS (L.) ••·••••••• 49

G. EFFECT OF OVOTRAN WON T.TELARIUS (L.) ••••••••• 51

H. IMr-'IEDIATE-CONTACT EFFECTS OF DINITE E AND MALATHION EON T.TELARIUS (L.) •••••••••••••••• 53

I. I~ŒDIATE-CONTACT EFFECTS OF TRITHION W, ETHION W AND MALATHION WON !•TELARIUS (L.) •••••••••• 55

J. ~'IEDIATE-CONTACT EFFECTS OF MITOX W, THIODAN W AND KARATHANE WON T.TELARIUS (L.) •••••••••••• 57

K. EFFECTS OF SYSTEMIC COMPOUNDS ON T.TELARIUS (L.) 60

L. IMMEDIATE-CONTACT EFFECTS OF SELECTED ORGANIC MOLECULES ON T.TELARIUS (L.) •••••••••••••••••• 66

M. OBSERVATIONS • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 72

1. Chlorinated compounds ••••••••••••••••••••••• 72

2. Organic phosphorous and sulfur compounds •••• 74

3. Dinitro compounds •••••••••••••••••••••.••••• ?6

V. SUMMARY AND CONCLUSIONS •••••••••••••••••••••••••• 78

VI. ACKNOVJLEDGEMENTS • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 80

VII. LITERATURE CITED • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

PLATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-VI

I. INTRODUCTION

Phytophagous mites have recently become increasin~ly

important economie pests in many parts of the world. This

increase in importance is considered by many as due to the

widespread use of insecticides which have killed the pre­

dators that previous1y kept mites under control. It has

created a need for specifie acaricides of re1ative1y 1ow

toxicity to insects. Many such have appeared on the market.

Sorne have been adequate1y tested, many have not.

Workers have often uti1ized on1y the adu1t mite as the

test animal in the evaluation of these acaricides. It has,

however, been demonstrated (Ebe1ing and Pence, 1954; Me1tzer,

1955) that it is mis1eading to evaluate acaricides on the

basis of their effectiveness against a single developmental

stageo

The different developmental stages of mites vary great­

ly in their susceptibility to acaricides. Experimenta have

shown that a given acaricide may be highly toxic to the adult

stage but not to the egg stage, the latter being the limiting

factor in its practical usefulness. On the other hand, a

second acaricide may be less toxic to adults than the first,

but sufficiently effective against both stages to be of

practica1 value.

The term action is used in this paper in its broadest

sense rather than in the more 1imited sense of the primary

biochemical or physio1ogica1 action on a specifie system

resu1ting in a toxic effect.

Since the works of Ebeling and Pence (1954) and

Meltzer (1955) many new acaricides have been developed and

apparently no comprehensive investigation of the relative

susceptibility to these acaricides of the deve1opmenta1

stages has been reported in the literature.

2.

Furthermore, no study seems to have been undertaken with

as many acaricides as possible in order to compare any two of

the acaricides tested under the same conditions of experi­

mental design.

The objective of this study was to compare the effective­

ness of acaricides against the different developmental stages

of the two-spotted spider mite, Tetranychus telarius (L.).

II. LITERATURE REVIEW

Steer (1937) reported that the number of pesticides

requiring consideration has greatly increased in recent

years. From such a host of potential insecticides the few

worthy of close investigation can be sorted out only by

rapid and reliable laboratory methods of testing. He, there­

fore, described such a method for the testing of acaricides

on the winter eggs of the red-spider mite.

Shoots bearing eggs were eut and kept in the insectary

or laboratory with the eut ends immersed in wet sand or

water. These shoots were dipped into the spray fluid to be

tested and then drained. From these shoots, random samples

of !" to 1" long were eut off and placed in glass tubes

3.

fitted with drilled corks. The mites hatched out but were

prevented from leaving the tubes by a piece of closely woven

material which, however, allowed sufficient ventilation to

prevent mould gro~1ing on the eut shoots. After the incubation

period, hatched and unhatched eggs were counted.

Kearns and Flint (1937} tested many derivatives of cyclo­

hexylamine against the two-spotted spider mite, T.telarius

(L.) in order to obtain data regarding the relationship of

physical properties and molecular structure to toxicity. At

that time no accurate method for conducting red spider tests

was available and the writers could not improvise any more

satisfactory method than spraying infested rose plants.

However, particular care was taken in the selection of

material to obtain plants with a similar degree of in­

festation and with the greater number of mites in the mature

stage. By counting the dead and live spiders on all leaves

and parts of treated plants, and by replicating each concen­

tration at least 5 times, these two workers found that fairly

accurate evaluation could be made.

Kearns and Compton (1938) carried out laboratory tests

on T.telarius (L.) with a cyclohexylamine compound that showed

in previous experiments, good active insecticidal properties.

These tests were conducted on the motile stages of red spider

infesting Talisman variety of rose. Excised infested leaves

were sprayed under a pressure of 10 p.s.i., by means of an

atomizer operated by an air compresser. The treated leaves

were kept in turgid condition for a period of 48 hours by

the following method. A bent piece of glass tubing 6 inches

long with an inside diameter of 4 millimeters, was hung over

the edge of a drinking glass which was partially filled

with water. The water was brought into the tube by a slight

suction. The tip end of the stem of a treated leaf was

inserted into the tube. A ring of petroleum jelly was

immediately made around the stem at the point where it

entered the tube, to keep water from running along the stem

and onto the leaf. The mortality counts were made from là

to 24 hours after spraying.

King and Frear (1943) undertook laboratory tests with

8 N-Heterocyclic compounds related to nicotine in the search

for new organic insecticides. Tetranychus telarius (L.) was

chosen as the test animal due to its ease of rearing and its

economie importance. The sprays were applied from an atom­

izer-type air-brush, operated by a DeVilbiss air compresser

at a constant spraying pressure of 16 pounds and were sprayed

into a wooden chamber equipped with an exhaust fan at the

5.

back and a turntable at the rear center. Garden beans of the

Black Wax Pencil pod variety were grown in greenhouse flats

until the seed-leaves were well-developed and were then

transplanted into 2-inch pots. The following day the plants

were inoculated by laying on them heavily infested leaves.

Twenty-four hours later, a plant was placed on the turntable

and the spray applied from a distance of 30 inches, for 30

seconds. The number of dead and live adult mites were counted

under a microscope binocular, 24 hours after spraying.

Dickinson (1944) considered that testing the residual

value of organic compounds is one of the most important parts

of investigations on their use as insecticides. !.telarius

(L.) was used for the test because of its short life history

and the ease with which a stock is reared. Henderson Lima

bean gro\~ singly in 3-inch pots has been chosen as the host

plant. Infestation with 5 adult mites per leaf occurred at

various intervals after spraying. Only the primary leaves

were used and the mites were confined to a definite area by

means of a sticky barrier. The mites were removed from the

plants after 48 hours when mortality records were taken and

5 days later, when all the eggs deposited had hatched if the

insecticide had had no inhibitory action, records were made.

Siegler (1947) devised a method to reduce the work in­

volved in taking mortality records of the two-spotted spider

mite in tests of acaricides. He reared the test animal on

bush lima beans. Disks were eut off,with a cork borer,from

leaves suitably infested. These leaf disks were placed in

a petri dish and then removed, one at a time, with forceps

6.

and immersed in the test material for 3 seconds. After treat­

ment, the disks were returned to the petri dish, which was

provided with moist cotton and held until examination.

Weinman and Decker (1947) carried out laboratory tests

on the common red spider, Tetranychus telarius {L.) living

on Better Times roses. These tests were made in the hope of

finding out if modifications of the pentachlorophenol mole­

cule would result in one or more compounds which would retain

high toxicity to this mite. Excised leaves were sprayed with

solutions of the 25 tested compounds dissolved in 65% acetone

and 35% distilled water plus Santomerse D. After having been

sprayed, the leaves were kept fresh for 24 to 48 hours by

placing the stems in capillary tubes filled with water,

according to the method of Kearns and Compton (1938).

The counts were made 24 hours after spraying on large motile

stages only. The effectiveness of test solutions against eggs

and resting stages was measured by the relative numbers of

live larvae and individuals newly emerged from resting stages

on the sprayed leaves.

Kenaga and Hummer (1949) and Kenaga (1949, 1949a) devised

laboratory experiments on different materials to illustrate

the effect of various ring substitutions on the degree and

specificity of toxicity to the two-spotted spider mite.

Twenty-two substituted phenyl benzene sulfonates, 24 analogues

of bis (4-chlorophenoxy) methane and 20 phenyl benzoates were

used respectively in the 3 tests. All these materials were

tested against the egg and adult stages of T.telarius (L.).

Cranberry beans with primary leaves only were dipped moment­

arily in the insecticidal dispersion. Mortality counts were

taken 6 days after application of the insecticide and cor­

rected for natural mortality. A range of concentrations

was tested to find out the lowest one causing 95 to lOO%

mortality.

Armstrong (1950a) undertook laboratory and greenhouse

tests of acaricides on the two-spotted spider mite. A D~

Vilbiss motor-driven, compressed air paint-sprayer was used

for spraying. This paint sprayed had a nozzle that produced

a fine, even spray under an air pressure of approximately

20 pounds per square inch. Scarlet runner bean plants with

2 leaves only in 3- inch pots were thoroughly sprayed from

all sides to the point of run-off. In these experiments,

the residual toxicity of the newer acaricides was sought. At

intervals over a period of 14 days, heavily infested leaves

were placed on the sprayed plants, two plants being used at

8.

a time. The source leaves were removed in 24 hours, the mites

having transferred to the sprayed plants. Mortality counts

were made 7, 14 and 21 days after the mites were transferred

to the sprayed foliage, by counting live and dead mites with

the aid of a stereoscopie microscope.

Eaton and Davies (1950) carried out laboratory tests

of series of organo-phosphorous compounds on the winter and

summer eggs and adults of the European red mite, P.ulmi

(Koch). The winter eggs were obtained by allowing an in­

festation to develop in the greenhouse on potted apple seed­

lings during late summer. The next spring, tests were made by

selecting egg-bearing shoots, treating by immersion for 10

seconds and allowing to drain and dry after inserting the

lower ènds of the shoots in trays of moist sand. After, they

followed the method described earlier under Steer (1937).

According to these authors, previous workers do not

appear to have described methods for the large-scale quan­

titative testing of acaricides against the summer eggs of

f.ulmi {Koch). Infested apple leaves were collected in the

field and those bearing about lOO eggs were selected for

tests. They removed all active stages and counted the re­

maining eggs. Leaves were dipped for 10 seconds in the

washes. After draining and drying, the petioles were vase­

lined and inserted into water, and the plants retained until

the time of hatching. About 10 to 12 days later, counts of

unhatched eggs were made.

In adulticidal tests, leaves bearing 20 to 50 females

were dipped in the test solutions, allowed to drain and dry, • Il Il the pet~oles ~vaselined and then placed in moist chambers for

9.

24 to 48 hours. After which counts of dead and living females

were made under a microscope.

Eaton and Davies (1950a) investigated in the laboratory

the acaricidal activity of 90 synthetic organic compounds.

They sought relationships between molecular structure and

acaricidal activity. These tests were carried out exactly as

described above on the 3 groups of stages of the Fruit-tree

red spider mite.

Lochner (1951) reported that the considerable increase

in importance of !•bimaculatus Harvey and the lack of control

with the recommended measures have contributed greatly in the

conduct of acaricide tests against it. Laboratorytests were

carried out with about 11 different materials which were

applied as dusts and sprays to small infested leaf-disks

in petri dishes and tested against the adults and npmphs.

The dusts were applied by the bell-jar method in which the

material is blown through 4 vertical tubes projecting up­

wards •. The sprays were applied with the aid of a settling

to~1er equipment. The ovicidal effect of the se products was

determined by a dipping method in which leaves bearing eggs

were dipped in the solution. The tests were carried out

at constant temperature and humidity.

10.

Read and Wain (1951) undertook acaricidal tests to pro­

vide information on the ovicidal action of 18 phenyltrichlo­

romethylcarbinols or their esters and to investigate their

value for the practical control of the pest. These tests

were carried out against the eggs of the two-spotted spider

mite. Disks of pansy leaves bearing 30 to 80 eggs in all

stages of development were submerged in suspensions of the

test materials for 10 seconds, drained and kept for at 1east

14 days at a temperature of 19°C. Five disks were used

for each of the 4 concentrationsœsted. After drying, each

disk was stuck with gum arabie to a microscope s1ide and

surrounded by a band of petro1eum je11y. The eggs were

counted immediate1y after immersion and al1 1arval and adult

stages ki11ed with a need1e. After the incubation period,

the observations were made with the aid of a binocular

microscope by determining the number of nymphs in the band

of petroleum jelly.

Kirby and McKinlay (1951), in a series of laboratory

tests, used the method described by Eaton and Davies (1950)

11.

for testing acaricides against summer forms of f.ulmi (Koch).

However, they found the ovicidal method too tedious and

shortened it in adopting the method devised by Siegler (1947)

which consists of cutting small leaf-discs from leaves bear­

ing eggs.

Gaines et al (1952) placed approximately 25 mites on

clean, potted cotton seedlings 24 hours before spraying.

Sprays were applied from above, with 35 lb pressure, to re­

volving plants. Six plants were treated with each dosage.

Four to eight dosages, involving the treatment of 1500 or

more mites, were required to establish a dosage mortality

regression. The numbers of live and dead mites were re­

corded daily for 5 consecutive days following treatment.

Hintz (1953) claimed that the egg of the European red

mite is the most difficult stage to kill. He, therefore,

devised experiments for tests against winter and summer eggs

of this mite. He tested 11 formulations on winter eggs and

13 on summer eggs. The acaricides used included five organic

phosphates, two sulfonates, a sulfone and a sulfite. A car­

binol and a dinitro were also used. Tests on winter eggs were

made with twig segments of a Grimes apple tree, bearing a

number of counted eggs. These segments were fastened to

cardboard squares in an upright position. The acaricides

were then applied with an atomizer sprayer until the twigs

were thoroughly wetted. After the application of spray

materials, the eggs were incubated in an open insectary.

12.

A few days before hatching, a ring of tanglefoot is: applied

around the base of the twigs and after incubation, counts of

hatched mites were made. Against the sumrner eggs, a dipping

technique was used. In someœsts, whole apple leaves were

dipped in suspensions or solutions of the toxicant. In other

tests, sections of leaves bearing eggs were affixed to a

microscope slide or squares of cardboard. Poison was applied

to these combinations and counts were made after a period

long enough for incubation.

Kirby and Tew (1953) undertook laboratory tests, with

g chlorinated phenylbenzene sulphonates towards the winter

eggs of P.ulmi (Koch). They used the same techniques as

described earlier under Eaton and Davies (1950) and corrected

the percentage mortalities by Abbott's formula.

Ebeling and Pence (1953) carried out laboratory tests

with 7 acaricides in the purpose of finding the influence

of formulation on effectiveness. The writers claimed that

individual leaves lend themselves more satisfactorily to

treatments by means of a settling tower than do potted plants.

A wet cotton in a petri dish was covered by paper towelling

eut to fit the dish. A Henderson lima bean leaf, dorsal

surface down, was placed on the wet towelling and pressed

down so as to adhere to the towelling along the edges.

The mites were treated by one of three methods: topical,

topical-residue and residue. In each one, 25 adult mites

were transferred by means of a small brush to the under-

13.

side of the leaf. The wet cotton kept the leaves fresh for

the 48-hour period between treatment and counts while the

paper towelling prevented mites from escaping from the leaves.

For the three methods, paper dises with leaves adher­

ing to them were placed in a settling tower for treatment

with a mist during a period of 3 minutes. In the first method,

immediately after spraying, mites were transferred to another

unsprayed leaf in order to see the effect of the topical

treatment alone. In the second method, the mites remained

on the leaves on which they were treated. In the third

method, the leaves were treated first and infested after.

They also used a laboratory spray equipment made on the same

principle as the settling tower but with a discharge orifice

much larger. The same method just described was used but

the spraying time was only 3 seconds.

In 1954, Ebeling and Pence undertook another series of

laboratory tests but with 16 different acaricides. The

purpose of this study was to find out the susceptibility

to acaricides of T.telarius (L.) in the egg, larval and

adult stages. The same procedure as described earlier

14.

(Ebe1ing and Pence, 1953) has been fo11owed throughout these

tests. However, instead of using on1y the adu1t stage, their

studies were carried out on the 1arva1 and the egg stages.

A1so, the treatments were made on1y with the sett1ing tower.

Against the adults, only the residual method mentioned above

was used. In ovicidal tests, 10 adult females were allowed

to deposit eggs for a period of 24 hours on bean leaves

resting on wet cotton covered with paper towelling. The

mites were then discarded and the leaves bearing eggs were

treated in the settling tower. They were placed in a room

with a temperature varying from 80° to B5°F. to hasten the

incubation period. Counts were made 4 days after treatment.

In tests with larvae, 20 adult females were placed on

a leaf and allowed to lay eggs for a period of 5 or 6 days

by which time the eggs have hatched. The bean leaves were

eut in half and a half-leaf was placed on a bean leaf that had

been treated in the settling tower and placed on wet cotton.

Within 24 hours, the half-leaf had wilted and the larvae had

craw1ed onto the treated 1eaf. The recording of data was

made 48 hours later. In all those experiments, dosage-mort­

ality regressions were determined for adults, 1arvae and eggs.

Armstrong et al (1954) designed greenhouse experiments

for a comparative study of three acaricides, notably Elimite,

Ovotran and CPBS. The same method and procedure as described

under Armstrong (1950a) was used in these tests. Furthermore,

15.

they carried out tests on the eggs, immatures and adults of the

two-spotted spider mite to determine the immediate toxicity

of the tested acaricides. In ovicidal tests, eggs were ob­

tained by placing 10 females per leaf, then after 48 hours, the

females were destroyed and the sprays immediately applied.

Records were taken 8 days later.

To obtain larvae for the tests on immatures, 15 adult

females were placed on each leaf and removed 24 hours later.

The resulting eggs hatched in approximately 5 to 6 days and

sprays were applied a few days later when the mites were in

the larval and protonymphal stages. Mortality counts were

made 3 days later.

In tests against adults, a nearly pure culture of adult

mites was secured by placing heavily infested old bean plants

next to uninfested ones so that the foliage intermingled.

A day later, the new plants had become well infested. The

mites on the uppermost leaves were mostly adults. These leaves

were eut off and placed on the test plants to which the mites

moved as the eut leaves wilted. The test plants were sprayed

24 hours later and mortality counts recorded 3 days after

treatment.

Kirby and Read (1954) conducted laboratory experiments

towards the eggs of T.telarius (L.) to find out the ovicidal

toxicity of phenyl benzene sulphonate and 8 chlorinated deriv­

atives. The same biological method as the one described

16.

earlier under Read and Wain (1951} was used. Leaf-permeation

studies of PBS, CPBS and CPCBS were carried out on summer

eggs of the fruit-tree red spider mite. Four apple leaves,

each bearing about 200-600 eggs on the lower surface, were

painted with the suspension on the upper surface only, using

a small camel hair brush. The leaves were kept in 4-inch

petri dishes until final counts on the 18th day after

treatment.

Huisman et al (1955} carried out experiments with four

compounds on T.urticae Koch on bean plants (Phaseolus}.

Potted bean plants with or without eggs were dipped in emul­

sions containing the active material. After the plants

without eggs had dried, these were infested with adult

females to obtain eggs on the dry deposit. Two or three

days later, the adults were discarded. Leaf penetration of

"Tedion" was evaluated in treating the upper side of a bean

leaf and infesting the underside with mites.

Jacks (1955} conducted greenhouse tests in which 41

toxicants were compared with sprays against T.telarius (L.}.

French beans in 6-inch pots growing singly were sprayed

with 80-100 ml. of insecticidal suspensions. Contact and

residual tests were carried out on the eggs and motile

forms.

17.

Meltzer (1955) claimed that the control of the winter

eggs of P.ulmi (Koch) with DNC requires supplementing by

summer sprays. He, therefore, undertook laboratory investi­

gations on 12 acaricides using T.telarius (L.) which resembles

P.ulmi (Koch) in susceptibility to sorne toxicants as the test

animal. These acaricides may be divided into four groups;

phosphorous, dinitro, chlorinated and sulfur compounds. In

tests against the adults, bean plants were dipped in the

suspension and allowed to dry. Adult females 2 to 4 days

old were then confined on the leaves. In tests on the

immature stage, bean plants bearing eggs were dipped or

females were confined on the dry deposits of dipped plants

for 2 to 3 days, the eggs laid being examined after a further

8 days, by which time eggs on untreated plants had given rise

to deutonymphs. The mortality percentages were corrected

according to Abbott's formula.

Brookes et al (1957, 1957a), Clark et al (1957), Brookes

et al (1958, 1958a) and Cranham et al (1958, 195àa) carried

out different series of laboratory screening tests against

the eggs and larvae of T.telarius (L.) with many organic sul­

phides. These experiments were undertaken after other workers,

including Eaton and Davies (1950a) had claimed the need for

materials toxic to the eggs of mites. The tests were made

by dipping eut leaves of French beans each bearing on the

lower surface 30-70 eggs, 1 to 2 days old, for 10 seconds

in 0.1 and sometimes 0.025 per cent dispersions or emulsions

of the chemicals and assessing mortality a week later, two

days after untreated eggs had hatched. The mortality con­

sidered was that of eggs and young mites.

18.

In sorne cases, more precise comparisons of the effective

materials were made by spraying the lower surfaces of the

leaves bearing the eggs in a Potter tower at a rate giving

about 0.3 gm spray per petri dish 9 cm in diameter and

assessing mortality as before.

Green and Jenkins (1958) worked out laboratory tests

against the eggs of f.telarius (L.). Their studies were

carried out with many chlorosubstituted bisphenoxymethanes

and their related compounds at four different concentrations.

A method similar to the one described by Read and Wain (1951)

was used. Dises of 1 cm from French beans and bearing about

50 eggs were immersed for 15 seconds in the test solution.

After, these workers followed exactly the method of Read

and Wain (1951) with the exception that the incubation period

was at 20° to 21°C. The percentage kill was corrected by

Abbott's formula to have a zero control mortality.

Nymphicidal activities of the bis phenylthiomethanes

were also determined by the following method: 14-day old

French bean plants were dipped into 0.02% solutions until

both leaves were thoroughly wet. After being dried, the plants

were infested with leaves from the breeding cages populated

19.

mainly by nymphs. Two days later, the leaves were placed

in petri dishes, surrounded with petroleum jelly and the kill

assessed in the usual way.

The residual ovicidal activities of the most active

bisphenylthiomethanes persisted after spraying was deter­

mined as follows: 14-day old French bean plants were dipped

into a 0.02% solution of the test compound, as described for

the n~phicidal test. The plants were left for 7 days and

then infested. After 72 hours, leaf dises were eut, incu­

bated and the kill determined as described for the ovicidal

tests.

Coulon (1958) carried out laboratory tests with 13

acaricides on the eggs and adult females of T.telarius (L.).

These experiments were made to find.~\erials which would kill

the eggs as well as the motile forms. In ovicidal tests,

bean leaves bearing eggs were sprayed with the solutions of

acaricides. The plants were stored at constant temperature

and humidity for 7 days at which time non-hatched and hatched

eggs were determined. The percent kill was corrected by

Abbott's formula and the LD50 of each material was determined.

In adulticidal tests, bean plants with two leaves only were

sprayed and immediately infested after with 10 adult females

per leaf. The infested plants were stored in the above

mentioned conditions for the eggs,then, 24 hours later, 1

mortality counts were made and the LD50 of each material

was determined.

Meltzer (1958) carried out ovicidal tests on the eggs

20.

of the two-spotted spider mite with four sulfur compounds,

Ovotran, CPBS, chlorbenside and Tedion. These tests were

divided in two series. In the first one, bean plants bearing

eggs were dipped into emulsions of the compounds under consid­

eration. In the ether series, non-infested plants were dipped

and after the plants had been dried, they were infested with

adult females to obtain eggs of the dry deposits. The

latter series was designed to find out the effect of the

materials on the ~ecundity of females and on the developing

eggs in the ovary. Meltzer confined the adult mite in plexi­

glass chambers resting on bean leaves instead of using a

sticky barrier.

Abo-El-Ghar and Boudreaux (1958) tested four different

acaricides on the developmental stages of 5 species of mites.

Two non-phosphate materials were tested, Aramite and sulphur,

and two phosphate ones, Parathion and Phostex. Among the

five species used, T.telarius (L.) was not included. The

following species were used: T.cinnabarinus (Bois-duval),

I.lobosus Boudreaux, I..tumidus Banks, T.gloveri Banks and

I•desertorum Banks. The petri dish method developed by

Ebeling and Pence (1953) was used in tests with adults

nymphs and eggs. Detached green cotton cotyledons of about

2 inches across were used instead of bean leaves. The treat-

21.

ments were made with the aid of a dusting gun similar to the

one described by Ivy (1944). Measured quantities of acari­

cides were calculated on a per acre basis from the area of

the dusting chamber. They determined the LD50 for each

material on the 3 developmental stages of the 5 species of

mite.

Batth and Davidson (1959) carried out laboratory experi­

ments to determine if Tedion causes sterility of the eggs

laid by females of T.telarius (L.) after they have taken up

the chemical orally as well as by contact. Bean plants

grown in 2-inch pots and with only the first two leaves,

were used for experimentation. Mites were confined on the

upper surface of the leaves by a ring of tanglefoot. Pieces

of infested bean leaves were placed within the ringed areas

and treatments were made the following morning. The test

plants were treated with 2 ml of Tedion W by means of a Peet­

Grady DeVilbiss Sprayer, using a pressure of 12.5 pounds per

square inch. The treatments were made within a cylindrical

spray tower. The spray nozzle was directed towards the

plants resting in bottom of this tower. After the spray

had dried the leaves were clipped off and transferred to

petri dish halves. The mites were transferred to uninfested,

unsprayed bean plants about 24 hours after treatments.

Twenty-four hours later these mites were removed and the

deposited eggs observed for viability.

-----------------------------------~---- ---

III. MATERIALS, EQUIPMENT, METHODS AND PROCEDURE

A. BIOLOGICAL MATERIAL

1. Rearing

22.

The two-spotted spider mite, T.telarius (L.) was reared

on red clover, Trifolium pratense L., in the greenhouse. The

infested plants were isolated in a cage to prevent infestation

of other plants. The clover plant was chosen because it lives

for months, when the older leaves are removed from time to time.

The cage was covered with polyethylene in order to let the

light come through. A small opening was left to prevent con­

densation due to transpiration. The mites were prevented from

escape by a sticky barrier deposited along the sides of the door.

The clover plants were collected from a clover field and

transplanted to à-inch pots. When a good number of leaves were

grown, the plants were introduced into the cage to maintain a

good culture of mites all the time.

2. Handling and collecting

For each test, clover leaves were eut off from the stock

plants and examined under a low power stereoscopie microscope.

Mite females of about the same age and vitality were trans­

ferred one by one to the test plants with the aid of a very

fine camel hair brush to reduce handling damage as low as

23.

possible.

The green color forms of T.telarius (L.) were always used

because according to Cole and Fish (1955) the relative sus­

ceptibility of color forms to different acaricides may differ,

depending on the acaricide and the host plant.

3. Selection and rearing of host plants

Many varieties of beans were planted in the greenhouse

to find out their characteristics as regards germination, size

of leaves, height of plants, etc. Among 8 varieties planted,

three only seemed suitable for the tests. They were: one green

pod bush bean, Improved Tendergreen, and two wax pod bush

beans, Pencil Pod and Brittle Wax.

These varieties were preferred because they possess pri­

mary leaves with practically a complete absence of plant hairs

and seerned to grow more easily under greenhouse conditions.

They also withstood manipulations without serious harmful effects.

From these three varieties, Improved Tendergreen was chosen due

to the smaller size of the primary leaves which made them more

suitable for the tests.

The seeds were soaked overnight in water at room temper­

ature and sown thickly in flats of river sand. As soon as the

primary leaves opened (Plate I, Fig.l), the young plants were

transplanted singly to 4-inch pots. These pots contained

5 parts of loam to 2 parts of sand.

Later, as the plants become more rigid, a part of the

stem was covered with a sticky barrier (Plate II, Fig.J) of

24.

white petroleum jelly, to prevent any escape of mites from the

plants and also to prevent invasion by foreign mites. The

central shoot was pinched out as it appeared (Plate II, Fig.4)

and plants with the two primary leaves were used as soon as

they became full•grown.

In immediate-contact effect tests the mean age of plants

from sowing to infestation was 24 days for tests with adults,

25 days for tests with immature forms, and 27 days for tests

with eggs. In residual effect tests the mean age was 25 days

from sowing to treatments.

The plants, both before and after treatment, were watered

each day with a hand sprinkler to prevent any washing of the

leaves because according to Mistric and Martin (1956), the loss

in toxicity due to washing differs with different materials.

B. EQUIPMENT AND METHODS OF APPLICATION

The treatments were made in the laboratory in a special

room equipped for the spraying of plants (Plate III, Fig.5).

The room contained a turntable, a hood, a fan and the spraying

equipment.

The spraying was done with a paint spray gun, type GD

502 (Plate III, Fig.5), manufactured by the DeVilbiss Company,

The gun delivered a very constant amount of solution, no matter

of the concentration used and would operate with a quantity as

25.

little as 150 milliliters.

The valve regulating the ratio of air to liquid volume,

fixed at ! a turn delivered the amount of solution desired for

the tests. The nozzle utilized produced a horizontal or a

vertical spray cone and never clogged with materials. In the

tests undertaken, the nozzle was fixed so that the spray cone

enveloped the plants equally well on all sides.

The spray gun was mounted on a stand (Plate III, Fig.5)

in order to maintain a constant distance of 26 inches between

the centre of the turntable and the nozzle of the spray gun.

However, the angle of the spray cone was changed slightly

according to the height of the plants in order that each plant

might receive the same amount of spray.

The air pressure line from the gun was connected by way

of a reducing valve to an air compresser and the air pressure

was maintained constant at 20 pounds per square inch.

A turntable (Plate III, Fig.5) of 18 inches in diameter

and carrying a single plant was placed inside the hood. The

speed of the turntable was regulated to 30 revolutions per

minute. The table is rotated by a small laboratory motor

with the aid of a belt.

The spraying time used was at 15 seconds throughout the

tests.

Under the above conditions, i.e., an air pressure of

26.

20 p.s.i., the ratio valve fixed at i a turn and the spraying

time at 15 seconds, the quantity of solution applied varied

from 26.5 to 27 milliliters per plant. Although this quantity

seems rather small, it was large enough to wet the plants

thoroughly without run-off.

The eup holding the acaricide solution during treatments

was washed with a detergent and rinsed with distilled water

between each spraying. The spray gun was also washed by filling

the eup with distilled water and spraying through the apparatus.

C. CHEMICAL MATERIALS TESTED

Commercial and chemical names, formulations aupplied,

alternative names and suppliers of the materials tested are

reported in Table I.

Most of the materials have been supplied in their commer­

cial forms whether as wettable powders or emulsifiable con­

centrates. These products have been used as such, being weighed

on a precise balance or measured with a ~ cc tuberculin syringe

as the case may be.

Thereafter, both forms were dispersed in enough distilled

water to obtain the desired concentrations. Consequently, the

concentrations for wettable powders are weight over volume,

while for emulsifiable concentrates they are volume over volume.

All concentrations, designated in tables or elsewhere, are in

27.

parts per million of active ingredients. Usually the solutions

were prepared just prior to treatment.

Systox at 94% and Di-syston at 92% have been supplied in

their technical forms. These two materials were prepared in

the laboratory as 25% emulsifiable concentrates. They were

dissolved in xylene and emulsified by means of an emulsifying

agent, Triton X-161*.

The selected organic molecules ( supplied by the Dominion

Rubber Company) were received in the form of pure chemicals and

are listed in Table XVII. Nearly all of these organic mole­

cules had been previously tested against aphids by Musgrave and

Kukovica (1953, 1955 and 1956) to find out their insecticidal

potency. All but one of the organic molecules supplied poss­

essed at least one sulfur atom in the chain.

Most of these molecules were dissolved in xylene and

emulsified by shaking with Triton X-161. A certain quantity

of material was weighed or measured and put in a small vial.

Thereafter enough solvent, such as xylene, was added to dis­

solve the product entir~ly. The emulsifier, at about 3% of the

formulation, was poured in to make a suitable emulsion. None

of the materials were prepared at a concentration higher than

25%. Two materials proved to be practically non-soluble in

xylene. They were dissolved in acetone at a concentration of

lo% and applied as suspensions.

* Courtesy of Rohm and Haas Co.

Material

Aramite

Chlorobenzilate

Dibrom 8

Dimecron 100( 2 )

Dimite

Di-syston

. Ekatin M 1

TABLE I - List of acaricides tested(l)

Chemical Name

2-(p-tert-butylphenoxy)-iso-propyl 2 1-chloroethyl sulfite

Ethyl 4,4'-dichlorobenzilate

1,2 dibromo 2,2-dichloroethyl dimethyl phosphate

2-chloro-2-diethylcarbamoyl-1-methylvinyldimethyl phosphate

2,2-bis(p-chlorophenyl) ethanol

0,0 diethyl S-2(ethylthio) ethyl phosphorothioate

0,0-dimethyl-S(morpholino-car-baminyl-methyl) dithiophosphate

Formulations supplied

W.P. 15%

\'l. p. 25%

8 lbs/gal. or 64.5% by Wt

Approx.lO lbs/ gal. or lOo%

E.C. 25%

Technical 92%

Approx. lOo%

Al ternative nam es

Cpd 88R

Geigy 338

--

Phosphamidon(3)

DMC, DCPC

Bayer Cpd 19639

--

Supplied by

Naugatuck Chemical Division

Geigy Agr.Chem. Corp.

Ortho-California Spray Chemicals

Ciba Co. Ltd.

Acme Quality Paint s

Chemagro Corp.

Plant Product s Corp •

N 00. •

TABLE I (cont'd) - List of acaricides tested(l)

Material Chemical Name Formulations Alternative supplied names

-Eth ion 0,0,0',0'-tetraethyl S,S'-me- W.P. 25% Nialate

thylene bis phosphorothioate

Exp.Ins.l2880 0,0-dimethyl S-(N-methyl car- s.e. 46% Dimethoate(J) bamoyl-methyl) phosphorodi-thioate

Exp.Ins.l8706( 2 ) 0,0-dimethyl S-(N-ethyl car- s.e. 25% --bamoyl-methyl) phosphorodi-thioate

Karathane (1-methyl-heptyl) dinitro- W.P. 25% Arathane phenyl crotonate (1-methyl- Iscothan heptyl) dinitro-phenol & Mildex related compounds

Kelthane 1,1, bis(4-chlorophenyl)- E.C.l! lb/gal. FW-293 2,2,2-trichloroethanol & W.P. 18.5% DTMC

Malathion(J) OfO-dimethyl dithiophosphate E.c. 57% Mala thon o diethyl mercapto succinate & W.P. 25% Cpd 4049

Supplied by

Niagara Brand Spray

American Cyanamid

American Cyanamid

Rohm &. Haas Co.

Rohm &. Haas Co.

American Cyanamid Stauffer Chemicals

l\)

\.0 •

Mate rial

Mi tox

Ovotran

Phosphaaidon 4

Systox

Tedion

TABLE I {cont 1 d) - List of acaricides tested(l)

Chemical Name

p-chlorobenzyl p-chlorophenyl sul fi de

p-chloropheny1 p-ch1orobenzene sulfonate

1-chloro-1-diethy1carbamoyl-1-propen-2-y1-dimethy1 phosphate

O,O-diethy1 0 (and S)-2-(ethy1thio) ethyl phosphoro­thioate

2,4,4',5-tetrachlorodiphenyl sulfone

Formulations supplied

W.P. 40%

W.P. 5o%

E.c. 4 lbs/gal.

Technical 94%

W.P. 25%

Alternative nam es

Chlorbenside(3) Chlorparacide Chlorsulphacide Elimite

Ovex(3) Chlorfenson K6451 PCPCBS

ML-97 OR-1191

Demet on

Supplied by

Ortho-Ca1ifornia Spray Chemicals

Dow Chemical of Canada

Ortho-California Spray Chemicals

Chemagro Corp.

Stauffer Chemica1s

\A)

0 •

TABLE I (cont'd) - List of acaricides tested(l)

Material

Thiodan

Chemical Name

Hexachlorohexahydro-6,9-me­thanobenzodioxathiepin-3-oxide

Trithion O,O,-diethyl S-(p-chloro­phenyl thiomethyl) phos­phorothioate

Selected organic See: Results - Table XVII molecules

Formulations supplied

W.P. 25%

W.P. 25%

Pure Chemicals

Alternative nam es

Mal ix Niagara 5462

Supplied by

Niagara Brand Spray

Stauffer Chemicals

Dominion Rubber Co.

(1) Adaptations from "Entoma" 13th edition (see Fisher 1960) and Martin (1957).

(2) Information obtained from technical data sheets.

(3) Common names.

\.1.)

...... •

D. CRITERIA USED IN DISTINGUISHING DEAD FROM LIVE

MITES AND EGGS

32.

Mites or eggs killed by different acaricides have a

decidedly different appearance. · This observation will be dis­

cussed in more detail later under results. For instance, mites

killed by sorne materials retain a remarkably life-like appear­

ance and posture (Plate V, Fig.8), whereas those killed by

others become rapidly dark and shrivelled (Plate V, Fig.9).

In other instances, mites may be shrunken and dark in appear­

ance but still able to crawl about.

In the present experiments, mites (adults and immature

forms) were considered as "dead" if they no longer responded to

prodding by crawling forward. Thus, mites that were too mori­

bund to crawl were considered dead even though they still

showed sorne signs of life.

As regard eggs, all dead or alive nymphs found on the

underside of leaves were considered to represent hatched or

"live" eggs. Non-hatched or "dead" eggs, were those that retain

their original shape or the shape assumed when first laid

(Plate VI, Fig.lO) and those in which the unhatched embryo re­

mained within the transparent chorion (Plate VI, Fig.ll). The

unhatched embryo has a bright reddish color and in some cases

had the forelegs and hairs apparent. Occas ionally, such embryos

(pre-motile stages) were found without the shell but were also

considered as dead eggs, due to the early stage of kill.

E. TREA TMENT

In all tests undertaken four replicates of one plant

each were used. Every record was made with the aid of a low

power stereoscopie microscope. The leaves were severed

(Plate IV, Fig.6) from the test plant for examination except

33.

in residual effect tests on adults. In this latter case, a

special support (Plate IV, Fig.?) was built in order to examine

the underside of the leaves without damaging them during the

mortality counts. The maximum, minimum and mean numbers of

adults, immature forms and eggs examined per test and per leaf

are reported in Table II.

The test plants were carried from the greenhouse to the

laboratory just prior to treatment. They were carried back to

the greenhouse as soon as the leaves had dried.

Leaves of plants were kept clean because, according to

Melvin (1948),if dirt is present on the leaves before treat­

ment, a lower mortality may resulte

1. Immediate-contact effect tests

a. Adults

Fifteen adult females of the two-spotted spider mite

were placed on each of the two primary leaves of a bean plant

from which all other leaves bad been removed. A day later, the

plants were sprayed and the mortality was recorded 48 hours

after spraying.

Effect tested

Immed• iate-

contact

34.

TABLE II

Maximum, minimum and mean numbers of adu1ts, immature forms and eggs exam-ined per test and per 1eaf.

No. No.per test1 No.per leaf2 Stage Treatment of

tests Mx Min Mean Mx Min Mean

Adult 75 120 51 104.9 21 3 13.1

Immature 75 504 145 331 85 2 41.4

Egg 74 656 166 407.3 123 9 50.9

Treated

Control

52

11

119 34 106.2 19 1 13.3

Adu1t 119 110 116.2 17 10 14.5

Total 63 107.9 - 13.5

Treated

Residual Immature Control

Total

45 1456 0 544.3 256 0 68.0

10 1857 563 1214.3 306 55 151.8

55 666.0 - - 83.3

Egg

Treated

Control

Total

45 2000 130 852.5 340

10 2024 649 1364.2 328

55 945.5

1 - 4 plants or r ep1ica tes per test.

2 - 2 1eaves per plant.

2 106.5

26 170.5

- 118.2

As can be noticed in Table II, sorne of the mites have

been lest during the course of the experimenta. These lost

mites were ignored in the recording of results and the per­

centage control has been based on the mites found on foliage

at the time of the counts. This applies in all the tests

undertaken.

b. Eggs

35.

Eggs of the two-spotted spider mite were obtained by

placing 5 females on each of the two primary leaves of a bean

plant. Forty-eight hours later these adult fernales were des­

troyed and the sprays irnmediately applied. Records of hatched

and unhatched eggs were taken 7 days later. This ?-day period

between spraying and recording of data has been found long

enough to permit almost all the untreated eggs in the check

to hatch.

c. Immatures

Cultures of immature mites were obtained by placing 5

adult females on each of the two primary leaves of a bean

plant and rernoving them 48 hours later. Five days later the

sprays were applied and the mortality count s were made 48

hours after spraying. The deposited eggs hatched normally

within the 5-day period between the removal of females and

spraying. By spraying time, the young mites had attained the

larval and protonymphal stages.

36.

2. Residual effect tests

A number of prepared bean plants ( pruned to two leaves )

were sprayed at one time. At intervals of 7, 14, 21 and 28 days

after spraying, 15 adult females were placed on each of the two

primary leaves. In adulticidal tests, mortality counts were

recorded 48 hours after the introduction of the mites while

records on eggs and immature forms were taken 8 days after the

adult mites had been introduced.

In residual effect tests, the same plant was used for

tests against the 3 stages: adult, immature and egg, while

in immediate-contact effect tests, different plants served

for each stage.

Records on eggs and immature forms in the residual

effect tests \'lere made on the deposited eggs, or immature

forms that hatched from these deposited eggs, which had been

laid by the females that had served for the adulticidal

tests.

IV. RESULTS AND DISCUSSION

For discussion in the text of this section the effect­

iveness of all materials has been graded according to the

following scale:

1. Little or no mortality (0-2~.

2. Slight kill (20-5~.

3. Moderate control (50-8o%).

4. Good kill (S0-90%).

37.

5. Excellent or complete mortality (90-lOo%).

A. EFFECT OF KELTHANE EC ON T.TELARIUS (L.)

The results (Table III) show that Kelthane EC \~S a very

effective material against the three developmental stages of

the two-spotted spider mite. This material has also been

found very efficient against all stages of a number of other

phytophagous mites (Barker and Maugham, 1956; Garmus and Unger,

1956; Jefferson and Morishita, 1956, and Jeppson et al, 1957).

Complete mortality of adults was obtained at a low con­

centration of 75 p.p.m. Even at a concentration of 25 p.p.m.

a moderate control of adults was obtained. This material

appears to be more efficient against immature forms. Complete

mortality of these forms occurred at a concentration of 25

p.p.m. Kelthane was also an excellent ovicide killing 94% of

the eggs at 50 p.p.m. These results corroborate those of

38.

TABLE III

Effect of Kelthane Ec(1) on T.telarius (L.)

Effect tested

Immed-

iate-

contact

Residual

Concen-tration

in p.p.m.

25

50

75

125

125

250

Age of spray residue be-fore infest~ ation in days

7

14

21

28

7

14

21

* 3 replicates on1y.

Corrected PTr}entage Mortality 2

Adults

62

84

lOO

lOO

lOO

95

88

Immatures

lOO

lOO

lOO

98

82*

51

55*

1

lOO

95

94

Eggs

94

94

96

21*(30)

25 (33)

37*(45)

2 (15)

40 (51)

62

56

(1) Chemical name: 1,1,bis(4-chlorophenyl}-2,2,2-trichloroethanol. Formulation: Emulsifiable concentrate containing 1.5 lb of

active ingredient per gallon. (2) The percentage mortality has been corrected by Abbott's

(1925) formula.

N.B. The percentage mortality before correction is indicated in bra ckets when the difference between it and the corrected value is 5% or more.

Barker and Maugham (1956) who found that concentrations rang­

ing from 10 to 50 p.p.m. gave a complete kill of all stages ...

when used as a spray.

The results indicate also that Kelthane EC is quite

efficient as a residual acaricide. It remains excellent

against immature forms for at least 30 days at a concentration

of 250 p.p.m. Gooa kill was attained at this concentration

against adults for over 3 weeks. The residual effectiveness

was somewhat lower against eggs, but after 30 days moderate

kill was obtained at the above mentioned concentration.

Many authors have reported that an outstanding characteristic

of this material is its very long residual life (Garmus and

Unger, 1956; Barker and Maugham, 1956).

Kelthane in an emulsifiable concentrate form was the

outstanding a caricide tested in the present study except for

the residual action on the eggs where Tedion was the best.

B:. EFFECT OF KELTHANE W ON T. TELARIUS ( L.)

The results (Table IV) indicate that the wettable powder

formulation of Kelthane in the immediate-contact tests was

39.

nearly as effective as the emulsifiable concentrate against the

developmental stages but not against the egg. This is probably

due to the fact, as claimed by Ebeling and Pence (1953), that

the solvent used in the emulsifiable concentrate formulations

40.

TABLE IV

Effect of Kelthane 18.5 w(l) on T.telarius (L.)

Concen- Age of spray Corrected Per(entage Effect tration residue be- Mortality 2) tested in fore infest-

p.p.m. at ion in da ys Adults Immatures Eggs

25 90

50 35 99 -Immed-

75 95 lOO iate-

125 90 lOO 15 contact

250 76

7 88 70 22 (31)

125 14 2 ( 7) 0 1 (12)

21 0* 2* 0* (9) Residual

7 89 76 52 (61)

250 14 71 35 42 (47)

21 11 9 9

* 3 replicates only

(1) Chemical name: l ,l,bis(4-chlorophenyl)-2,2,2-trichloroethanol. Formulation: Wettable powder containing 18.5% of active

ingredient.

(2) The percentage mortality has been corrected by Abbott's (1925) formula .

N.B. The percentage mortality before correction is indicated in brackets when the difference between it and the corrected value is 5% or more.

- - - - ----------- - - - - - - ·--·- -- -- --··

may aid the toxicant to penetrate the egg shell and to kill

the young embryo. Against the immature forms and adults at

1ower concentrations the emulsifiable concentrate form is

best. This can be explained as for the eggs. Only slight

mortality was obtained with the wettable powder form of

Kelthane at a concentration of 50 p.p.m. while a good con­

trol was reached with the emu1sifiable concentrate. The

difference in effectiveness of the two formulations against

the immature stages was not so well marked and excellent

control was obtained at a concentration of 25 p.p.m. with the

wettab1e powder form.

The residua1 effectiveness was somewhat 1ower with the

wettable powder than with the emulsifiab1e concentrate.

This statement does not agree with Ebeling and Pence (1953)

who claimed that generally the suspensions formed by the

wettable powders resu1ted in longer residua1 effectiveness.

41.

The residual action of Kelthane W declined very rapidly

after 7 days when used at 125 p~p.m. against adults and imma­

tures. The decrease was less pronounced when a higher concen­

tration was used but the control was not comparable with the

one obtained with the emulsifiable concentrate. However,

when compared with the other acaricides tested, it remained

one of the best and the results in the immediate-contact effect

tests were comparable with those obtained with Chlorobenzilate.

Furthermore, it possesses a longer residual action than

this compound.

C. EFFECT OF TEDION WON T.TELARIUS (L.)

The results (Table V) obtained with Tedion in the imme­

diate-contact effect tests show clearly that it is effective

agains~ immatures and eggs, but not adults. These results

also confirmed those obtained by many other workers {March,

1958; Meltzer, 1955; Ferguson, 1958). This compound was

more effective against immature stages than against eggs.

At a concentration of 125 p.p.m. it provided an excellent

control of the immature stages while a double concentration

was needed to control the latter. A concentration of 250

p.p.m. did not give any control of the adult stage which

proves that it is not efficient against adults.

An outstanding characteristic of this material is its

very long residual effectiveness towards eggs. After 30

days, a concentration of 250 p.p.m. gave 99% kill of the

eggs laid on dry deposits. Therefore, the establishment of

percentage mortalities against immature stages has been very

difficult because nearly all the eggs died before hatching.

No special tests were undertaken to find out if this

material causes sterility of the eggs laid by females feeding

42.

43.

TABLE V

Effect of Tedion 25 w(l) on T.telarius (L.)

Concen- Age of spray Corrected Perte~tage Effect tration residue be- Mortality 2 tested in fore infest-

p.p.m. ation in days Adults Immatures Eggs

75 67 Immed-iate- 125 14 (20) 94 3

contact 250 0 (12) 94

7 6 67 75

125 21 1 (6) 98 75

28 4 8 59

Residual

7 1 (6) 12 88

250 14 4 (10) -+ lOO

21 6 83*

+ No egg hatched.

* Percentage based on 12 immature forms on1y.

(1) Chemical name: 2,4,4' ,5-tetrachloro diphenyl sulfone. Formulation: Wettable powder containing 25% of active

ingredient.

99

(2) The percentage mortality has been corrected by Abbott's (1925} formula.

N.B. The percentage mortality before correction is indicated in brackets when the difference between it and the corrected value is 5% or more.

(8)

(65)

on dry deposits as claimed by many workers (Ferguson, 1958;

Meltzer, 1958; Huisman et al, 1955; Batth & Davidson, 1959;

Flik, 1957 and Meltzer & Dietvorst, 1957). However, the

results indicate clearly that such a process occurs. For

instance, eggs directly sprayed with Tedion at a concen­

tration of 125 p.p.m., showed only 3% kill while eggs de­

posited 28 days before on leaves previously sprayed with the

same concentration were 75% killed.

No tests were conducted on the permeation of leaves

by this compound, but according to Meltzer (1957), Huisman

et al (1955) and Meltzer (1958), Tedion has the ability to

penetrate across the leaves causing the death of young

nymphs and eggs.

D. EFFECT OF CHLOROBENZILATE W ON T.TELARIUS (L.)

. Chlorobenzilate (Table VI) is a very effective material

against the three developmental stages of the two-spotted

spider mite. The literature survey reveals that many workers

have also claimed that this compound proved to be effective

against all stages of several phytophagous mites (Armstrong,

1953; Jeppson et al, 1955). This material is, however, much

less effective than Kelthane EC specially towards eggs but

it gave excellent control of the immature and adult stages

at concentrations of 50 and 125 p.p.m., respectively. These

44.

45.

TABLE VI

Effect of Chlorobenzilate 25 w(l) on T.telarius (L.)

Concen- Age of spray Corrected Per(entage Effect tration residue be- Mortality 2) tested in fore infest-

p.p.m. ation in days Adults Immatures Eggs

25 72

50 39 97 Immed-iate- 75 86 lOO

contact 125 98 lOO 23

250 57

Residual

125

250

500

7

7

7

8

6 (11)

50

0

1

30

0 ( 9)

11 (27)

35

(1) Chemical name: Ethyl 4,4'-dichlorobenzilate. Formulation: Wettable powder containing 25% of active

ingredient.

(2) The percentage mortality has been corrected by Abbott 1 s (1925) formula.

N.B.The percentage mortality before correction is indicated in brackets when the difference between it and the corrected value is 5% or more.

concentrations in field practice are about 1/5 and i pound

in 100 gallons of water which are rouch lower than the re­

commended ones (1-1~ lbs). At 250 p.p.m., only a moderate

kill of the eggs was secured.

Armstrong (1953) obtained better results against the

developmental stages but not with the immature stages. This

may be explained by the fact that the emulsifiable concentrate

formwas used instead of the wettable powder form. Meltzer

(1955) found that 86% of the eggs died when dipped in a

solution containing 100 p.p.m. of active ingredient. The

greater kill obtained in his experiments may be only a matter

of experimental design. On the other hand, Meltzer (1955a)

found that a concentration of 100 p.p.m. is needed to obtain

a complete kill of larvae while in the present study only

75 p.p.m. was necessary. Liang and Lin (1958} in similar tests

obtained better results towards larvae. They attained 95%

kill with a concentration of' 10 p.p.m.

The residual effectiveness is rouch lo,~r than claimed

by Armstrong (1953). The results shown in Table VI, in­

dicate that a concentration of 500 p.p.m. gave only a moderate

kill of adults placed on dry deposits 7 days after spraying.

Under the same conditions, only a slight mortality of the

immature forms was obtained.

46.

E. EFFECT OF ARAMITE WON !• TELARIUS (L.)

Aramite (Table VII) is an effective material against

the motile stages of the two-spotted spider mite but not

against the egg stage. At a concentration of 125 p.p.m., a

good ki11 of adu1ts and complete ki11 of immature forms

were obtained. At a 1ower concentration about the same con­

trol was secured on both stages. Against the eggs only a

slight mortality was obtained with a much higher concen­

tration.

According to the results in Table VII, this material

has poor residua1 effectiveness. At a concentration of

500 p.p.m., only a moderate mortality of adults was ob­

tained after 7 days.

These results corroborate those obtained by Armstrong

(1950a, 1953) who claimed that Aramite has a poor ovicidal

action. His results with the motile stages were much

higher than those obtained in the present study.

47.

Effect tested

TABLE VII

Effect of Aramite 15 w{l) on T.telarius (1.)

Concen- Age of spray tration residue be-

in fore infest-p.p.m. ation in days

Corrected PerçeQtage ~lortal it y~ 2 J

Adults Immatures Eggs

48.

Immed­iate-

contact

75 125

250

73

87

69

lOO 0 (5)

26 ( 32)

Residual

125

250

500

7

7

7

20

25

73

0

1

24

0 (à)

0 ( 9)

3 (9)

(1) Chemical name: 2-(p-tert-butyl phenoxy) isopropyl 2-chlo­roethyl sulfite.

Formulation: Wettable powder containing 15% of active ingredient.

(2) The percentage mortality has been corrected by Abbott's (1925) formula.

N.B. The percentage mortality before correction is indicated in brackets when the difference between it and the corrected value is 5% or more.

F. EFFECT OF DIBROM 8 ON T.TELARIUS (L.)

Dibrom (Table VIII) is a very effective material

against the adult stage of the two-spotted spider mite. At

50 p.p.m. a nearly complete mortality was obtained in the

immediate-contact effect tests. Against the immature forms

a concentration of 250 p.p.m. provided a moderate kill while

practically no control of eggs was obtained.

These results confirmed the general statement made by

Meltzer (1955) who claimed that the phosphorous compounds

are primarily effective against adults.

This material possesses no residual effectiveness as

demonstrated in Table VIII. At 500 p.p.m., only 3, 0, and

1 percent mortalities were obtained after 9, 16 and 16 days

on adults, immature forms and eggs, respectively.

The use of this acaricide is greatly limited because

it has no residual action and practically no ovicidal effect.

According to Green and Jenkins (1958), persistance of

activity is one of the most important properties to be

looked for in a practical acaricide. In the field, it is

impossible to ensure lOO% kill immediately after spraying,

and unless a compound possesses sufficient residual activity

to control 3 generations of spider effectively, the in­

festation will probably re-establish itself.

49.

Effect tested

Immed-iate-

contact

TABLE VIII

Effect of Dibrom g(l) on T.telarius (L.)

Concen- Age of spray tration residue be-

in fore infest-p.p.m. ation in days

50

75

125

Corrected Perç~~tage Mortalityl J

Adults Immatures Eggs

99

97

lOO 64 0

50.

250 76 6 (20)

Residual

125

250

500

* 3 replicates only.

7

7

7

2*

2 (7)

3

0*

0

0

(1) Chemica1 name: 1,2 dibromo 2,2-dichloroethyl dimethy1 phosphate.

0* (9)

0 (15)

1 ( 7)

Formulation: Emulsifiable concentrate containing 8 lbs of active ingredient per gallon or 64.5% by Wt.

(2) The percentage mortality has been corrected by Abbott's (1925) formula.

N.B. The percentage mortality before correction is indicated in brackets when the difference between it a nd the corrected value is 5% or more.

G. EFFECT OF OVOTRAN WON T.TELARIUS (L.)

The results (Table IX) obtained with Ovotran showed

that it is effective against immature forms and eggs but not

against adults as most of the sulfur compounds are. Ovo­

tran is primarily effective against the very young larvae.

Laboratory tests made by Armstrong (1950) and Meltzer (1955)

confirm the above statement. However, again with this com­

pound, they obtained much higher mortalities with the con­

centrations used. This is probably just a matter of experi­

mental design.

Ovotran showed a moderate residual control of immature

stages when used at 500 p.p.m. after two weeks and an ex­

cellent kil! of eggs under the same conditions. Its residual

effectiveness dropped very rapidly when the concentration

was decreased.

This product is very slow in action. A spray con­

taining 0.4% of active ingredient against a parathion re­

sistant strain of T.telarius (L.) gave 70% mortality in 3

days and 95% in a week (Fjelddalen and Daviknes, 1952).

Although experiments have not been designed to investi­

gate leaf-permeation in the present study, it may be mention-

51.

Effect tested

TABLE IX

Effect of Ovotran 50 w(l) on !.telarius (L.)

Concen- Age of spray tration res.idue be-

in fore infest-p.p.m. ation in days

Corrected Perçentage Mortality\2)

Adults Immatures Eggs

52.

Immed­iate-

contact

75

125

250

12 (19)

0 (11)

27

83 1 (6)

59

Residual

125

250

500

7

7

7

3

2 (7)

0

5

0

76

0 (12)

15 (30}

93

(1} Chemica1 name: p-chlorophenyl p-chlorobenzene sulfonate. Formulation: Wettable powder containing 50% of active

ingredient.

(2) The percentage mortality has been corrected by Abbott's (1925) fonnula.

N.B. The percentage mortality before correction is indicated in brackets when the difference between it and the corrected value is 5% or more.

ed that many workers found that a local systemic action

was present when this acaricide was used. Eggs and nymphs

were killed completely on the underside of leaves when the

opposite surface was treated (Blauvelt & Hathaway, 1950;

Armstrong et al, 1954,and Meltzer, 1957).

Unlike Tedion, Ovotran does not cause sterility of the

eggs laid by fernales feeding on dry deposits. Armstrong

(1950} claimed that eggs laid in these conditions were viable

but failed to hatch due mainly to its extraordinary ovicidal

action.

H. IMMEDIATE-CONTACT EFFECTS OF DIMITE E AND

MALATHION EON T.TELARIUS (L.}

Dimite and Malathion (Table X} are primarily effective

against the motile stages of the two-spotted spider mite.

Against eggs, however, Dimite gave a much better control

53.

than Malathion. At 250 p.p.m. a slight mortality of the eggs

was obtained with Dimite while none was secured with Malathion.

Also, against adults and immature forms, Dimite provided a

higher kill than Malathion. An excellent mortality of the

immature forms was obtained at 250 p.p.m., while only a moder­

ate kill was ensured with Malathion against the same stage.

Against adults, a good control was obtained with Dimite at

250 p.p.m., while only a slight one was secured with

Mala thion.

Materia1

TABLE X

Immediate-contact affects of Dimite 25 E(1 )

and Malathion 57 E( 2) on T.te1arius (L.)

Concen­tration in p.p.m.

Corrected PerçeQtage Morta1ityl3 J

Adults Immatures Eggs

54.

125 65 (71) 53 4 (9}

Dimite 25 E

250 85 92 43 (52)

125 40 (50) 9

Ma1athion 57 E

250 47 (53) 57

(1) Chemical name: 2,2-bis (p-chlorophenyl) ethanol, Formulation: Emu1sifiable concentrate containing

25% of active ingredient.

(2) Chemica1 name: O,O-dimethy1 dithiophosphate of diethy1 mercapto succinate.

Formulation: Emu1sifiable concentrate containing 57% of active ingredient,

(3) The percentage mortality has been corrected by Abbott's (1925) formula,

0 (5)

0 (14)

N.B. The percentage morta1ity before correction is indicated in brackets when the difference between it and the cor­rected value is 5% or more.

The residual toxicity of these compounds was not in­

vestigated in the present study, but according to Armstrong

(1950) and Ross & Armstrong (1949), Dimite showed a residua1

action for at 1east 14 days.

Meltzer (1955a) reported that Dimite provided a complete

mortality of the larvae when used at a concentration of 25

p.p.m. In the pres.ent study, an excellent kill was obtained

but at a concentration 10 times higher.

I. ~ŒDIATE-CONTACT EFFECTS OF TRITHION W, ETHION W

AND MALATHION WON T.TELARIUS (L.)

Among these three organic phosphorous compounds (Table

XI) only Malathion seemed to confirm Meltzer's statement

about these types of material, which is that phosphorous

acaricides are primarily effective against adults of the

two-spotted spider mite. Malathion is not comparable with

the best acaricides tested in the present study. This may be

explained by the fact that the highest concentration used

was only one-third of the strength recommended for field

use. Even with such a low concentration (250 p.p.m.}, a

moderate control was obtained.

Trithion and Ethion gave surprisingly good control of

the eggs. With Ethion used at 250 p.p.m., the control on eggs

was as good as that of adults and of immature forms. This

55.

TABLE XI

Immediate-contact effects of Trithion 25 w(l)

Ethion 25 w( 2 ) and Malathion 25 w(3) on

T.te1arius ( L.)

Concen- Corrected Peryeytage tration Mortality 4 Mate rial in p.p.m. Adu1ts Immatures Eggs

125 7 (14) 55 5 Trithion 25 W

250 64 80 58

125 20 (26) 16 12 Ethion 25 W

250 54 (59) 49 50

125 28 03) 8 Malathion 25 W

(1)

250 62 (67) 26

Chemical name: 0,0,-diethyl 3-(p~chlorophenyl thio­metnyl) phosphorothioate.

Formulation: Wettable powder containing 25% of active ingredient.

0

3

(2) Chemical name: o,o,or.,ot-tetraethyl S,sr-methylene bis phosphorothioate.

Formulation: Wettable powder containing 25% of active ingredient.

(3) Chemical name: o,O-dimethyl dithiophosphate of diethyl mercapto succinate.

Formulation: Wettable powder containing 25% of active ingredient.

(4) The percentage mortality has been corrected by Abbott's (1925) formula.

(11)

N.B. The percentage mortality before correction is indicated in brackets when the difference between it and the corrected value is 5% or more.

56.

concentration, which is the recommended one, provided only

a moderate control of the three developmental stages. On

the other hand, Trithion gave a better control of im­

mature forms than of the other 2 stages, but it was still

insufficient for practical purposes. Liang and Lin (1958)

using another method of testing, obtained much better

control with Trithion than in the present study. In their

tests, 95% mortality of larvae was obtained at a concen­

tration of only 6-7 p.p.m.

These three compounds do not compare favorably with

such acaricides as Kelthane and Tedion.

J. IMMEDIATE-CONTACT EFFECTS OF MITOX \'tf, THIODAN W

AND KARATHANE WON T.TELARIUS (L.)

Table XII shows results obtained with three different

kinds of acaricides, a sulfur, a chlorinated and a dinitro

compound. No test on the two-spotted spider mite with

Thiodan has been found in the literature. According to

the results obtained in the present trials, it is not pro­

mising against any of the stages of T.telarius (L.).

Mitox was not tested thoroughly in the present work,

but it seems to possess great activity as claimed by many

57.

TABLE XII

Immediate-contact effects of Mitox 40 w(l),

Thiodan 25 w(2) and Karathane 25 w(3)

on T.telarius (L.)

Concen- Corrected Perfeytage Material tration Mortality 4

58.

in p.p.m. Adults: Immatures Eggs

125 19 (25) 51 Mitox 40 W

250 0 (11) 48

125 2.3 (28} 4 Thiodan 25 W

250 38 (45) 16

75 81

Karathane 25 W 125 12 (18) 82

250 lOO

(1} Chemical name: p-chlorobenzyl p-chlorophenyl sulfide. Formulation: Wettable pm"lder containing 40% of active

ingredient.

1

94

0

2

2

98

{2) Chemical name: Hexachlorohexahydro-6, 9-methanobenzodio­xathiepin-3-oxide.

Formulation: Wettable powder containing 25% of active ingredient.

(3} Chemical name: (1-methylheptyl}dinitrophenyl crotonate (1-methylheptyl)dinitrophenol phenol and related compounds.

Formulation: Wettable powder containing 25% of active ingredient.

(4) The percentage mortality has been corrected by Abbott's (1925) formula .

N.B. The percentage mortality before correction is indicated in brackets when the difference between it and the corrected value is 5% or more.

(10)

(6)

workers (Cranham et al, 1953; Cranham & Stevenson, 1955 and

Meltzer, 1955), against mite eggs and larvae but not adults.

The results (Table XII) obtained with this material, corrobo­

rate those of Meltzer (1955) who found that at 300 p.p.m.

lOO% of dipped eggs were killed. An excellent kill of the

eggs was secured in the present study at a lower concen­

tration.

No tests were carried out on the residual effective­

ness and leaf-permeation of Mitox, but a survey of liter­

ature showed that it possesses a persistent ovicidal effect

and acts as a stomach poison on the nymphs (Cranham et al,

1953 and Armstrong et al, 1954). Also, this material showed

the ability to penetrate across and diffuse through leaves

as do certain of the substituted benzene sulfonates, such

as Tedion and Ovotran (Cranham et al, 1953; Armstrong et al,

1954, and Meltzer, 1957).

Karathane, a dinitro compound, is primarily a fungicide

but it gave surprisingly effective control of the 3 develop­

mental stages of this mite. At the recommended dose, which

is approximately 250 p.p.m., complete control of the adults

was obtained and nearly all the eggs were destroyed. At half

this strength, it provided a good control. It should be

mentioned that the effectiveness of this material for adults

and eggs, decreased very rapidly when the concentration

was lowered (Table XII).

59.

The results obtained with Karathane in the present

trials seem much better than those obtained by Meltzer (1955).

He found that complete mortality of nymphs and adults was

secured at a concentration of 1000 p.p.m. while in our tests,

complete mortality of adults was obtained at 250 p.p.m. and

82% of the nymphs at half this dose.

McClellan & Smith (1951) and Rich (1954) reported that

this material is very effective against all stages of develop­

ment of T.telari.us (L.) but lacks residual toxicity at the

concentration used for contact action. Armstrong (1950a)

and Meltzer (1955) found that when used at 1000 p.p.m., it

bas a residual action of about 5 days.

Armstrong (1953) reported that this material acts very

slowly as does Ovotran. In his tests, 1 pound in 100 gal.

of water destroyed 57.6% of active two-spotted spider mite

in 3 days whi1e 86.3% were destroyed in 7 days.

K. EFFECTS OF SYSTEMIC COMPOUNDS ON T.TELARIUS (L.)

The compounds here designated as systemic are those re­

cognized as such in the literature or technica1 data sheets

supplied by the different companies. Al1 these compounds be­

long to the organic phosphorous group. The systemic effect

was not sougbt in the present study but these materials were

tested with the purpose of comparison with the other compounds

6o.

under investigation to find their contact and residual

actions when applied as sprays. The results obtained with

these compounds are shown in Tables XIII, XIV, XV and XVI.

61.

All the compounds except Ekatin M gave excellent im­

med_iate-contact kill towards adults of the two-spotted spider

mite at a re1atively low concentration. They compare very

well with the best non-systemic acaricides tested against

adu1ts in this project. Among these compounds, we may men­

tion Ke1thane, Chlorobenzi1ate and Dibrom.

In immediate-contact tests against eggs, on1y Exp. Ins.

l$706 gave a good control at the low concentration of 125

p.p.m. Exp.Ins. 12$80, Systox and Di-syston seem promising

because they gave a moderate control at such a 1ow concen­

tration. The resu1ts obtained in the tests with immature

forms are rather low at the concentration tested but these

compounds would probably have given better results if they

had been tested at higher concentrations. Among all these

on1y Dimecron was tested at 250 p.p.m. and gave 99% ki11 of

immature forms, which permits us to conclude that these

materials are promising against the young stages.

These compounds, besides possessing a systemic effect,

have very good contact and probab1y fumigant effect (Davis &

Sessions, 1953). However, Herne (1959) reported that Ekatin

M did not compare favourab1y with a number of other acaricides

62.

TABLE XIII

Effects of Exp. Ins. 18706(1 ) and Exp. Ins. 12880( 2)

on T.telarius ( L.)

Age of Material Effect Concen- spray re- Corrected Per~entage

tested tration s.idue be- Mortality 3) in fore in-

p.p.m. festation in days Adults Immatures Eggs

Irnme-dia te- 125 97 48 85 contact

Exp. Ins. 18706 7 34 4 2 (22)

Re si- 125 14 25 -

dual

250 7 38 14 0 (13)

Imme-dia te- 125 85 . 54 57 contact

Exp. Ins. 12880 7 43 13 9 ( 27)

Re si- 125 14 32

dual

250 7 35 10

(1) Chemical name: O,O-dimethyl S-(N-ethyl carbamoyl-methyl) phosphorodithioate.

Formulation: Soluble concentrate containing 25% of active ingredient.

( 2 ) Chemi cal name: 0, 0-dimethyl s- ( N-methyl cc3.rbamoyl-methyl) phosphorodithioate.

Formulation: Soluble concentrate containing 46% of active ingredi ent.

(3) The percentage mor t a l i ty has been correct ed by Abbott's (1925) formula.

0

N.B. The percentage morta lity before correction is indicated in brackets when the di fference between it and the corrected value is 5% or more .

(7)

63.

TABLE XIV

Effects of Disyston 25 E(l) and Systox 25 E( 2 )

on T.telarius ( L.)

Concen- Age of Mate rial Effect tration spray re- Corrected Per{e)tage

tested in sidue be- Mortality 3 p.p.m. fore in-

festation in days Adults Immatures Eggs

Imme-dia te- 125 96 59 58 contact

Disyston (26) (23) 25 E 7 20 3 4

125 Re si- 14 6 dual

250 7 9 1 0 ( 13)

Imme-dia te- 125 97 64 61 contact

Systox 25 E 7 32 8 0 (18)

125 Re si- 14 9 dual

250 7 22 4 (19)

(1) Chemical name: o,O-diethyl S-2{ethylthio) ethyl phos­phorothioate.

Formulation: Emulsifiable concentrate containing 25% of active ingredient.

(2) Chemical name: O,O-diethyl 0 (and S)-2-(e.thylthio) ethyl phosphorothioate.

Formulation: Emulsifiable concentrate containing 25% of active ingredient.

(3) The percentage mortality has been corrected by Abbott's (1925) formula.

N.B. The percentage mortality before correction is indicated in brackets wgen the difference between it and the corrected value is 5% or more.

TABLE XV

Effects of Ekatin M(l) and Phosphamidon 4(2)

on T.telarius (L.)

Concen­Material Effect tration

tested in

Age of spray re­sidue be­fore in­festation in days

Corrected Percentage Morta1ity(3)

p.p.m.

Adults Immatures Eggs

Ekatin M

Phospha­midon 4

Imme­diate­contact

Resi­dua1

Imme­diate­contact

Re si­dual

125

125

250

125

125

250

7

14

7

7

14

7

61

0 (5)

4

1

97

13 ( 19)

2

10

0

0

75

1

0

(1) Chemical name: O,O-dimethy1-S(morpho1ino-carbaminyl­methyl) dithiophosphate.

5 (12)

0 (19)

0 (9)

17 (24)

24 (40)

6 (21)

Formulation: Emulsifiable concentrate containing approxi­mately lOO% of active ingredient.

(2) Chemical name: l-ch1oro-1-diethylcarbamoyl-l-propen-2-yl dimethyl phosphate.

Formulation: Emulsifiable concentrate containing 4 lbs of active ingredient per gallon.

(3) The percentage mortality has been corrected by Abbott's (1925) formula.

N.B. The percentage mortality before correction is indicated in brackets when the difference between it and the corrected value is 5% or more.

Effect teeted

TABLE XVI

Effect of Dirnecron lOO(l) on T.telarius (L.)

Concen­tration

in

Corrected PerçeQtage Mortality\2}

65.

p.p.m.

Age of spray residue be­fore infest­ation in days Adu1ts Immatures Eggs

Immediate-contact 125 94 74 8 (15}

250 lOO 99 19

7 13 (19) 0 1 (21)

Residua1 125 14 2

250 7 11 0 4 (19)

(1) Chemical name: 2-chloro-2-diethy1ecarbamoyl-l-methyl­viny1-dimethyl phosphate.

Formulation: Emuls i fiable concentrate containing lOO% of active ingredient.

(2) The percentage mortality has been corrected by Abbott's {1925) formula.

N.B. The percentage morta1ity before correction is indica ted in bra ckets when the difference between it and the corrected value is 5% or more.

already available, either in its systemic or contact activity.

These studies corroborate also the statement made by

Meltzer (1955) who claimed that the phosphorous compounds

are primarily effective against adults.

Residual effectiveness tests were also carried out

with these systemic compounds. They gave surprisingly poor

results because many workers claimed that a great character­

istic of the systemic compounds is their long residual action.

The only explanation would seem to be that they were tested

at too lo\.'1 concentrations.

None of the materials gave results worthy of mention

in these residual action tests. For instance, Exp. Ins.

18706, the best one, at a concentration of 250 p.p.m. gave

only 38% kill after 9 days against adults.

L. IMMEDIATE-CONTACT EFFECTS OF SELECTED ORGANIC MOLECULES

ON T.TELARIUS (1.)

The results obtained with these different organic mole­

cules are reported in Ta ble XVII. None of these compounds

showed any results comparable with present acaricides avail­

able except p~chlorobenzyl 2-chloroethyl sulfide (No. 4)

that showed promise against eggs and bis (p-chlorophenyl

merca pto) propane (No.l8) that gave promis ing result s against

66.

Formu­lation used

No 1

E.C. lü%

No 2 10% (Ace-tone)

No 3

E.c. 25%

No 4 E.C. 25%

TABLE XVII

Immediate-contact effects of selected organic molecules(l)on T.telarius CL.)

Chemical name and formula

4,4 1 -Dichlorobenzene sulfonanilide

ClQ S02-NH <=> Cl

p-chlorobenzyl 3 amino-2 hydroxy-propyl sulfide

Cl~CH2SCH2CHOHCH2HH2

0-Chlorobenzyl 2-chloroethyl sulfide

~CH2SCH2CH2Cl Cl

p-chlorobenzyl 2-chloroethyl sulfide

Cl<=:)CH2SCH2CH2Cl

Concen­tration

in p.p.m.

250

250

250

250

Corrected Perçentage Mortality\2)

Adults Immatures Eggs

0 (13) 3 (9) 0

6 (13) 1 (6) 0

(9)

5 (13) 1 (6) 10 (14)

9 (17) 0 39 (J'\ ---.J .

Forrr1U-lat ion used

No 5

E.C. 15%

No 6

E.C. 251;

No 7 E.C. 25% -No 8

E.c. 25%

TABLE XVII {cont 1 d)

Immediate-contact effects of selected organic molecules(l) on T.telarius (L.)

Concen- Corrected Perye)tage tration Mortality 2

Chemical name and formula in p.p.m. Adults Immatures Eggs

p-chlorobenzyl 2-aminoethyl sulfide

Cl~ CHzSCHzCHzNH 2 250 7 (15) 0 5 ( 10)

p-chlorophenyl 4-chlorobutyl sulfide

Cl<=> SCHzCHzCH2CHzCl 250 7 { 15) 0 ( 5 ) 2 (8)

n-dodecyl 2-ch1oroethy1 su1fide CH 3 (GHz) lüCH2SCH2CH2Cl 250 11 (19) 0 6 (11)

2-thiocyanatoethyl-p-chlorobenzyl sulfide

Clc=>CH2SCHzCHzSCN 250 6 (15) 17 15 ( 20)

(J'\ CQ. •

Formu­Lation used

No 9 lü% {Ace-tone)

No 10

E.C. 3.6%

No ll E.C. 10%

TABLE XVII (cont 1 d)

Immediate-contact effects of selected organic molecules(l) on T.telarius (L.)

'Chemical name and formula

1,4-bis(cyanomethyl) benzene

CNCH 2CJcH2CN

2,2 1 -thiodiethyl acetoacetic ether

CH 3 COyH COOC2H 5 s ' CH 3 COCHCOOC2H 5

Hexadecyl N,N-dimethyldithiocarbamate CH3(CH2)14CH2SCN(CH3)2

" s

Concen­tration

in p.p.m.

250

250

250

Corrected Perçentage Mortality~ 2)

Adults Immatures

2 (9) 0

12 ( 24) 6 (11)

3 (11) 1 ( 6)

Eggs

2 (7)

0 (9)

0 (7)

()'. 'Û •

Formu-lat ion used

No 12 E.C. 8.3%

No 13

E.c. 25%

No 14

E.C. 8.3%

No 15

E.c. 15%

.TABLE XVII (cont'd)

Immediate-contact effects of se1ected organic molecules(l) on ,!.te1arius (L.)

Concen- Corrected PerTe~tage tration Mortality 2

Chemica1 name and formula in p.p.m. Adults Inunatures Eggs

1,2-bis(p-chlorophenyl-mercapto) ethane 250 1 (14) 5 ( 10) 1 (9) C1<====>SCH2CH2S~Cl

~-ch1orobenzll mercapto-ethy1 -ch1oroethy ether

Cl<====>CH2SCH2CH20CH2CH2Cl 250 6 (14) 9 7 ( 12)

Bis (p-chlorobenzyl mercapto) methane

Cl<====>CH2SCH2SCH2<==:>c1 250 8 (20) 11 (16) 2 ( 10)

Bis (p-chloropheny1 mercapto) penthane

(C1~SCH2CH2)2CH2 250 3 ( 10) 15 (20) 2

-....)

0 •

TABLE XVII (cont 1 d)

Immediate-contact effects of selected organic molecules(l) on T.telarius (L.)

Formu-lat ion Chemical name and formula used

No 16 Bis(p-chlorophenyl mercapto) butane

E.c. 10% (c1QSCH2CH2)2

No 17 Bis(p-chlorobenzyl mercapto) butane

E.c. (Cl~CH2SCH2CH2)2 20%

No 18 Bis(p-chlorophenyl mercapto) propane

E.C. Cl C=> SCH2CH2CH2S C=> Cl 10%

(1) Courtesy of the Dominion Rubber Company.

Concen­tration

in p.p.m.

250

250

250

Corrected Perçe~tage Mortality\2}

Adults Immatures

2 (9) 3 (8)

•

9 (16) 5 ( 10)

4 (17) 50

(2} The percentage mortality has been corrected by Abbott•s (1925) formula.

Eggs

0 ( 8)

2 (10)

38 (43)

N.B.The percentage mortality before correction is indicated in brackets when the difference between it and the corrected value is 5% or more.

-..J l-' •

immature stages and eggs. Many of these organic molecules

were tested for their insecticidal potency by Musgrave and

Kukovica (1953, 1955 and 1956) on two kinds of aphids, M.

pisi (Kaltenbach) and A.fabae (Scop.). Of those reported

by these authors and tested in the present study, only a

few were considered as insecticidal and among these bis

(p-chlorophenyl mercapto) propane was included.

M. OBSERVATIONS

1. Chlorinated compounds

In general, adults of the two-spotted spider mite

killed by the chlorinated compounds, such as Dimite,

Kelthane and Chlorobenzilate, retained a remarkably life-

72.

like appearance and posture (Plate v, Fig. 8) even several

days after treatment. The body kept the same shape and turgid

condition as it had before death. Also, the color was al­

most exactly the same though a little less shiny. The legs

were stretched out perfectly but in a more rigid position.

The forelegs and mouthparts were slightly more lifted up

than in the case of a living adult.

Close to these life-like appearance mites, no eggs or

at least a few were found while near living mites a large

qua~ty was deposited. This observation was used in cases

of doubt whether it was a living or a dead mite.

Among all chlorinated compounds tested, only one ex­

ception occurred, Thiodan. Adults killed by this material

were shrivelled and dried up as with the organic phosphorous

and sulfur compounds. The following explanation may be ad­

vanced: This technical chemical contains two insecticidally

active geometrie isomers of which one contains sulfur. The

sulfurous atom caused probably the shrivelling and drying up

of the mites.

Eggs of the two~spotted spider mite killed by the chlor­

inated compounds retained the same shape and appearance as

newly laid eggs (Plate VI, Fig.lO). Any differences between

the two types of eggs (newly laid and killed by these com­

pounds) are very difficult to find. The potential embryo was

probably killed immediately when the material came in contact

with the eggs, thus inhibiting all growth immediately.

The immature two-spotted spider mites killed by the

chlorinated compounds bad exactly the same characteristics

as described above under adults. They were minute, nearly

all larvae and retained a life-like appearance. Thiodan

was again an exception in this case. The immature forms be­

came shrivelled and dried up. In ovicidal tests, most larvae

that hatched from sprayed eggs, were killed immediately by

these materials and possessed the same characteristics just

described.

73.

74.

2. Organic phosphorous and sulfur compounds

Adults and immature stages of the two-spotted spider mite

killed by organic phosphorous compounds such as Trithion,

Dibrom, Ethion, etc., and organic sulfur compounds such as

Mitox, Ovotran, Aramite, Tedion, etc., were completely shrivel­

led and dried up and their legs were bent under their body

(Plate V, Fig. 9). Furthermore, their color which in life is

shiny green with dark spots became reddish brown. The differ­

ence between living and dead mites was unmistakable.

Eggs killed by these organic sulfur and phosphorous

compounds are characteristic also. They lose their normal

shape completely. The unhatched bright reddish embryo re­

mains within the transparent chorion (Plate VI, Fig.ll).

Sometimes forelegs and hairs were apparent.

In contrast to the results with the chlorinated com­

pounds, these compounds did not inhibit growth of the

potential embryo immediately when the poison touched the eggs.

With phosphorous compounds, the ovicidal action may be ex­

plained as follows: Vapor gains entry to the egg probably in

the exchange of gases in the respiratory process. After

gaining entry, the material is retained, later acting on

cholinesterase. This inhibition is of no physiological

importance in the absence of acetyl choline. Initially,

acetyl choline is present at low levels, but as nervous

-· ··- --- - - - --

75.

activity continues and without the normal controlling mechanism,

acetyl choline accumulates to toxic levels and death ensues

(Smith & Wagenknecht, 1959).

These observations on eggs do not hold for Tedion, a

sulfur compound. Eggs killed by this material possessed the

same characteristics as those described under the chlorinated

compounds, that is they retained their normal shape. This may

be explained by the fact that females feeding on dry deposits

of this acaricide laid unviable eggs. However, it does not

provide any explanations for the viable eggs that were sprayed

directly and which retained also their original shape. On

the other hand, they had a light reddish color.

In ovicidal tests, with sulfur compounds, most young

larvae were killed immediately as soon as they hatched out

from sprayed eggs. These killed immature forms possessed the

same characteristics as described earlier for immature stages.

The above observations hold also for all the systemic

materials tested. These compounds were all phosphorous mat­

erials and were quite characteristic of this group. In ad­

ulticidal tests with these sytemic acaricides, a large number

of adults were not found on the leaves at the time the

mortality records were taken. Most of them were captured

in the petroleum jelly barrier deposited on the stem of the

test plants. Do systemic compounds cause a greater number

of mites to leave the plants than other compounds? No tests

were made on this, but according to these observations it

seems true.

The observations on immature stages and adults affect­

ed by the selected organic molecules are the same as those

for the organic phosphorous and sulfur compounds. All these

compounds but one have at least one sulfur atom in the chain

and, therefore, possess the same characteristics as those

described above for the organic sulfur compounds.

3. Dinitro compounds

76.

Most adults killed by Karathane, the only dinitro com­

pound tested, retained the same characteristics as those

described under chlorinated compounds. The coloration,

however, was different. Both spots on the dorsum became rouch

darker and dull in appearance while the rest of the body turned

a reddish brown instead of remaining green as with the chlorin­

ated compounds.

The immature stages killed by this compound became

shrivelled and completely dried up as with the organic phos­

phorous and sulfur compounds.

Mos t but not all of the eggs retained their origina l

shape, but became yellowish-green. Sorne dried up, but the

potential embryo was not visible through the chorion. One may

conclude that the embryo in these cases were killed in­

stantly with the contact of the poison as was the case

with the chlorinated compounds.

77.

V. SUMMARY AND CONCLUSIONS

Kelthane was the most generally effective chemical of

20 different commercial acaricides and 18 selected organic

molecules tested. At 25 parts per million the material gave

lOO per cent immediate kill of nymphs while at 75 parts per

million, it killed all stages. At 125 parts per million,

it was 80 percent effective against living forms after seven

days but most eggs survived. However, females on treated

surfaces died rapidly without appreciable oviposition. The

emulsifiable concentrate formulation was generally slightly

superior to the wettable powder.

Chlorobenzilate and Karathane were also effective

against adults, immature forms and eggs at relatively low

dosages. The eggs in general were the most resistant forms.

Tedion, Ovotran and Mitox were effective against eggs

and immature forms but not against adults. Tedion had the

78.

best residual effectiveness of all materials versus eggs. It

also affected adults in such a way that they laid unviable eggs.

The phosphorous compounds were primarily effective

against adults (Cf Meltzer, 1955) although the systemic phos­

phorous compounds showed promise against immature forms.

Only p-chlorobenzyl 2-chloroethyl sulfide, which showed

promise against eggs and bis (p-chlorophenyl mercapto) pro­

pane, which showed promise against eggs and immature forms,

were worth of mention among the selected organic molecules

tested.

The action of chlorinated compounds was characterized

by the fact that its victims, regardless of stage retained

a life-like form. The development of eggs appeared to be

arrested almost at once. No developing embryos were visible

through the chorion.

On the other hand, the organic phosphorous compounds

and organic molecules which contained sulfur resulted in

dead adults and immature forms with a contracted, shrivelled,

"desiccated" appearance and in the death of developing embryos

at a later stage so that they appeared as distinct embryos

through the chorion or even emerged before dying. A study of

the physiological bases of these differences might well

prove profitable.

The technique developed involving a single uniform

79.

host plant, a single species of test animal, a spraying

technique and method of expressing dosage which is at least

partially comparable to field methods, and a design which allows

for the accumulation of data on all the important effects of

the materials within a short period of time proved very

practical and informative.

VI. ACKNCMLEDGE~1ENTS

The author gratefully acknowledges the encouragement

and assistance of Dr. F.O. Morrison, his director of

research, in the planning and conduct of the experimental

work and in the preparation of this manuscript. Dr.Morrison

also prepared all the photographs appearing in the text.

The author also wishes to express his appreciation to

the authorities of the Provincial Department of Agriculture

for granting leave-of-absence to pursue graduate studies

and for the grants awarded by the Provincial Agricultural

Research Council.

Sincere thanks are also expressed to all the chernical

companies who donated the materials used in this research,

and to Mr. Walter M. Stewart for scholarships awarded during

this period of study.

80.

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81.

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1958. Efficacit~ compar~s de quelques produits acaricides. Phytiatrie-phytophar., 7 (4): 127-132.

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Cranham, J.E. and H.A. Stevenson.

1955. p-chlorobenzy1 p-chlorophenyl su1phide - Further aspects of field use. • Chem. & Ind. (London) p. 383.

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1953. On the systemic action of systox on cotton. J. econ. Ent., 46: 526-527.

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1944. Technique for studying the residual value of organic insecticides. J. econ. Ent., 37: 311-312.

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1953. Pesticides formulation- Influence of formulation on effectiveness. J. Agr. Fd Chem., 1 (5): 386-398.

1954. Susceptibility of acaricides of two-spotted spider mites (T.telarius) in the egg, larval and adult stages. J. econ. Ent., 47 (5}: 789-795.

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1958. Tedion, an outstanding new acaricide. J. econ. Ent., 51 (3): 352-354.

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1960. Entoma, 13th Edition 1959-60, Pub.Ent.Soc.Amer.

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1952. Veksthusspinnmidder resistente mot thiofosfor­midler funnet i Norge. (Greenhouse spider-mites resistant to parathion found in Norway). Gartneryrket No. 13 repr. 8 pp.

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1957. Results with Tedion V.l8. Rpt. XIVth Int.Hort.Cong., 1955, pp. 837-844.

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1952. Spider mite control on cotton. J. econ. Ent., 45: 523-526.

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1956. A new miticide ••• Kelthane Agr. Chem., 11 (7): 41-43.

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1958. The mite ovicida1 activities of sorne chloro­substituted bisphenoxymethanes and related compounds. J.Sci. Fd Agric., 9 (9): 536-539.

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1954. Chemical structure of a series of organic sulfites and its toxicity to the two-spotted spider mite ( T. telarius). J7Agr. Fd Chem., 2: 140-142.

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1959. Summary of greenhouse trials of Ekatin-M against the two-spotted spider mite on Scarlet Runner Bean. Insecticide Newsletter, Sei. Inf. Sec., Res. Branch, Canada Dept. Agr., Vol. 8 (4): 10.

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1953. Laboratory tests of acaricides on eggs of European red mite. J. econ. Ent., 46: 112-115.

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1955. A new acaricide, 2,4,5,4'-Tetrach1orodiphenylsulfone. Nature, 176: 515-516.

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1955. Screening tests with insecticides for control of red-spider mite (Tetranychus urticae Koch) on beans. N.Z. J. Sei. Tech (A) 36 PP• 454-459.

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1956. Rohm and Haas ~-293 for mite control on ornamentals. J. econ. Ent., 49: 392-393.

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1955. Control of mites on citrus with chlorobenzilate. J. econ. Ent., 48: 375-377.

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1951. Laboratory experiments on the toxicity of potential acaricides. Ann. Rept East Malling Res. Sta., 1950, pp. 164-171.

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1954. The toxicity of phenyl benzenesulphonate and sorne chlorinated derivatives towards eggs of certain tetranychid mites. J. Sei. Fd Agric., 5 (7): 323-330.

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1951. The ovicidal a ctivity of sorne phenyltrichloro­methyl carbinols and their esters towards eggs of the gl asshouse red sp ider mite (T.telarius L.). J. Sei. Fd Agric., 2: 204-207.

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90.

PLÀTES I - VI

PLATE I

Fig. l Beans sown thickly in flats of river sand and ready for transplantation.

Fig. 2 Set-up of bean plants after spraying in the greenhouse.

PLATE II

Fig. 3 Bean plant in 4-inch pot trimmed to two leaves. White petroleum jelly was smeared around the stem to keep stray mites off plants and test mites on plants.

Fig. 4 Nippine off of the central shoot of bean plants.

PLATE III

Fig. 5 Spraying room containing the turntable, a hood, a fan Rnd the spray equipment.

PLATE IV

Fig. 6 Recording of mortality on a severed leaf under a stereoscopie microscope.

Fig. 7 Special support to examine the underside of leaves without cutting nor damaging them.

PLATE V

Fig. 8 Adult of T.telarius (L.) killed by chlorinated compounds- Life-like appearance and posture.

Fig. 9 Adult of T.telarius (L.) kill ed by phosphorous and sulfur compounds Shrivelled and com-pletely dried up.

PLATE VI

Fig. 10

Fig. 11

Eggs of T.te1arius (L.) ki1led by chlorinated compounds Same shape and appearance as when first laid.

Eggs of T.telarius (L.) killed by phosphorous and sulfür compounds - Unhatched embryo show­ing through the transparent chorion.