REVIEW OF LITERATURE

Page. .7

2. REVIEW OF LITERATURE.

IGRS evolved rapidly following the discovery of juvenile h o m n e

and its activity in Cecropia moth by Williams (1956). ?he significant

role of JH and JH mimics in interrupting the normal dwelopnent of

insects (Wigglesworth, 1936, 1970) stimulated scientists to consider

these canpounds as potential insect control agents (Slama, etc., 1974: Hendrick g. , 1973: Rmanuk, 1981: Sobotka and Zabza, 1981). Subsequently, another qroup of IGRs emerged in 1970 when insecticidal

properties of benzoylchenylurea (BPU) canpounds were demonstrated by

Philips-[Xlphar company. Advantageous characteristics of IGRs led to

the steady synthesis of several canpounds which were broadly

classified into two qroups n m l y Juvenile Hormone Analogs (JHAs) or

Juvenoids and Chitin synthesis inhibitors (CSI). ?bough many IGRs

exhibited varying degrees of insecticidal activity and specificity,

only methoprene and diflubenzuron showed great promise in controlling

agricultural pests and disease vectors.

Numerous information regarding IGRs started accumulating as a

result of intensive research in this field. Recent works on IGRs w e r

the last two decades are mainly concerned with Ias' mode action at

biochemical and organisma1 level and their ccntrol potency in

suppressing pest ppulat ion.

Page.. B

2.1. Mode of action and biochemical effects:

The ef fec ts of IGRs a t the biochemical level a r e the fundanental

t o understand the rode of action of the chemical. Biochemical ef fec ts

of juvenoids a r e complex and vary from one analog t o another since

they function a s juvenile hormone agonists or antagonists or both

(Kramer and Staa l , 1981). JHA has two dis t inc t biochemical effects.

In larvae i t retards developnent and in adults a f fec ts vitellogenesis

during ovarian developoent (Coudron & &., 1981). Regulation,

transportation and feed back control of the juvenile hormone t i t r e

were seemed t o be altered by the JHAs in many pest insects (Schia lek

e t &. , 1973: Tobe and Stay, 1979: De Kort and Granger, 1981). The - juvenoid methoprene inhibited somatic growth (Krypsin-Sorensen 6

al . , 1979), reduced the metabolic r a t e (Slama and Hotkova, 1975), - depleted glycogen and l ip id reserves (Downer 5 &., 1976) in various

agricultural pests. Juvenoids were a l so found t o inhibit t he

synthesis of nucleic acids e i ther RNA (Miller and Collins, 1975) or

DNA ( V i jverberg and Giasel, 1976: Scheller d., 1978) o r both

(Himeno & g., 1979). The ef fec ts of JHA on regulation and

inhibition of protein synthesis have been demonstrated in the

hanogenates and the imaginal d isc of Drosophila melanogastor (Breccia

e t a l . , 1976; Fristrom &. , 1976). --

A particularly important protein is vitelloqenin which is

essential t o insect egg maturation. Methoprene is effective in

converting t h e f a t 'body of adult female Locusta migratoria £ran a

nu t r ien t s t o r e depot t o a s i t e of vi tel logenin synthesis and

Secretion (Couble et &., 1979; Chen and Wyatt 1981). Nethoprene

ac t iva tes t h e f a t bodies in isolated abdanens of 2.melanogaster t o

promote v i te l logenes i s , thereby promoting t h e maturation of oocytes

(Postlethwait 5 &., 1976: Handler and Postlethwait, 1978).

Methoprene was a l s o reported t o regulate acid phosphatase enzyme

(Postlethwait and Gray, 1975) and e rokth h o m n e production ( H i m a

e t & . t 1978a,b). Changes in t h e t i t r e of J H esterases due t o - juvenoid e f fec t were responsible for t h e changes during developnent

in many lepidopteran insec ts (Kramer 1974: P r a t t , 1975: De

Kort 5 e., 1977: Mane and Renbold, 1977: Brown 5 G., 1977: Sparks

e t &. , 1979: Armstrong et &. , 1980) and i n few dipteran insects - (Ter r ie re and Yu, 1973: Downer &., 1975: Retnakaran and Jo ly ,

1976: S c h m e v e l d 6 G., 1977).

' h e biochemical e f f e c t s of BPUs ( c h i t i n synthesis inh ib i tors )

have been extensively studied in re la t ion t o moulting process.

Inhibi t ion of c h i t i n formation with concomitant accurmlatitm of

precursors were achieved for t h e BPUs i n qypsy moths and s t a b l e f l i e s

i n v i t r o t i s s u e systems (Abdel-Nonem and M-, 1981: Nayer 6 g., - - 1981). Post and Vincent (1973) demonstrated reduced c h i t i n synthesis

in BPU t r e a t e d cabbage b u t t e r f l y larvae. Inhibi t ion of ch i t in

~yntheeis war well invest igated by Haj jar and Casida (1978) using

organ c u l t u r e s t rea ted with d i f lubenzuron and in v i t r o s tud ies have

also exhibited the same effect in housefly larvae (Van Eckl 1979).

The hypothesis that the chi t in synthetase a s actual biochemical

nuiety which interacts with toxicant was tested f i r s t in purified

ce l l f ree system of S t m x y s calcitrans pupal t i ssue by Meyer &

(1981), following the isolation of similar ce l l free system £ran the

gut of Tribolium castaneum (Cohen and Casida, 1980a,b). While dimilin

treatment was found t o increase protein synthesis in the larval

cut ic le of Musca domestics (Ishaaya and Casida, 1974) I such increase

was not noticed in the cut ic le of P.brassicae (Hunter and Vincent

1974) and Locusta (Clarke & &., 1977).

Chitin synthetase ac t iv i ty was much reduced when the enzyme

preparation was taken from a pretreated cabbage army worm (Mitsuir

e t g. , 1981). Thouqh diflubenzuron was inactive in fungal free - chi t in synthetase system, it was found t o inhibit chymotrypsin, a

protease which activates the system (Leighton & g. 1981)

Several miscellaneous aspects of mode of action of diflubenzuron

on spermatogenesis (Salama c., 19761, cuticular tanning (Hunter

and Vincent, 1974) and arres t of sclerotization (Zaner and Lipke,

1981) have a lso been studied. Diflubenzuron has been s h m t o have no

effect on photosynthesis o r leaf u l t r a structure eventhough it was

originally the result of search for herbicidal ac t iv i ty ( H a t z i ~ and

P.nnorl 1978).

BPUs have been shown t o produce other biochemical ananalies in

housefl ies and cabbage b u t t e r f l y which a r e not c r i t i c a l t o tox ic i ty .

Hyperactivity o f . phenol oxidase due t o diflubenzuron treatment was

observed by Ishaaya and Casida (1974) and explained by h e 1 6 &.I

(1978). A re la ted type of e f f e c t was show by Yu and Ter r ie re (19751

1977) on ac-lation of B-eabysone metabolizing enzyme. 0 'Neil l

e t &. (1977) d m s t r a t e d t h e absence of any change i n chit inaee - a c t i v i t y w e n in t h e presence of diflubenzuron. Mitl in fi. (1977)

studied t h e possible s t e r i l i t y e f f e c t s of diflubenzuron due t o

inh ib i t ion of DNA synthesis . 'The c y t o s t a t i c e f f e c t resu l t ing in t h e

disruption of imaginal d i s c developnent in f l i e s (Meola and Hayer,

1980) and J H mimetic e f f e c t with diflubenzuron have a l s o been noticed

(Retnakaran and Smith, 1975) but t h e cause of these e f f e c t s is not

ye t k n m . lhoogh vollnninous work has been done on t h e mode of act ion

and biochemical e f f e c t s of methoprene and diflubenzuron, s imi la r

s t u d i e s have not been c a r r i e d out extensively m new IGRs l i k e CMS

3031 (XRD-473).

2.2. Metabol im~ degradation and tox ic i ty :

Basic pathways f o r J H metabolism were f i r s t i l l u s t r a t e d by Slade

and Z i b i t t (1971, 1972). Subsequent Works on JH rnetabolian dealt with

expanding ear ly observations t o var ie ty of i n s e c t s (Ajmi and

Riddiford, 1971, 1973: Hurmck and Quistad, 1981). The unique

amtclbolim o f jwenoids and t h e i r metaboli tes have been examined i n

Page.. 1 2

many dipteran insects (Ajani and Riddiford, 1973: Yu and Terriere,

1975: H m c k & &., 1977). Eventhough information is ladring on the

metabolism of JH in many other arthropods JH appears to have very low

toxicity to mammals (Siddall and Slade, 1971, Slade and Zibitt,

1972).

Minimal metabolism of diflubenzuron was reported in salt marsh

caterpillar (MetcalE $- g. , 1975) and housefly (Ive and Wright,

1978). Essentially no degradation of diflubenzuron was found to occur

in boll weevil (Still Leopold, 1978). But subsequent study indicated

considerable degradation in the same insect (Chang and Stokes, 1979).

The metabolites of diflubenzuron have been analysed and the metabolic

process has been described by Sparks and Hammck (1979).

Difluhmzuron wag ~xtensivc?ly metabolized and readily excreted in

rats, shwp and cattle if given orally (Ivie, 1977: 1978).

Significant degradation of diflubenzuron by fish as well as other

canponents of aquatic ecosystem like fungi and bacteria has been

reported by Metcalf and Sanborn (1975) and Booth and Ferrell (1977).

On soil degradation studies, stability property of diflubenzuron was

found to be greatly dependent on the particle size of the soil (Still

and Leopold, 1978: Mansagar & &. , 1979). Envirormental fate and

photostability of diflubenzuron were found to be affected at high

tenperature and pH (Rum s., 1974: Schaefer and DJpras, 1977). Potential effectiveness and limited persistence of other IGRs have

been seen in different ecaloqical conditims (Eazrdder and Imckh~t t t

Page.. 13

1979; Mian and Mullat 1983: Schaefer & g., 1985: 1987). However, metabolic path ways and degradation of recently developed IGRs such

as OMS 3031 are wrly understood.

Dimilin has low acute mammalian toxicity and no effect on growth

and organ histopathology (Ferrell and Verloop~ 1975: Lewis and

Tatken, 1979: Miller &. , 1979) ) . Bishai and Stoolmiller (1979)

have demonstrat4 that diflubenzuron is neither cytotoxic nor

inhibits the synthesis of complex carbohydrates in mamatalian cells.

Eventhoqh very low mammalian toxiciy has been reported for the new

IGR OMS 3031 by the manufacturers, not much is known about its

toxicological aspects.

2.3. Organismal effects:

Knowledge of symptcms produced by a toxicant at different

developnental staqes of the target organism is important for several

reasone, because it provides an indication of the possible primary

site of action at the biochemical and physiological level. m e role

of juvenile hormones varies with the developnental stages and several

types of organism1 effects are &served. h33ryogenesis is disrupted

if JHAs are applied directly to the eggs. Various types of effects

ranging frcm ovicidal effects to delayed effects during post

embryonic lifa have been reported (Riddiford, 1971).

Page.. 14

Matolin (1970) has reported the ef fec ts of JH on eggs treated a t

d i f ferent developnental stages in Pyrrhocoris apterus. Ovicidal

e f fec ts of JH and JHAs have been reported in Rhodnius prolixus

( 1 lmchuk arid Ihvry, 1987) and Culex pipiens (Readio e t a l . , 1987). -- Inhibitory ef fec t of methoprene on the developnent of prepupal and

pupal stages of potato tubermoth Phthorimaea operculella has been

reparted recently (Prasad Reddy and Devaraj Urs, 1988). Impairment

a f t e r treatment of imidazole derivative with JHA act iv i ty has been

noticed in bombyx larvae (Akai and Rembold, 1989).

Morphological abnormalities due t o methoprene treatment were

seen with larva9 of many inspcts (Novak, 1966). Juvenoid treated

larvae result inq in suprnwnerary ins tar and larval-pup1 mosaics in

Hyalophora cecropia (Riddiford, 1971) have been observed. Treatment

of pupae with JHA resulted in pupal adult intermediates with many

deformities (Gilbert and Schneidemn, 1960: De Wilde g., 1971).

Deformities induced by JHA on treated adults of Togodem

granarium (Metawally and Landa, 1972: Chen and Wyatt, 1981),

Fyrrhocoris apterus (Masner &. , 1968) T~ibolium confusum (De

Veries and Brown. 1977) have been reported. JHA substi tution for

natural hormone resulted in termination of diapause (De Wilde c., 1971 : Chippendale, 1982).

Ihe effects of diflubenzuron follow a constant pattern in

bringing about disruption of ecdysis and factors relating to delayed

mortality. Laqe ntrmber of lepidopterans have been reported to show

moult disruption syndromes in larvae (Mulder and Gijiswijt, 1973;

Zabel and Ostojic, 1973: Salama c., 1976: Schmidt and Dorntlein, 19AO). Manifestations 01 an array of 'symptans at higher and lower

concentrations of BPU were noticed in larvae of western hemlock

looper, Lankdine fiscellaria lugubrosa (Sahota and Sheperd, 1975).

Delayed moultinq effects have been seen in the adult stage after

larval treatments of Eastern spruce budworm, Choristoneura fumiferana

(Brushwein and Granett , 1977). Fupal treatments of Stamxys

calcitrans with diflubenzuron caused incomplete emerqence with

various deformitiw (DP Loach & c., 1981). JH and JH mimics

produced deformities in the treated larvae of Calliphora vomitoria , pink bollworm, Pectinophora gossipiella, resulting in higher

inhibition in adult emerqence (Cawich ct., 1975: Arzone and blci,

1983) .

Ovicidal effects of diflubenzuron by treating adults topically or

through feeding have been reported in face flies (Pickens and Ce

Milo, 1977) stable flies (Ivie and Wright, 1978: Wright and Spates,

1978), house flies (Wright and Spates, 1976) horn flies (Kunz and

Bay, 1977) and tsetse flies (Kaplanis &., 1978). Variable

sensitivity of adult screw-worm flies with age was studied by Crystal

(19713). Pemnent ovicidal eEfects at high doses and reduced effect

at lower doses were seen with diflubenzumn treatment (Kunz and Bay,

1977: Rupes & gr '1977). However, no ovicidal e f fec ts were seen with

the treatment of BPUs on eggs of mosquito (Arias and Mulla, 1975a).

?he inhibitory e f f ec t s of direct treatment on hatching of

pipiens eggs with diflubenzuron (Miura, & &, 1976) and Tribolium

castaeneum eggs with d i substituted BW compounds (Saxena and.Mathur,

1981) have been reported. Treatment of adults with dimilin was found

t o have ovicidal e f fec ts on Culex t a r s a l i s and B t a e n i o r h y n c h u s

(Miura et &., 1976).

In scme lepidooterous insect larvae, fa i lure in feeding with no

obviws morphological abnormalities has been observed when treated

with dimilin (Zabel and Ostojic, 1977: Abid %&., 1978). In other

cases t r ea tm~n t of dimilin caused inabi l i ty in larvae t o chew and

inqest the f d due t o un~~snal position of mouth parts (Brushwin,

1980).

Effects of RPUs on beetles have been characterized as disruption

of moult a s well as reproduction (Mulder and Gijswijt , 1973). Contact

e f fec ts leadinq t o ovicidal effect caused by diflubenzuron treatment

have been hiqhliqhted in many coleopteran insects (Neal, 1974: Earle

e t a l . , 1978: Moore g., 1978) --

Treatment of aquatic habitat of mosquitoes with BPUs resulted in

larval mortality during moulting (Mulder and Gijswijt , 1973) or

formation of larval pupal intermediate (Mulla g. , 1975).

Malformation of pupae leading either to imnediate death or delayed

mortality during unsuccessful emergence has been reported in

g.quinquefasciatus, Ae.aegypti and An.stephensi wad and Mulla,

1984b) Malformation in adult mosquitoes has been noticed by Dame

a1.(1976) and Self pt g.(1970). -

Morphoqenetic effects ca~lsed by IGRs include immobile, stiff

larvae and elonqatd pupae in house flies (Wright, 1975: Rupes &

al., 1977: El-Khodary &. , 1979: Back 5 &. , 1983). Awad and - Mulla ( 1984a) have als? observed morphqenetic aberrations such as

larviform puparia, rod like and C-shaped puparia in house flies

treated with an TGR cyromazine. Treatment of tsetse fly adults with

~liflubmzuron shnwod characteristic moult deformities on the larvae

extruded from t.hm ((Jordan and Trwern, 1978: Kaplanis &. , 1978).

Treatment of black fly larvae with dimilin produced deformities in

the larvae and inhibited adult emergence (Lacey and Mulla ,1978:

McKague and Pridmre, 1979). Stable fly adults also shoved

abnormalities and hiqher susceptibility to diflubenzuron (Sclnnidt and

Kunz, 1980).

Diflubenzuron and other chitin synthesis inhibitors have induced

morphqlenetic aberration in adult3 cockroaches with twisted wings

(Yonker e., 1985: Singh & &. , 1985). Morphogenetic effects with

increaod melanination of adultoids have been ohserved in G e m n

cockroaches when exposed to various formulations of methoprene and

Page.. 1 l

other JHAs (Das and Gupta, 1974: Riddiford & 1975). Moribund

nymphs had concave flattened abdomensl sticky bodies due to body

fluid leakage and malformed wings When nymphal German cockroaches

were reared on diet treated with XRP-473 (Mark and Bennett, 1989).

Information available on the morphcqenetic effects of XRD-473 on

vector mosquitoes is rare.

2.4. Effects on reproduction:

The knowledge gained by studying the organismal effects of IGRs

would greatly aid in identifying the effects at the population level

by affecting various physiological processes like oviposition,

reproduction, etc.

Treatment of JHAs blocked ehryonic developnent in many

agricultural pests (Riddiford and Williams , 1967: Retnakaran and Grisdale, 1970). The application of juvenile hormone analogs among

agricultural pests resulted in sterility due either to blockage of

&ryonic developnent or resorption of dryos in viviparous species

or by inducing diapause in hcmoptera (Benskin and Perron, 1973:

Moreno, 1975: LeClant & &. 11976: Bonnemaison 1976; Sinqh and

Bindra, 1976; French and Reeve, 1979: Kozar and Varjas, 1976: Peleg

and Gothilf, 1981 ) and lepidoptera (Cawich & &. , 1975: Hi-, 1979; Shahsen and Omni, 1980: Yagi, 1980: El-Guindy & 2.1 1980arb: Chippendale and Yin, 1976: Fytizas and Mourikia, 1977)

Page.. 19

eoleoptera (Sehnal and Skuhravyr 1976: Schwneveld g &. I 1977:

Hoorel 1980: Ascerno & &. 1981) I diptera (Fi t izas and m i k i s t

1977: Lawrence & g. , 1978), hemiptera (Judson & &. t 1977) and

orthoptera (Fagmet 1979). Influence of J H and J H A mediated

reproduction has been repotted in many agr ic l tura l insects (Tobe and

Stay, 1980: Edverds, 1981). Application of chi t in synthesis

inhibitors resulted in reduced reproducticn and altered behaviour i n

sane agricultural pests (Chanq 1979: Grosscurt and Tipker, 1980:

Bariola I 1984).

Oogenesis and embryogenesis were inhibited due t o I(A treatment

in daneatica , Rhodnius prolixus and Sarc@aga bullata

(Siv~ubramanian, 1979: Kelly and Huebner, 1987). Under the influence

of IGR, reproductive potential was reduced in synanthropic f l i e s

(Bue'i 5 &. , 1980: Kostina g., 1986). Reproductive fa i lure due

t o topical application has also been observed in Chrysania albicep91

Gloasina morsitans mors i tans~ Sarcophaga bullata ( Jordan &&I

1979: Sivasubrmnian, 1979: Camrt 1987). Methoprene treatment

induced growth and responsiveness in ovaries of Ae.aegyptir (Shapin,

and Hagadorn, 1982). Increased egg production was noticed in

topically treated virgin fanales of Rhodnius prolixus wi th lnethoprene

(Ruegg and Davey, 1979). Treatment of adul ts with dimilin and

mthoprme s t h l a t e d ovarian dewlopnent i n house f l i e s vhich

reeu1t.d i n ao re frequent ovipos i t im than in untreated ones (Lincva

and Chunina, 19B). Precocious ovarian dareloplent was also observed

Page.. 20

in pitcher plant mo&uito Wjwmyia m i t h i i (O'meara and Lounibos,

1980). Treatment of adult house f l i e s with juvenile honnone mimics

produced s t e r i l i t y in both males and fenales (Elorgan and Labricaplet

1971). Treatment of male screw worms Cochilania haninivorax with

dimilin did not affect the v iabi l i ty of eggs but treatment of f e m l e s

did (Crystal, 1978). Accelerated egg developnent was occasionally

observed in Chironcmus thumni (Maa & al, 1983). Methoprene

stimulated the developnent of ovaries in treated Ae.aegypti (Feinsod

and Speilman, 1979) while it inhibited ovarian developnent in house

f l i e s by inhibit ing vitellogenesis (Styczynska and Sereda, 1979).

Chitin synthesis inhibitors and juvenoids considerably reduced

egg productim and f e r t i l i t y in Culex pipiens and Musca danestica

(Chang, 1979: Kelada & &. 11981). The ac t iv i ty of corpus a l l a t m and

its regulation by ovarian inhibitory feed back have been reported t o

cause reproductive e f f ec t s in methoprene treated Ae.aegypti and

Sarmphaga bullata (Feinsod and Spielman, 1979: Rossignol &.

1981). Methoprene, dimilin and other J H mimics induced s t e r i l i t y in

t s e t s e f l y (Clarke, 1982; Sameranayaka-Ramasany and Chaudhury, 1982:

Langley al, r 1987). Treatment of JHAs and ch i t i n synthesis

inhibi tors dras t ica l ly affected the reproductive parmeters i n

dipteran f l i e s result ing in t h e production of lesser nurber of

offspring (Cam1 , 1979; Nayar and Pierce, 1980: Angioy &. r 1983:

Heola and Readio, 1987). Thargh potential e f fec t of IGRs on the

rqrductiar of a n y agr icul tura l p.str has been extensively stud id^

Page. . Z I

such studies on insect vectors especially mosquitoes are sporadic.

CMS 3031 (XRD-473) has been reported t o cause infer t i l i ty in

treated German cockroaches (Demark and Bennett, 1989). Apart from feu

reports on the ccfttact and reproductive effects of this new CSI

(Ascher % &., 1986: b r r i e t , 19891, studies on the delayed effects

of C4.S 3031 on other biological processes of vector mosquitoes are

insufficient. Although researchers have exanined many aspects of

toxicity of IGRs on different insects, not much information is

accessible regarding the effects of these compcmnds on the entire

generation and on different population paranetera of vector

mosquitoes.

2.5. Control potential of IGRs:

Large scale field and laboratory evaluations of chitin synthesis

inhibitors and Juvenoids against leaf feeding and plant burrowing

agricultural pests have shown their selective application for control

of these pests (Ascher and NWyr 1974: Moore and Taft, 1975;

ElTantawit 1976: Ascher and Nerny, 1976a1b; Salema and Hagd El-Dint

1977: Flint, g., 1977, 1978: Johnson & &. , 1978: Carter, 1975:

Rappaport and Robertson I 1981 : Retnakaran, 1981 t 1982 1. Effective

control of exam stored product pests has been achieved by the

application of JflAs (McGregor and Krmer, 1975: De Vries and Brow,

1977: Kraner and McCregor, 1978: Amos ,t &. r 1978: Hoppet I 1981:

Springhetti and Franchi, 1981: Stockel and Edwards, 1981). XRD-473

was highly active in controlling the population of Heliothis

virescens and Sitophylus granarius (Leonard &I 1987). However,

the use of JHAa in controlling forest insects becanes econanically

unattractive as JHAa are needed in high dosages (Retnakaran and

Grisdale, 1970; Retnakaran and Bird, 1972: Retnakaran & &. 19771

1978; Robertson and Kifrball, 1979).

The use of IGRs becomes increasingly successful as they show

g o d prcmise in insect control operations. Control potential of

methoprene and its fomlations against vector and non veetornwq&to

species, C.pinquefasciatus, C.pipiens molistus~ C.taraalisl 2. peue speiser, C.pipiens ~ 1 l e n s 1 ~.guadrimaculatus~ An.ste&ensi,

Ae.aegypti , Ae.deritus, Toxorhnchites LUtiluS mtilus, has been - evaluated extensively both in the laboratory and field at application

rate ranging fran 0.560 g/ha under various mosquitogenic conditim

in different parts of the world (Jacob, 1972; Mulla %&.I 1974;

Mulla &g. , 1977: Pfuntcr, 1978: Boonluan Phanthwhinda and Pimpa Wattanachail 1978; Self & &. , 1978: Raj & 2. I 1978; Redantsever et &. 1979: Rathburn &. 1979, 1980; Ten Houten & &. I 1980: - Axtell 6 &. , 1980: Das & e. , 1981: Burgess and Chetwyn, 1983: Darriet % &. , 1985; Estrada and Hulls, 1986). Evaluation of IGR

activity of other juvenoids was also carried out in several species

of vector masquitoes (Tiwari and Saxena~ 1984: Wegner~ 1984; Schaefer

Page.. 23

Chitin synthesis ,inhibiting IGRs l i k e diflubenzuron and other

acylurea ccmpounds have proved t o be ef fec t ive against mosquitoes in

t he laboratory and in t he f i e l d (Mulla 6 e., 1975: Barker and

Boorml 1979: S h a m & &., 1979: Pridantswa, %&.I 1980: Ten

Houten st, 1980: Axtell &&., 19791 1980: Itoh, 1981; Bhakshi 6

a l . , 1982: El-Safi, 1986: Saxena and Kaushik, 1988: Alirzaw, 1986; - A l i and Nayar~ 1987). Other new BPU canpounds such a s AC-291898 and

XRD-473 with high insect growth regulating ac t iv i ty were a1.w

eff ic ient in controlling vector mosquitoes (Mulla and Darvazeh, 1988:

Mulla & &. , 1989: Darriet 1989: Amalra j and Velayudhan~ 1989)

Insect growth regulators showed pranise not only in controlling

mosquitoes but a l so other f l i e s vhich transmit disease pathogen of

human o r livestock. House f l y and s table f l y control had been

successful by using diflubenzuron in three different s t ra tegies of

application such a s surface treatment of animal excreta, treatment

through animal feed and treatment of barnyard surface (Might, 1974:

Wright and Harris! 1976: Wright & &., 1977, 1978). Effective

control of t s e t s e f l y population has been obtained with JHAa

treatment (Denlinger, 1975: Langley & &. , 1987). Excellent control

has been achieved by J H A treatment of c a t t l e f l i e s such a s s table

f l i e s Stanoxys ca lc i t rans (Matsunura, 1979) horn f l i e s , Haematcbia

i r r i t a n s (Barkerl 1977: Miller g. , 1979) c a t t l e grub1 Melophagus

winua, c a t t l e l i c e , Haemtopinus euryaternus (ChfxChrlain, 1979)

with JHAa tcpica l ly applied on cat t le .

Page. .24

Feed through treatment of IGRs has been found t o be highly

useful i n controlling f l i e s infesting poultry pew auch as blow fly,

Lucil l ia i l l u s t r i s (Christensen & &. 1979). Certain JHALI have been -- successfully used t o control the pohla t ions of house f l i e s through

c a t t l e and poultry feed (Wright, 1977: Lineava and Chunina, 1979;

Miller and Schidtmannr 1985).

Studies on chemical control of nuisance chironanid midges

population have also been carried out extensively using JHAa ( A l i and

Mulla, 1977: A l i $- &., 1978: A l i and Lord, 1980: Johneon and

Mullat 1981: Tabam, 1985: Takahashi etG.1 1985: A l i and Nayar,

1987: A l i and Chauduri , 1988).

Evaluation of diflubenzuron against black f l i e s has yielded good

r e su l t s in controlling these vectors in flowing waters (MaKague &

a l . , 1978: Lacey and Mulla, 1979). Control potential of dimilin - against horn f l i e s and t s e t s e f l i e s has a l so been demonstrated

(Barker, 1977: Kunz and Harris, 1978; Jordan and hewernt 19781

Jordan 2. 1979) .

Methoprene and other JHAs were found t o control effectively dog

f lea , Ctenoc@alides @ and Oriental f l e a Xenopsylla cheopis

other Ctenoce@ialides species (Riddiford, 1975: Ch&rlain and

Beckor, 1977: Cha th r l a in , 1979: O l m , 1985: Lang and Chanberlin,

1986). Ef foctivo control of imported f i r e ant has been obtained by

Page. .25

Cupp and OINeill (1973). Control of Pharaohs ant was effective by the

treatment of JHAs l i ke methoprene (Edwards, 1975: P h i l i p and

Thorvilson, 1989). Termite control using IQts have been denmatrated

by Howard and Haverty ( 1978 I 1979) I French & &. (1979) and French

and Reeve (1979).

The safety and potency of controlled release fornulatims and

other new fornulations of IGRs have been extensively evaluated

against mosquitoes (Wnn and Strong, 1973: S h a m & g., 1985).

Slow-release fornulatima and controlled release systems of IGRs have

been assessed in la rge sca le control opera t ims in order t o achieve

cost benefits (Mulla & &., 1977: Lewis1 1981; Kamei &&.I 1982;

Creeknur & &., 1982: Candelettil &&.I 1986: Linthicun &&.I

1989)

IGRs have shown high potency in controlling multi res is tant

s t r a in s of mosquitoes and f l i e s of medical importance (Cerf and

Qleoqhiou, 1974: Georghiou e t a1.1 1975; Geoqhiou and Lint 1975:

Rongsriym and Busvine, 1975: Merrel and Wagstaff, 1977; Oppenwrth

and Van der pasr 1977: Morton &&., 1985; Webb and Wildey, 1986:

Firstenberg and Sutherlandl 1982; Geerts and Deken, 1984; I4c Kenzie,

19871.

2.6. Developnant of resistance t o I-:

R.aiatwca dwalopmf~t t o 1- though observed i n saoe aped98

Page,. 26

(Rowland and w e l 1979) the proceaa waa slower and the accunulatim

of resistance was minimal (Georghiou, 1979: Brow and Brownl 1980:

Maan &.r 1981) Resistance or cross resistance t o insect growth

regulators waa probably due t o reduced penetratim of the IGRs l ike

diflubenzuron or a higher r a t e of metabolism in resistant individuals

(Plapp and Vinson, 1973: Georghiou & &. , 1978: Pirnprikar and

Georghiou, 1979: Grosscurt, 19801 1982: Sparks and Hammxk~ 1983:

Amin and m i t e , 1984: Walker and Wood, 1986). Hovever, no

documentation on the developnent of resistance t o CNS 3031 in target

popla t ion is available.

2.7. Effects on non-target organisms:

Methoprene and other JHAs were not found t o s h w any adverse

ef fects on various non target species of agricultural and

horticultural importance implying the sui tabi l i ty for practical

application (Zdarek and Haragsim, 1974: Singh and Bindra, 1976: Hodek

e t a l . # 1973: Jeppson & g., 1975: Barker and Waller, 1978). --

Studies on the re la t ive toxic i ty of JHAs on the pests and

parasites in the f i e ld of agriculture have a h m tha t t he i r adverse

ef fects a r e leea than those of broad spectnm insecticides (cXltrmr

1974: Granett & g.l 1975: Staal and Nasser, 1976; Ascerno & c., 1980). Diflub.nr;um e f fec t s on the p r d a t o r s and parasites of Crop

pasta am r.portod to be minimal Md tho rduc t ion agrp.r.d to be

Page.. 27

minor canpared t o the ef fec ts of conventional insecticidea (Ables &

al . I 1977: Kewer & g. 1977). Studies on the impact of dimilin on - cane forest insects along with t he i r parasite cap lexes have shown

reduction of parasite population (Madrid and Stewartl 1981)

Beneficial fauna including honey bees were unaffected by t h e

treatment of dimilin (Bocsor and Moore, 1975; Buckner e t a l , ~ 1975:

Mayer, 1977: Barker and Taber, 1977).

Though crustaceans l i k e Daphnia and spp. were found t o be

extremely sens i t ive t o dimilin and other insect growth regulators,

shrimps (Triopa and Eulirrmadia sp . ) , Copepods (Cyclops and D i a p t m

sp.) showed certain deqree of tolerance t o these canpounds in aquatic

environment (Miura and Takahashi, 1973,1974atb: Barber & &. , 1978:

Majori & g., 1981: Bircher and Ruber, 1988).

The disruptive e f f ec t s of different levels of IGR act iv i ty have

a lso been noticed in c r a b , (Forward and Costlow, 1978: Cardinal

e t &.I 1979). IGR treatment caused depression in the popla t ion of - other aquatic invertebrates such a s may f l y and dragon f l y naiade

(Steelman & &., 1975: A l i and Mulla, 1978: Farlow &&.I 1978:

Appereon & g., 1978). Non-target aquatic organisme l i ke copepod81

cladocerans~ notonectidat damael f l i e s and dragon f l i e s tha t coexist

i n lnoaquito breeding habi ta ts were not affected adversely by IGR

trmtmmta *ich w r e ef fec t ive againrrt mocrquitms (Miura and

T.kahacrhi~ 1974a: W l l a g., 1986: *lla and h?.wazehl 1988: Plulla

et &. , 1988). ~venthbugh reduct ion in the popllation of copepods and - clabcerans was observed a f t e r treatment of an IGR CME 1341 the

popla t ion recovered within few days (Schaefer & g., 1988).

Biocontrol agents l i k e Bacillus thuringiensis isralensis, the

planarian I Duqesia ap. and protozoan parasites, Asccqregarina

m l i c i s were reported t o have no adverse effect even a t high doses of

insect growth regulators (Levy and Miller, 1978: Nelaon, 1981;

Faqhal. 1982; Kostina and Dremsva, 1986). Toxicity of IGRs t o

mosquito nematode, Ranananemis mlicivorax has been found t o be

minimal (Levy and Miller, 1977: Winner &&., 1978).

Parasitoids of many insects have s h m varying levels of

tolerance t o insect growth regulators a t different doses ranging from

0.01-1.0 mg/l (Ables, & &. , 1975; Fashing and Sagan! 1979: Loof

e t g. 1979: Edvards, 1983; Ascerno a]-. 1983; Mohsen &. - 1986: Mourya and Soman, 1987; N e v t ~ ~ ~ t 1989). Investigations on the

biological and environmental dynamics of insect growth regulators on

other vertebrates l i ke f i sh , birds and mammal s have shown no

deleterious ef fects (Sacher, 1971: Mian and Mulla, 1982). The safety

of IGRs has been reported in many non-target macro fauna including

predatory f i sh (Miura and Takahashi, 1973, 1974a: Schooper, 1977:

Ellgard 5 &. 1979: Nelson & 2. 1986). Ecological apphoach t o

evaluate the potential impact of 1C;Rs m non-taqet fauna has been

Page.. 29

30311 a new chitin synthesis inhibitor, needs t o be studied for its

impact an the beneficial fauna which are involved in natural

regulation of insect species .

2.8. Sublethal effects:

Though the effects of sublethal concentrations of many synthetic

insecticides have been extensively studied in agricultural pests and

disease vectors (Adkisson and Wellsor 1962: Hodjat, 1971: Bariola,

1984: Alford and Holmes~ 1986)r similar studies with IGRs against

them insects are limited. Recently few reports have appeared on the

potential effects of JH, JHAs and BPU canpounds in suppressing the

populatim of ~ a n e insects of agricultural and public health

importance a t sublethal concentrations (Metwally & e., 1972: Jordan

et &., 1979: Gabcab, g &., 1981: Firstenberg and Sutherland~ 1981: - Kelada & &., 1981: Rob and Parella, 1984: Saxena and Kaushik,

1986: Hejasi and Granett, 1986: Saley and Aly, 1987: Robert and

Olson, 1989: Gujar and Mehrotra, 1989: Mauchanp & a. I 1989: Denark

and Bennett, 1989; Robert and Olson, 1989: Reid & &.I 1990).

However, there is a paucity of doamentation regarding systematic

studies of sublethal effects on vector mosquitoes. Since the

sublethal effects of IGRs are equally important a s their acute

toxicity, the knowledge on the consequences of sublethal e x p u r e s on

the biological and behavioural proceasea such as feedingl oviposition

and repm3uatian; i a a M o t i a l .

lbereforet the present investigation has been undertaken to gain

an insight in the following aspects:

1. Bioefficacy of OMS 3031 against Culexquinquefasciatus Say

(Pilariasie vector), Aedes aegypti Linn. (Dengue vector) and

Anopheles stephensi Liston (Malaria vector)

( i ) larvae

'( ii) pupae and

(iii)adults

2. Sublethal effects on the biology and behaviour of vector

mosquitoes:

(i) Hatching of eggs on direct treatment

(ii) Developnental duration and sex ratio in imtures

(iii) Feeding

(iv) Mating

(v) (Nipsition

(vi) Reproductive potential and

(vii) Longevity in adults

3. Asscssmnent of the effects on non-target organisms.

(i) Larvivorous fish

(ii) Predatory ineects

(iii) Cyclopoid copepods and Oatrsds

( i v ) ~;nnithid nematode