collecting and preserving arthropods

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Medical Diagnostic 1

ENTOMOLOGY

COLLECTING AND PRESERVING

Arthropods

Norhayati Ismail



Learning objectives

the method of collection

killing and preservation

Mounting

of arthropods



Introduction

increased challenges to preserve and enhanceenvironmental quality,

Reduce pesticide usage, increase crop productivity,control food costs, and increase trade in the globalcommunity.

Pest species are responsible for enormous economic

losses annually, attacking crops and ornamentalplants, causing damage to our food and clothing, andvectoring diseases that effect cultivated plants, ourpets and livestock, and ourselves.

the study of insects and their relatives is of increasingimportance.

WHY??



Cont

The behavior of insects and mites can be observedmost easily in their natural environments. However,many species, especially the smaller ones, must becollected and properly preserved before they can beidentified.

The identification of a particular insect or mite usuallyrequires examination of minute details of its anatomywith the aid of a hand lens or microscope.

Some specimens may require dissection or even

study with the electron microscope.



Equipment and Collecting Methods



Collecting methods : collector actively searches out the insects,

collector passively and permits traps to do the work. Basic Equipment - nets, aspirators, beating sheets, traps collecting net, killing bottles collectors carry a bag or wear a vest - store equipment. in the general collectors bag:

Forceps. Fine, lightweight

Vials containing alcohol or other preservatives Killing bottles of various sizes.- liquid killing agents are ethyl

acetate, ether, chloroform, ammonia water, cyanides Small boxes or containers for storing specimens Small envelopes for temporary storage aspirators

Absorbent tissue Notebook and writing equipment A strong knife for opening galls, A small, fine brush



Collecting nets come in three basic

forms 1) Aerial Net- Collecting butterflies and

other flying insects

2) Sweeping Net- Collecting butterfliesand other flying insects

3) Aquatic Net- Collecting aquaticinsects



Collecting net

A truck equipped with a large net.



A: 2.5 cm of plaster of parismixed with water into the

bottom of the jar and allow the

plaster to dry.Add killing agent

to saturate. Refill is possible.

B: for use of solid killing agent

KILLING JAR



Second method

place a wad of cotton or other absorbent material in the bottom of a jar, pour enoughliquid killing agent into the jar to nearlysaturate the absorbent material, and thenpress a piece of stiff paper on it or acardboard cut to fit the inside of the jartightly. The paper or cardboard acts as abarrier between the insect and the killingagent, keeping the latter from evaporatingtoo rapidly and also preventing the specimenfrom becoming entangled in loose fibers.



Among the liquid killing agents:

ethyl acetate (CH3CO2 C2H5), ether (diethyl ether, C2H5 O C2H5),

chloroform (CHCI3), and

ammonia water (NH4OH solution).

Ethyl acetate

is most widely used, extremely volatile andflammable and should never be used near fire.

the most satisfactory liquid killing agent, lesstoxic to humans . Although it usually stuns insectsquickly, it kills them slowly.



Aspirators and Suction Devices



Specimen Preservation

Insects and mites of all kindsmay be killed and preserved

in liquid agents, but it is first necessary to determine theadvisability of using a liquid

killing agent rather than adry gaseous agent.



Liquid Agents for Killing and Preserving

Ethanol mixed with water or isopropanol Isopropanol does not seem to harden

specimens as much as ethanol, and at least it is satisfactory in an emergency.

95 percent alcohol : Best agent for kill and preserve parasitic Hymenoptera

- prevents the membranous wings from becomingtwisted and folded, hairs from matting, and soft bodyparts from shriveling.

large numbers of insects are to be killed in a single

container, insect body fluids will dilute the alcohol the small flies, and mites, become stiff and distorted should be preserved in alcohol of a lower

concentration



Cont Formalin (formaldehyde) solutions should not

be used because the tissues becomeexcessively hardened

Larvae of most insects should be collected inalcohol and subsequently killed in boiling

water to fix their proteins and prevent themfrom turning black.



Temporary Storage of Specimens

Refrigeration and Freezing

Dry preservation

Papering

Liquid Preservation



Refrigeration and Freezing

Medium to large specimens may be left in tightlyclosed bottles for several days in a refrigeratorand still remain in good condition for pinning aswill smaller specimens if left overnight.

Some moisture must be present in the containersso that the specimens do not become freeze-dried, but if there is too much moisture, it will

condense on the inside of the bottle as soon as it becomes chilled.



Absorbent paper placed between the jarand the insects will keep them dry.When specimens are removed for

further treatment, place themimmediately on absorbent paper toprevent moisture from condensing onthem.



Dry preservation

It is standard practice to place many kinds of insects in small boxes, paper tubes, triangles, orenvelopes for an indefinite period, allowing themto become dry. It is not advisable to store soft

bodied insects by such methods because theybecome badly shriveled and very subject tobreakage.

To insure that specimens do not slip from one

layer to another, cut pieces of absorbent tissue,glazed cotton, or cellucotton a little larger thanthe inside of the container..



Place a few layers of this material in the bottom of the container, then a few insects (do not crowd

them), then more layering material, and so on untilthe container finally is filled. If much space is left,use a little plain cotton, enough to keep the insectsfrom moving about but not enough to produce

pressure that will damage them.

To prevent parts of the insects from getting caught in the loose fibers, use plain cotton only for thefinal layer. Insect parts are very difficult to extract from plain cotton without damage



Papering

Papering consists of placing specimens with thewings folded together dorsally (upper sidestogether) in folded triangles or in smallrectangular envelopes of glassine paper, which

are the translucent envelopes familiar to stampcollectors.

Glassine envelopes have become almost universally used in recent years because of the

obvious advantages of transparency and readyavailability.



Papering of lepidoptera



Mounting Specimens

To handled and examined with the greatest convenience and with the least possibledamage

Enhance the value of a collection

Specimens to be prepared for a permanent collection may be fresh, that is, their bodytissues not yet hardened or dried; or theymay have been in temporary storage andmust be specially treated before mounting.

Dry specimens usually must be relaxed, andthose preserved in liquid must be processedso that they will dry with minimal distortion orother damage.



(1) OrthopteraPin through back of thorax to right of midline ( AB). For display purposes, one pair of

wings may be spread as shown, but manyorthopterists prefer to leave wings folded becauseof limited space in most large collections (seeBeatty & Beatty 1963).

(2) Large HeteropteraPin through triangularscutellum to right of midline (C). Do not spreadwings. In Reduviidae, Coreidae, and other slender

forms, pin through back of prothorax to right of midline.



(3) Large Hymenoptera and DipteraPin throughthorax between or a little behind base of

forewings and to right of midline (D). legs shouldbe pushed down and away from thorax, and wingsturned upward or sidewise from body. Wings of most Diptera will flip upward if specimen is laid on

its back before pinning and pressure is appliedsimultaneously to base of each wing with pair of blunt forceps. Wings should be straightened if possible so venation is clearly visible. Folded or

crumpled wings sometimes can be straightened bygentle brushing with a camels hair brush dippedin 70 percent alcohol. For Hymenoptera wings,Petersons XA mixture (xylene and ethanol, equal

parts by volume) is recommended.



(4) Large ColeopteraPin through right wing cover near base such that the pin

exits through the metathorax (between themiddle and hind legs) (E). Do not spreadwings.

(5) Large Lepidoptera and OdonataPinthrough middle of thorax at thickest point (F) or just behind base of forewings (G)



Cont

Mounting Wings Wings of many kinds of insects can be

mounted on microslides for detailed study

or photography. Wings are bleached by immersion in an

ordinary laundry bleach (sodiumhypochlorite solution). - for study of the

venation.



Cont

Mounting Larvae The study of the immature stages of many

insects is of great importance for

identification purposes, but specialtechniques are usually needed because of their soft cuticle.

The larvae of Diptera, Coleoptera,

Lepidoptera, and many other groups arebest killed in boiling water because it leaves them in good condition for criticalexamination.



GENER AL GUIDELINES FOR WHERE TO LOOK FOR ARTHROPODS

Aquatic Habitats(streams, ponds, pools, rain puddles, standing water.)

In the air: adult dragonflies, damselflies, mosquitoes,mayflies

Surface: water striders, whirligig beetles

In still water: mosquito larvae and pupae, beetle larvae andadults, water bugs

In fast moving water over rocks: caddis, dobson fly larvae,beetle adults

On or in the bottom: water bugs and beetles (both resting),mayfly, damselfly, and dragonfly naiads, black fly larvae,caddisfly larvae (in protective case)

In plants in water: Odonata naiads, bugs, beetles Tools: metal kitchen strainer, aquarium fish net, shallow pan,

gallon jar. Wear old shoes!



ContGround Habitats

In the soil: tiger beetle larvae, ant nests, wasps andbees, burrowing spiders, doodle bugs (ant lionlarvae)

Beneath stones: ants, beetles, beetle larvae, spiders,scorpions, sow bugs, centipedes

In leaf litter: sow bugs, springtails, beetles,centipedes, millipedes

On surface of the ground: beetles, grasshoppers,velvet ants, ants, flies

Tools: insect net, forceps, small vials, trowel, sifter(strainer will do)



Cont Plant Habitats

On the plant : caterpillars, beetle larvae and adults,aphids, scale insects, leafhoppers, tree hoppers,preying mantids

On the flowers: bees, wasps, various flies, beetles,spiders

Inside the plant : larvae of beetles (in and on thewood), leaf miners (in leaves), ants (in cavities), gallforming insects (flies, wasps and some aphids)

Tools: insect net, forceps, small vials, pruners



ContWoodland Habitat

Many kinds of flies, wasps, bees, ants, butterflies,etc.

Open Field

Many treehoppers, spittle bugs, beetles, wasps, ants, bees,butterflies, flies, spiders, etc.

Living on Other Animals Permanent visitors: biting lice, chewing lice, beetles, some

moth larvae Temporary visitors: mosquitoes, horse flies, black flies, fleas,pseudoscorpions, ticks, mites



TECHNIQUES IN DETERMINING THEPARITY OF A MOSQUITO

Step 1 Capture mosquitos. This is best achieved by a gravid

trap, a fan-and-net contraption that is best locatedabove a pool of stagnant, festering water. The

mosquitos are drawn to the water to lay their eggs,and are then sucked up by the fan into the net,where they can't escape.

Step 2

O

nce captured, tie off the net and throw it into afreezer, so as to kill the specimens. Even withindustrial freezers, this tends to take at least fifteenminutes: any less and they might revive on theoperating table, and fly off. Give them a half an hourto be on the safe side.



Cont

Step 3 Now frozen, retrieve the mosquitos - the fresher the

better. Place a female specimen on a clean slide witha dollop of diluted water. This is done to prevent excessive dryness.

Step 4 Obtain a very fine needle - ideally a minuten needle,

which is a brand of needles that is specially-made foruse in laboratories. Under a microscope, place the

needle firmly in-between the second and thirdabdominal segments from the posterior (the rearend) of the specimen.



Cont

Step 5 Slowly, slide the needle out and away from the

mosquito body. Fragile mosquito innards will bedrawn outwards, which under the microscope willresemble extraordinarily fine pasta. The ovaries

should tumble out with the rest of these organs, andwill be opaque and globular.

Step 6 Scrutinize the extent to which the mosquito's

fallopian tubes are gnarled and twisted.Relativelyuncurled tubes are the telltale sign of a mosquito that

has never before given birth. The more knotted thesetubes, the more times this mosquito has laid a batchof eggs.



THANK YOU

collecting and preserving arthropods

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