K20 FIELD ENTOMOLOGY

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Questions and Answers

What is the purpose of dissecting the head and thorax of mosquitoes?

To extract the salivary glands

What is the location of the oocysts in the mosquito?

Midgut

What is the parous rate of mosquitoes determined by?

Dissection of the ovaries

What is the magnification used to observe the sporozoites?

400x magnification Signup and view all the answers

What is the purpose of dissecting the abdomen of mosquitoes?

To extract the midgut and ovaries Signup and view all the answers

What is the location of the sporozoites in the mosquito?

Salivary glands Signup and view all the answers

What is the shape of the sporozoites?

Spindle-shaped Signup and view all the answers

What is the source of the schematic diagrams of the salivary glands and oocysts?

WHO, 1975 Signup and view all the answers

What is the primary purpose of collecting and preserving arthropods in field entomology?

For future identification and to overcome time constraints Signup and view all the answers

What is the main disadvantage of using potassium or sodium cyanide as a killing agent?

It is too toxic and dangerous to human Signup and view all the answers

What is the function of glycerol in preserving fluids?

To prevent arthropods from drying if the alcohol evaporates Signup and view all the answers

What is the concentration of ethyl alcohol commonly used as a preserving fluid?

70-80% Signup and view all the answers

Why is it important to prevent killing agents from wetting the insects?

To prevent damage to the insects' taxonomic characters Signup and view all the answers

What is the advantage of using ethyl acetate as a killing agent?

It is slower-acting than chloroform, but the killed insects will not be hardened Signup and view all the answers

What is the primary purpose of using laboratory techniques in field entomology?

To understand the morphology and behavior of arthropods Signup and view all the answers

What is the significance of close observation of preserved specimens in field entomology?

It provides an understanding of the form and function of arthropod bodies Signup and view all the answers

What is the method of collecting Pediculus capitis?

Cutting hairs from the head Signup and view all the answers

What is the recommended solution for preserving nucleic acids in specimens?

Carnoy solution (95% ethyl alcohol + 45% acetic acid 1:1) Signup and view all the answers

How are scabies mites typically collected?

Piercing the skin at the end of a tunnel with a needle Signup and view all the answers

Why is it necessary to change the preserving fluid after a few weeks?

To maintain the quality of the preserving fluid Signup and view all the answers

What is the purpose of using a black plate in collecting Scrub Typhus Mites?

To attract the mites with its orange or yellow color Signup and view all the answers

What is the medium used to observe mites?

Hoyer's medium Signup and view all the answers

What is the primary purpose of using entomological pins in displaying adult insects?

To display and study the insect Signup and view all the answers

Where are Pediculus humanus lice commonly found?

In the chest and armpits Signup and view all the answers

What is the recommended material for writing data on specimen labels?

Pencil Signup and view all the answers

Where are Pthirus pubis lice commonly found?

In the pubic area Signup and view all the answers

What is the purpose of painting the storage box with naphthalene, chloroform, Beachwood, and creosote in a 6:1:1:4 ratio?

To prevent insect damage to the storage box Signup and view all the answers

What is the ideal location to pierce the entomological pin through the insect?

Middle thorax between the coxa and first segment of the leg Signup and view all the answers

What is the purpose of refrigerating the preserved specimen?

To store the specimen long-term Signup and view all the answers

What information should be included on a specimen label?

Collection date, location, and species identification Signup and view all the answers

What is the primary purpose of using a D-net in mosquito sampling?

To collect mosquito larvae from habitats such as lakes and rivers Signup and view all the answers

What is the function of the fine mesh screen in a Pint Dipper?

To filter out organic particles and plants Signup and view all the answers

What is the purpose of using a quadrat in mosquito sampling?

To provide a more accurate comparative population index of larvae Signup and view all the answers

What is the mechanism by which a CDC Light Trap captures mosquitoes?

By releasing a down draft produced by a motor and fan Signup and view all the answers

What is the primary function of a Mosquito Magnet?

To lure mosquitoes using a continuous stream of carbon dioxide and attractant Signup and view all the answers

What is the purpose of using a Laddle in mosquito sampling?

To collect mosquito larvae from the bottom of habitats Signup and view all the answers

What is the mechanism by which Human Landing Catches (HLC) work?

By using kairomones to lure mosquitoes Signup and view all the answers

What is the primary purpose of using an aspirator in mosquito sampling?

To capture adult mosquitoes resting on walls and furniture Signup and view all the answers

Study Notes

General Introduction

Entomological techniques include collecting and preserving arthropods, laboratory techniques, and field techniques.
Close observation of preserved specimens helps in understanding morphology, systematics, evolution, taxonomy, and developmental biology.

Laboratory Techniques

Killing agents used to kill insects include potassium or sodium cyanide, chloroform, ethyl acetate, and ether.
Ethyl acetate is slower than chloroform but preserves insect bodies better.
Killing agents should not wet the insects to prevent damage to taxonomic characters.
Preserving fluids include ethyl alcohol (70-80% concentration) with 30% glycerol to prevent drying.
Liquid formaldehyde can be used, but it hardens the specimen.
Carnoy solution (95% ethyl alcohol + 45% acetic acid 1:1) is recommended for preserving nucleic acids.

Pinning Adult Insects

Adult insects are pinned into display boxes (Schmidt box) for study.
Rust-free entomological pins or pins covered with black lacquer are used.
The pin is pierced through the middle thorax between the coxa and the first segment of the insect's leg.

Labelling Specimens

Labels should include collection date, location, and species identification.
Data is written with a pencil or Indian ink.
Labels for fluid-preserved specimens are written with a pencil or glued outside the tube.

Dissection of Mosquitoes

Dissection of the head and thorax is done to extract salivary glands.
Dissection of the abdomen is done to extract midguts and ovaries.
Oocysts in the midgut and sporozoites in the salivary glands can be observed.

Field Techniques

Techniques for collecting arthropods include pinning adult insects, labelling specimens, and dissection of mosquitoes.
Techniques for collecting lice, mites, and chiggers include:
- Cutting hairs and fibres from clothing
- Collecting mites from skin
- Using black plates to collect chiggers from vegetation
Techniques for collecting mosquito larvae include:
- Using a laddle to dip into the water
- Using a pint-dipper to collect larvae
- Using a D-net to collect organic particles and plants
- Using a quadrat to measure population index of larvae
Techniques for collecting adult mosquitoes include:
- Using aspirators (hand or backpack)
- Using CDC light traps with CO2 and down draft
- Using the Mosquito Magnet with CO2 and attractant
- Using human landing catches to monitor population changes

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