Entomology MT1 REVIEW

What are the three main body regions of an insect?

Head, thorax, and abdomen.

What are the three pairs of insect legs called by position?

Forelegs, midlegs, and hindlegs.

How many legs and antennae does a typical insect have?

Six legs and two antennae.

How many insect species are estimated in the filled study guide?

About 3.5 million.

What annual cost to world agriculture is associated with the spread of invasive pests and pathogens in the guide?

Potentially about $540 billion per year.

What animal is identified as the world's deadliest, and what annual death estimate does the guide give?

Mosquitoes; about 725,000 deaths per year.

What are four routes of Chagas disease transmission listed in the guide?

Infected triatomine bug feces entering through a bite wound; contaminated food swallowed; congenital transmission from mother to fetus; and contaminated blood transfusion.

Which mosquito is named as a pollinator in the guide?

Toxorhynchites rutilus.

What four factors are listed as contributors to insect decline?

Biocides, habitat loss, commercial harvesting, and invasive species.

Which invasive plant and threatened species are paired in the sagebrush-steppe example?

Scotch thistle and the greater sage-grouse.

Why does Scotch thistle matter for the greater sage-grouse example?

It can degrade sagebrush-steppe habitat and affect biodiversity.

How does the guide define evolution?

A change in gene frequency in a population.

How does the guide define natural selection?

Environmental factors that cause differences in survival and reproduction.

What human-driven pressures are listed as selection processes affecting insects?

Habitat destruction and insecticides.

What beneficial human-directed selection examples are listed?

Breeding and biological control.

During what period did giant insects live, according to the guide?

From the late Carboniferous to the late Permian.

What two factors are listed to explain giant insects?

Higher atmospheric oxygen (about 30%) and the absence of flying vertebrates such as birds and bats.

What were hell ants (Haidomyrmecinae) adapted to do with their mandibles?

Use specialized vertical mandibles to impale prey.

Why did hell ants' specialized mandibles become a disadvantage?

Their specialization could prevent them from feeding when their food source changed or adapted.

Did insects originate in marine or terrestrial environments, according to the guide?

Terrestrial environments.

What traits are listed as contributors to insect evolutionary success?

Small size, a tough exoskeleton, and flight.

What does Neoptery refer to, and what date is associated with it in the guide?

The ability to fold and flex wings along the back; about 315 million years ago.

What is the difference between Pterygota and Apterygota?

Pterygota are winged insects; Apterygota are primitively wingless insects.

Why can flight increase insect diversity and success?

It improves mobility, access to patchy resources and habitats, and the ability to evade predators.

What are three ways insect wings can be modified or used together?

Forewings may protect hindwings (for example, tegmina or elytra); forewings and hindwings may be coupled; or hindwings may be reduced to halteres in flies.

What are elytra?

Hardened, modified forewings that protect the hindwings.

What are alae?

The true flight wings, usually the hindwings.

What are tegmina?

Leathery or parchment-like modified forewings that protect the hindwings.

What are halteres, and which order has them?

Reduced hindwings used for balance; they occur in Diptera (flies).

What is the benefit of complete metamorphosis for adults?

Adults can use different food sources and habitats from larvae.

What are the three broad types of insect metamorphosis?

Ametabolous (little or no metamorphosis), hemimetabolous (incomplete metamorphosis), and holometabolous (complete metamorphosis).

What is a nymph?

An immature stage of an insect with incomplete metamorphosis; it generally resembles a small adult.

What is a larva?

An immature stage of an insect with complete metamorphosis; it usually looks different from the adult.

What is an instar?

A developmental stage between two molts.

What is a pupa?

The transformation stage between larva and adult in complete metamorphosis.

What three factors contribute to reproductive rate in the guide?

Fecundity, longevity, and generation time.

What is biogeography?

The study of species and ecosystem distributions across geographic space and geologic time.

Why is insect biogeography harder to interpret today?

Human habitat disturbance, human-associated insects and parasites, agricultural transport of insects and host plants, and deliberate movement of organisms blur natural distributions.

What are the three main layers or regions of the insect body covering named in the guide?

Epicuticle, procuticle, and epidermis.

How many tarsal segments are stated for each leg in the guide?

Five.

What is the coxa?

The first segment of an insect leg, attaching the leg to the body.

What is the prothorax?

The first thoracic segment; it bears the forelegs.

What are the three main parts of an insect antenna?

Scape (base), pedicel (second segment), and flagellum (remaining segments).

Name the antennal forms listed in the guide.

Filiform, moniliform, clavate, serrate, pectinate, flabellate, geniculate, plumose, and aristate.

What does a lamellate antenna look like, and what example is given?

It has plate-like lobes; the guide illustrates it with a cockchafer. The guide also labels it “flabellate,” so check the lecture slide for the instructor's exact term.

What is an open cell on a wing?

A wing cell that is not completely enclosed by veins.

What wing-cell examples are marked closed in the guide?

The first M2 cell and the first R3 cell.

What are jugal coupling, frenulum, and hamuli?

Structures that couple forewings and hindwings during flight; frenulum and hamuli link wings in some groups, while jugal coupling uses the jugal area.

Where does the guide place the frenulum hook?

On the forewing; verify this against the labeled lecture diagram because the location can depend on how the diagram is described.

What does “deciduous wings” refer to in termites and ants?

Wings that are shed after the reproductive dispersal flight.

What is the terminology caution for Dermaptera forewings?

The guide says “elytra,” but earwig forewings are more commonly called tegmina; check the instructor's slide wording for the exam.

What are tergites and sternites?

Tergites are dorsal abdominal plates; sternites are ventral abdominal plates.

What is an ovipositor?

A female structure used to lay or place eggs.

What is an aedeagus?

The male copulatory organ.

What do dorsal, ventral, and lateral mean?

Dorsal = toward the back/top; ventral = toward the belly/bottom; lateral = toward the side.

What four neuron or neurosecretory cell categories are listed in the guide?

Sensory neurons, interneurons, motor neurons, and neurosecretory cells.

Name the insect neuroendocrine organs or cell types listed in the guide.

Corpus cardiacum, corpus allatum, prothoracic gland, and Inka cells; the guide also mentions the ovary.

What is insect hemolymph?

The circulating body fluid of insects, functionally analogous in some ways to blood.

What are three functions of hemolymph listed in the guide?

Clotting, storage and distribution of nutrients, and transport of materials; it rarely transports oxygen or carbon dioxide.

What are taenidia?

Spiral or ring-like thickenings of the tracheal cuticle that help keep air tubes from collapsing.

What is the difference between open and closed tracheal systems?

An open system connects tracheae to the outside through functional spiracles; a closed system lacks open spiracles and exchanges gases across the body surface or specialized structures.

What are the broad functions of the insect foregut, midgut, and hindgut?

Foregut: ingestion, storage, and grinding; midgut: digestion and absorption; hindgut: water and ion regulation, further absorption, and excretion.

Which gut regions are shed during a molt, according to the guide?

The foregut and hindgut linings; the midgut lining is not shed with them.

What is frass?

Insect excrement.

How do ammonia and uric acid differ as nitrogenous wastes?

Ammonia is highly toxic and requires abundant water to excrete, so it is common in aquatic insects. Uric acid is less toxic and conserves water, so it is common in terrestrial insects.

What is a diploid zygote?

A fertilized egg with two sets of chromosomes, one from each parent.

What is parthenogenesis?

Development of offspring from an unfertilized egg.

What is a spermatophore?

A package or capsule containing sperm that is transferred to a female.

What is mitosis?

Cell division that produces two genetically similar daughter cells with the same chromosome number as the parent cell.

What is meiosis?

Cell division that produces haploid reproductive cells with half the chromosome number.

What is the spermatheca?

A female reproductive structure that stores sperm after mating.

What is an ovary?

The female reproductive organ that produces eggs.

What lab-style directions should you recognize on an insect specimen?

Dorsal (top/back), ventral (underside), and lateral (side view).