Ent302 Lab Exam 2

post-embryonic development

“egg” → (eclosion) → 1st instar (1st stadium) → “molt” → (teneral) → exuviae + 2nd instar

egg

developing embryo still in chorion

eclosion

hatch

instar

the beastie, itslelf

stadium

refers to time; length of time an insect spends as a specific instar

molting

apolysis → (pharate) → ecdysis (ecdysial lines) → exuviae + next stage ...

teneral

1. sclerotization (post-teneral) involves quinone tanning
2. arthropodins → sclerotins
3. differentiation of procuticle into exocuticular and endocuticular layers (only exocuticle is “tanned”)
4. excuivae (shed skin)

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insect immediately following ecdysis, when the new cuticle is soft, flexible, and light colored; insect resembles an albino

* at this time, most insects gulp air and/or water to expand the cuticle before it hardens and returns to its typical color

apolysis

“to loose”

old cuticle loosens away (separates) from epidermis

pharate

* shroud-like covering of old cuticle over new, developing cuticle
* refers to period of time between apolysis and ecdysis

ecdysis

“an escape”, “slipping out”

ecdysial lines

* aka ecdysial sutures
* weakened areas aling which the old exoskeleton generally splits
* commonly occur on the dorsum of the insect in the region of the head/thorax

types of metamorphosis

ametabolous

hemimetabolous

paurometabolous

holometabolous

ametabolous

* paraphyletic
* no special name for instars and number is indeterminate
* anatomically similar to adults
* habitat similar to adults
* taxa: apterygotes

hemimetabolous

* polyphyletic
* immature = naiad
* \~15-20+ instars
* +/- anatomical similarities
* -- habitaat similarities
* taxa = Pterygota: “paleopterans” +Plecoptera

paurometabolous

* paraphyletic
* immature = nymph
* \~5 instars
* anatomically similar to adults
* habitat similar to adults
* taxa = Pterygota: “polyneopterans” (minus Plecoptera) + Paraneoptera

holometabolous

* larva(e) → pupa(e)
* \~3-6 instars
* not anatomically similar to adults
* habitat not similar to adults
* taxa = Pterygota: Holometabola

meroblastic cleavage

mitotic division of only the nuclei and nucleoplasm that takes place during egg development, and is permitted due to the copious amounts of nutritive yolk protein that most eggs possess

holoblastic cleavage

the division of the entire egg during early cleavage due to eggs of some hexapods, like Collembola, containing much less yolk

oviparous

embryonic development characterized by eggs being laid, and then undergoing further cellular differentiation and development apart from the parent before eclosion occurs (hatching)

ovoviviparous

development in some groups, especially certain types of flies, wherein the fertilized eggs are held within the female until they are ready to hatch

* most commonly, the egg continues to be nourished by the yolk it contains

viviparous

additional means developed by a few species for nourishing the larvae as they develop within the female

* various structural specializations have evolved such that the eggs eclose and the larvae subsequently receive at least some nourishment directly from the parent
* type of embryonic development characteristic of mammals

embryogenesis overview

* oviparous: development = apart from parent; nourishment = yolk
* ovoviviparous: development = within parent; nourishment = yolk
* viviparous: development = within parent; nourisment = at least in part from female

polyembryony

* found in a few groups of insects
* a single egg develops into from 2-many embryos
* most commonly associated with endoparasitoid wasps that have small, relatively yolkless eggs possessing specializations for attaining nourishment from the host

parthogenesis

non-fertilized ovum development

degree of dependency upon parthenogenic development

* obligate: parthogenesis is the sole means of reproduction and males are unknown
* facultative: under specific circumstances, ova develop parthogenetically in absence of fertilization
* cyclical: in certain groups of insects (some aphids, gall midges, and gall wasps), a regular alternation of bisexual and parthogenetic generations is known to occur

sex of parthenogenetic offspring

* arrhenotoky
* thelytoky
* amphitoky

arrhenotoky

* =haplodiploidy
* only males produced; females are produced bisexually from fertilized ova and are diploid
* this type of sex determination is typical for the Hymenoptera (bees, wasps, etc) and also some Thysanoptera (thrips) and the beetle, Micromalthus

thelytoky

only females produced; most common type of parthenogenesis

amphitoky

* =Deuterotoky
* both males and females are produced

types of mitotic division

* apomictic: the reductive phase of meiosis is absent; offspring carry a genetic compliment identical to that of the parent
* automictic: the meiotic division is normal, but two nuclei from the products of meiosis fuse, thus re-establishing a functional diploid condition
* both the parent and the offspring are diploid, but not necessarily of identical genetic composition

paedogenesis

in bizarre species of insects, the phenotypically immature stages are known to possesss mature reproductive organs

* more frequently these immature insects are parthenogenetic, and embryonic development is viviparous

first instar

an immature insect, immediately following eclosion

* normally feed and grow to the point where a molt becomes necessary, giving rise to the second instar and the excuvium of the first instar

incomplete metamorphosis

* immature stage (nymphs) grossly resembles adult except for absence of wings and smaller size
* wing development is external, starting with small wing buds or wing pads
* immatures typically occupy the same general habitat as adults and feed similarly

complete metamorphosis

* immature stages (larvae, pupa) usually very different from adult in general appearance; the larva is the active feeding stage while the pupa is a transitional form characterized by nearly complete internal and external re-arrangement of organs and structural features
* wing development internal, from dormant masses of cells, the wing Anlagen
* immatures frequently occupy a much different habitat than the adult; feeding strategy may be very different

ametabolous development

restricted to groups which continue to molt throughout adult life and are primitively wingless

paurometabolous development

* immature stages possessing “gradual” metamorphosis, = nymphs
* adults are typically einged, but some have lost them secondarily
* nymphs live in same environment as adults and have the same types of mouthparts and feeding habits
* wings develop as external wing pads, increasing in size through successive instars, only functional in the adult stage
* usually \~5 distinct nymphal instars preceding the adult stage

hemimetabolous development

* gradual metamorphosis wherein the immature stages, or naiads, are aquatic while the adults are terrestrial (aerial)
* wing development similar to paurometabolous species, but naiads possess special ventilatory organs adapted to aquatic existence
* foods of naiads vs adults is very different
* development often prolonged over an entire year or several, 15 or more instars common
* found in paleopterous Odonata and Ephemeroptera and polyneopterous Plecoptera

holometabolous development

* complete metamorphosis
* pupa may be housed in protective cocoon of silk or various other substances; or may be formed within the hardened exuvium of the preceding larval instar, which is common in asvanced flies, where entire entity = puparium
* characterizes orders making up the Division Endopterygota

taxonomic hierarchy

1. domain
2. kingdom
3. phylum
4. subphylum
5. class
6. subclass
7. infraclass
8. division
9. superorder
10. order
11. suborder
12. series
13. superfamily
14. family

insect taxonomy

1. kingdom - Animalia
2. phylum - Arthropoda
3. subphylum - Hexapoda

apterygote orders

* order Archeognatha
* order Thysanura

subclass Pterygota

The paleopterous orders:

* Order Odonata
* suborder Anisoptera
* suborder Zygoptera
* Order Ephemeroptera

apterygote taxonomic diagnosis

* chewing mouthparts
* antennae elongate, many segmented
* primitively wingless
* elongate caudal cerci and median caudal filament
* vestiges of segmental abdominal appendages (styli) present

apterygote binomics

* ametabolous
* indirect insemination (spermatophore)
* sexually mature females must mate subsequent to ecdysis, since spermathecal cuticle is lost

order Archeognatha (bristletails) taxonomic diagnosis

* compound eyes large, often contiguous dorsally
* 3 ocelli present
* mandibles elongate, monocondylic
* styli present on abdominal segments 1-9

order Archeognatha binomics

* uptake of water in certain species is through eversible vesicles located near abdominal styli; some species apparently survive on metabolic water, only
* feed saprophagously or on lichens and algae

order Thysanura (silverfish, firebrats) taxonomic diagnosis

* compound eyes greatly reduced or lacking
* ocelli usually absent
* mandibles dicondylic
* styli usually present only on abdominal segments 7-9

order Thysanura binomics

* some species found in extremely xeric habitats, others restricted to areas of high relative humidity
* feeding habits similar to Archeognata; household species commonly feed on starchy materials

subclass Pterygota taxonomic diagnosis

* Pterothorax of adults enlarged and highly modified to support flight
* adults bearing 1-2 pairs of wings, or secondarily wingless

subclass Pterygota binomics

* undergo definite metamorphosis; do not molt once sexually mature
* generally, direct insemination (copulation)

paleopterous insect orders (primitively winged insects)

taxonomic diagnosis:

* antennae of adults short, setaceous
* wings incapable of being flexed or folfed over the dorsum in repose
* wings with supernumerary venation

binomics:

hemimetabolous (naiads aquatic)

order Ephemeroptera (mayflies, wigglers) taxonomic diagnosis

* vestigial mouthparts (adults); chewing (naiads)
* adults usually with 2 pairs of subtriangular wings; mesothoracic wings much larger than those of metathorax; metathoracic wings sometimes strongly reduced or lacking; flight musculature largely indirect
* wings usually held upright when not in use
* tarsi of naiads 1-segmented; pretarsus bearing one claw (looks crab-like)
* gills of naiads plate-like or “feathery", dorsoventrally along abdomen
* naiads and adults usually with well-developed caudal cerci, also commonly possessing a median caudal filament

order Ephemeroptera binomics

* possess a unique developmental stage (winged) prior to reaching sexual maturity; initial winged stage is the subimago, sexually mature adult is the imago
* copulation commonly involves mating swarms
* some species possess paired gonopores
* adults generally non-feeding, short-lived; naiads primarily phytophagous or saprophagous
* anatomy of naiads highly correlated with specific type of habitat (adaptations for fast water; burrowing, etc)

order Odonata (dragonflies, damselflies) taxonomic diagnosis

* chewing mouthparts; labium of naiads highly modified, extensible
* adults with 2 pairs of elongate, membranous wings; flight musculature direct
* compound eyes large, well developed

order Odonata binomics

* male possesses secondary organ (2nd copulatory sternite) for sperm storage; female responsible for final transfer of spermatozoa
* naiads and adults predaceous

suborder Anisoptera (dragonflies)

taxonomic diagnosis:

* naiads lack tracheal gills; gas exchange assisted by heavily tracheated rectum
* wings of adults extend outstretched when not in use; mesothoracic wings considerably narrower than metathoracic wings near base

binomics: Odonata

suborder Zygoptera (damselflies)

taxonomic diagnosis:

* naiads possess leaf-like caudal tracheal gills
* wings of adults usually held upright over dorsum when not in use

infraclass neoptera

exopterygote orders

taxonomic diagnosis:

* not formally recognized, see binomics

binomics:

* nymphs ( or naiads, if Plecoptera) superficially resemble adults except for lack of functional wings and external genitalia, and body size, proportions
* wings develop externally from wing buds or wing pads
* immatures commonly occupy same habitat as adults and feed similarly (except Plecoptera)

superorder Polyneoptera

taxonomic diagnosis:

* chewing mouthparts
* antennae usually elongate, filamentous
* cerci commonly present
* nymphs generally possess ocelli
* Malpighian tubules numerous (except Zoraptera)
* only slight cephalization of nervous system (except Zoraptera)

binomics:

* paurometabolous (except Plecoptera: hemimetabolous)

order Blattodea (cockroaches, roaches) taxonomic diagnosis

* commonly 2 pairs of wings; mesothoracic pair somewhat leathery, those of metathorax membranous with pleated folds; some with wings reduced; some wingless
* body ovate, somewhat dorsoventrally flattened
* legs cursorial with 5-segmented tarsi

order Blattodea binomics

* roaches are omnivorous or generalized feeders which attain their greatest diversity in the tropics. A few species, however, are closely associated with humans (=synanthropic) and have a bad reputation, feeding on all sorts of things, contaminating household foods, and leaving their foul-smelling odor
* female roaches “package” clusters of eggs in a single leathery case, the ootheca, which is carried around for a period of time before being dropped. The somewhat rectangular ootheca can commonly be seen protruding from the end of the female’s abdomen in certain species

clade Isoptera (termites, part of Blattodea) taxonomic diagnosis

* antennae of moderate length, filiform to moniliform
* reproductive adults with 2 pairs of elongate, similarly shaped, membranous wings, or wingless
* compound eyes present or not
* legs ambulatorial, usually with 3- or 4-segmented tarsi
* generally small, soft-bodied insects

clade Isoptera binomics

* eusocial insects existing in highly complex colonies
* caste system with morphological specialization related to colonial functions: reproductives, workers, soldiers, nasute
* reproductives (king, queen) may be winged and generally have compound eyes; carry out reproductive functions
* workers (m or f) tend other castes (feeding, grooming), forage for food, and tend to maintenance of colonial structure
* soldiers (m or f), like workers, are sterile and lack compound eyes and wings. Defense function, as is true of the specialized nasute-type soldiers
* feed primarily on plant tissues rich in starches and cellulose; some cultivate fungi

order Mantodea (mantids, pre(a)ying mantis) taxonomic diagnosis

* commonly 2 pairs of wings; those of mesothorax somewhat leathery, especially near anterior margin; metathoracic wings membranous with pleated folds
* head triangular with large compound eyes
* prothoracic legs raptorial; all tarsi 5-segmented

order Mantodea binomics

* well-developed compound eyes and formidable looking prothoracic legs due to predaceous mode of existence
* camouflage also contributes to success of these voracious insects, and may involve coloration and/or anatomical modifications
* egg mass is a papery structure, and ootheca

order Dermaptera (earwigs) taxonomic diagnosis

* two pairs of wings with those of mesothorax short and heavily sclerotized (elytra); metathoracic wings broad, semicircular, membranous and folded fan-like beneath elytra, or wingless
* abdomen with large, heavily sclerotized, unsegmented, forceps-like cerci

order Dermaptera binomics

* generally omnivorous, some predaceous, several foreign species associated with animals (bats, rodents) may be ectoparasitic
* in some species, female cares for the eggs and early instar nymphs
* some (e.g. mammal associates) undergo viviparous embryonic development
* forceps-like cerci used in defense, manipulation of food, to assist with folding the large metathoracic wings, and in courtship and copulation
* males of some species possess paired gonopores

order Embiodea (web spinners) taxonomic diagnosis

* males usually with 2 pairs of membranous wings; females apterous
* tarsi 3-segmented; first tarsomere of prothoracic legs conspicuously swollen, modified for silk production
* cerci present

order Embiodea binomics

* variety of feeding habits, e.g., fungal spores, lichens, moss, bark
* often found gregariously in silken galleries within logs, etc
* some with brief maternal care of eggs and first instar nymphs
* parthenogenesis recorded in several species
* male is usually dispersal mechanism, leaving home “colony” to mate with female of another colony; males are short-lived and do not feed; they are commonly eaten by the female following copulation (die after it anyway)

order Zoraptera taxonomic diagnosis

* two pairs of membranous wings, or wingless
* compound eyes and ocelli present or not
* legs ambulatorial; tarsi 2-segmented
* cerci present
* Malpighian tubules reduced to 6
* cephalization of nervous system, with 2 thoracic and 2 abdominal ganglia

order Zoraptera binomics

* occur in decaying vegetative materials or in association with termite colonies
* feed on fungi and perhaps minute invertebrates
* just over 20+ species described, 2nd smallest order of insects
* often found gregariously, though apparently lacking any social organization

order Plecoptera (stoneflies) taxonomic diagnosis

* 2 pairs membranous wings; mesothoracic pair elongate and those of metathorax much wider; with pleated folds and expanded anal region
* abdomen commonly bearing 2 well developed cerci (naiads and adults)
* gills (naiad) commonly consisting of tufts of papillae, associated primarily with ventral aspect of thorax and perhaps abdomen
* tarsi 3-segmented; pretarsus bearing 2 claws

order Plecoptera binomics

* hemimetabolous
* gas exchange in naiads also occurs through integument; may lack gills
* naiads primarily phytophagous, some are predators
* adults are fairly short-lived and commonly do not feed; several have, however, been observed eating algae, lichens, and foliage

Superorder Paraneoptera

taxonomic diagnosis:

* more advanced groups possess sucking mouthparts
* most groups with reduced antennal length and segmentation
* cerci absent
* nymphs lack ocelli
* Malpighian tubules reduced to 4-6
* typically exhibit great amount of nervous system cephalization

binomics

* paurometabolous

order Psocodea (booklice, barklice, true lice) taxonomic diagnosis

* chewing mouthparts; labial silk glands
* antennae elongate, filamentous
* 2 pairs membranous wings; mesothoracic pair larger than those of metathorax; wings typically held rook-like over dorsum when not in use; or wings strongly reduced; or wingless
* commonly minute, soft-bodied insects
* head with swollen clypeal region (cheeks)

order Psocodea binomics

* feed on starchy materials, fungal spores, molds, etc
* possess sitophore-pestle in head; “swollen” frontoclypeal increases inner cranial surface area for muscle insertion (to operate pestle)
* parthogenesis common; some species develop viviparously

suborders Amblycera, Ischnocera, Anoplura (lice, chewing lice, sucking lice) taxonomic diagnosis

* wingless
* compound eyes reduced or absent; ocelli lacking
* antennae strongly reduced
* dorsoventrally flattened body

suborders Amblycera, Ischnocera, Anoplura binomics

* highly adapted to ectoparasitic life style; feed on birds and mammals
* tarsi commonly modified to grasp feathers of hair of host
* most are not only host specific, but also show high degree of preference for a particular region of the host’s body
* parthenogenesis is known to occur in some species

suborder Amblycera (chewing lice) taxonomic diagnosis

* head usually broader than prothorax
* antennae 4-segmented, capitate
* head grooved to receive antennae
* maxillary palpi present
* chewing mouthparts with mandibles horizontal

suborder Amblycera binomics

* most ectoparasites of birds; 2 species are associated with guinea pigs
* feed primarily upon feathers, hair, scales, and exudates from sebaceous glands

suborder Ischnocera (chewing lice) taxonomic diagnosis

* head usually broader than prothorax
* antennae 3-5 segmented, filiform
* head without antennal grooves
* maxillary palpi absent
* chewing mouthparts with mandibles vertical

suborder Ischnocera binomics

* includes 2 families, one is associated with birds and the other restricted to placental mammales (excluding humans)
* feeding habits same as Amblycera

suborder Anoplura (sucking lice) taxonomic diagnosis

* head narrow, usually much narrower than width of prothorax
* sucking mouthparts

suborder Anoplura binomics

* ectoparasites of mammals (including humans)
* feed on blood and serve as vectors of several important disease pathogens
* human body louse transmits two rickettsial diseases: epidemic typhus and trench fever; also a vector for relapsing fever (spirochaete pathogen)
* pubic louse or crab louse is another parasite of humans, but is not yet shown to be a disease vector

order Hemiptera (bugs, aphids, leafhoppers, etc)

taxonomic diagnosis

* sucking mouthparts
* compound eyes usually well developed; ocelli present or not
* 2 pairs of wings or wingless; rarely 1 pair of wings; wings may be reduced (brachypterous), especially in aquatic species

binomics

* large and diverse group, but many species are phytophagous

suborder Heteroptera (true bugs, bugs) taxonomic diagnosis

* beak originates from anteroventral region of head
* mesothoracic wings with basal portion leathery and distal region membranous (hemelytra)
* wings typically overlapping and folded flat over dorsum when not in use
* antennae usually elongate, filiform (terrestrial species) or short and concealed under sides of head (aquatic species)
* mesentron often divided into several chambers or sub-regions, each with specialized nutrient absorption functions

suborder Heteroptera binomics

* generally, a short, stout, 3-segmented beak is associated with a predaceous life style; elongate 4-segmented beak often indicative of phytophagous habits
* many species have scent glands which are commonly defensive in nature

family Corixidae (water boatmen) taxonomic diagnosis

* antennae short, usually conceal along ventral surface of head
* prothoracic tarsi oar-like or scoop-shaped , lacking terminal claws; metathoracic tarsi also lack claws
* beak broad, unsegmented

family Corixidae binomics

* aquatic species found in fairly quiet waters; active fliers, however, which can commonly be collected at light during evening hours
* largely omnivorous, using the prothoracic tarsi to scoop up algae, diatoms, and other plankton from bottom sediments

family Notonectidae (backswimmers) taxonomic diagnosis

* antennae short, usually concealed in grooves of head
* metathoracic tarsi lacking claws; prothoracic legs bearing terminal claws
* beak short, stout; well developed

family Notonectidae binomics

* aquatic predators; capable of inflicting a painful bite
* commonly swim on their backs, using the well-developed natatorial metathoracic legs as “oars”

family Belostomatidae (giant water bugs, electric light bugs) taxonomic diagnosis

* prothoracic legs conspicuously raptorial
* mesothoracic and metathoracic legs natatorial, with fringes of setae

family Belostomatidae binomics

* aquatic predators, feeding on other insects, small fish, tadpoles, and any other animals within their size range
* their highly musculated prothoracic legs are well developed for grasping while the short, stout beak is thrust into the prey
* digestion of prey begins outside of the belostomatids and is facilitated by means of proteolytic enzymes mixed with salivary secretions
* in a few groups, the female deposits her eggs on the dorsum of the male where they remain until eclosion
* electric light bugs name refers to the fact that the nocturnally active adults are strong fliers which frequently come to light

Family Gerridae (water striders) taxonomic diagnosis

* antennae usually longer than head, exposed
* preapical tarsal claws
* slender, elongate body and legs

family Gerridae binomics

* predaceous to omnivorous species found skating along water surface
* preapical attachment of tarsal claws helps keep legs (and body) from rupturing surface film
* several marine gerrids are among the few groups of insects to successfully compete in a salt water ecosystem, albeit on the surface

Order Orthoptera (grasshoppers, crickets, etc) taxonomic diagnosis

* commonly 2 pairs of wings; mesothoracic wings somewhat leathery; metathoracic wings membranoys with pleated folds, or wingless
* antennae typically elongate, filiform
* metathoracic legs usually saltatorial; all tarsi 3- or 4-segmented
* auditory organs often present

Order Orthoptera Binomics

* mostly phytophagous, numerous species are pests of crops
* sound in an important behavioral component for most species relative to territoriality, courtship, etc
* sound is also an integral part of speciation in many cases; species which are extremely difficult to identify on the basis of anatomical characteristics commonly display very different calling or “chirping” behavior

Family Acrididae (short-horned grasshoppers) taxonomic diagnosis

* antennae about 1/2 as long as body, or shorter
* tarsi 3-segmented
* ovipositor short
* auditory organs located laterally on 1st abdominal segment

Family Acrididae binomics

* acridids are phytophagous and may be demonstrated by the broad, heavily sclerotized mandibles which are adapted for biting off and grinding up pieces of plant materials
* many serious economic pests are included in this common group, including several of the infamous “migratory locusts”