BIOL 357 Entomology Comprehensive Review

Comprehensive vocabulary flashcards covering the morphology, development, evolutionary history, classification, and ecological importance of insects and hexapods based on lecture materials.

Apiculture

The practice of maintaining bee colonies in artificial apiaries for agricultural pollination and the production of goods such as honey and beeswax.

Sericulture

The commercial rearing of silkworms for the production of raw silk.

Lac

A resinous secretion produced by certain scale insects used commercially in adhesives, dyes, and furniture finishes.

Paratransgenesis

A bioengineering strategy that modifies symbiotic microbes within disease vector insects to inhibit the carriage and transmission of pathogens to humans.

Indicator Species

Organisms whose population health or presence reflects environmental conditions; for example, freshwater nymphs indicate water purity, while ground beetles indicate soil contamination.

Extirpation

Local extinction; a condition where a species is eliminated from a specific geographic region while continuing to survive elsewhere.

Community Homogenization

An ecological pattern driven by anthropogenic disturbance where widespread generalist insect species thrive and replace specialized local species across communities.

The Windshield Phenomenon

The anecdotal observation of a decline in dead insects accumulated on vehicle windshields, reflecting documented reductions in local flying insect biomass.

Phylogenetics

The study of evolutionary history and relationships among organisms inferred from heritable traits including morphology, amino acid sequences, and DNA.

Synapomorphy

A shared derived homologous trait inherited from a common ancestor that defines a monophyletic taxonomic rank or clade.

Polytomy

A node on a phylogenetic tree where more than two terminal taxa branch simultaneously, visually representing unresolved evolutionary relationships.

Carcinization

An example of convergent evolution within Phylum Arthropoda in which crab-like body plans evolved independently across multiple distinct crustacean lineages.

Pancrustacea

The clade grouping Hexapoda within Subphylum Crustacea, supported by shared crystalline cone eye structures (four cells), neuroanatomy, and homologous genes.

Ecdysis

The periodic shedding or moulting of the organic outer cuticle necessary for growth in members of the clade Ecdysozoa.

Ecological Morphospace

The theoretical multidimensional range of all possible morphological and functional traits, ecological roles, and habitats available to a taxon.

Heteronomous Metamerism

A body plan characterized by repeating structural subunits (segments) that are non-identical and specialized to bear different appendages or organs.

Tagmatization

The evolutionary specialization and grouping of adjacent body segments into distinct functional body regions termed tagmata (such as the head, thorax, and abdomen).

Devonohexapodus bocksbergensis

A fossil arthropod representing an evolutionary transitional form between marine crustaceans and early freshwater or terrestrial hexapods.

Superclass Hexapoda

The group of terrestrial arthropods characterized by three tagmata, three pairs of thoracic walking legs, three thoracic segments, no jointed abdominal legs, one pair of antennae, and Malpighian tubules.

Malpighian Tubules

Slender excretory and osmoregulatory tubes extending into the hemolymph from the insect digestive tract that filter metabolic waste.

Epicuticle

The outermost, non-chitinous thin layer of the insect exoskeleton that forms a protective, water-impermeable barrier.

Exocuticle

The rigid middle layer of the insect cuticle that undergoes sclerotization (protein cross-linking) and biomineralization for structural hardness.

Endocuticle

The soft, flexible inner layer of the insect cuticle situated directly above the living epidermal cell layer.

Sclerite

A hardened cuticular plate covering a body segment; includes dorsal tergites, ventral sternites, and lateral pleural plates joined by flexible membranes.

Hypognathous

A head orientation where the mouthparts are directed ventrally (downwards) with a vertical long head axis, ancestral to winged insects and suited for surface grazing.

Prognathous

A head orientation where the mouthparts are directed anteriorly (forward) with a horizontal long head axis, characteristic of predatory or burrowing insects.

Opisthognathous

A head orientation where the mouthparts are angled posteriorly (backward between the front legs), typical of piercing-sucking fluid feeders.

Ecdysial Line

A weakened midline seam of thin cuticle in the vertex of the head capsule that splits open to allow the insect to emerge during ecdysis.

Tentorium

The internal skeleton of the head capsule formed by four cuticular invaginations (apodemes) providing structural brace against compression and muscle attachment.

Pedicel

The second antennal segment situated directly above the basal scape, containing Johnston's sensory organ.

Sensillum

A specialized cuticular sensory organ composed of a hair or seta, an anchoring socket cell (tormogen cell), a trichogen cell, and sensory neurons.

Pterothorax

The collective wing-bearing thoracic region formed by the rigid integration of the mesothorax ($T2$) and metathorax ($T3$).

Saltatorial Legs

Hindlegs modified for jumping, characterized by an enlarged, muscle-packed femur and an elongated tibia.

Pulvilli

Adhesive pads covered in minute hairs situated on the pretarsus that secrete sticky fluid to allow climbing on smooth vertical surfaces.

The Entognatha

A basal clade of wingless hexapods (Classes Protura, Diplura, Collembola) defined by mandibles and maxillae retracted inside a gnathal pouch within the head capsule.

Class Protura

A class of minute ($<2.5\,mm$) eyeless, antennaless entognathans possessing pseudoculi, fluid-sucking stylets, sensory forelegs held forward, and anamorphosis.

Anamorphosis

A developmental pattern in which juveniles hatch with fewer abdominal segments ($8$ in Protura) and add one segment during each moult until reaching the adult count ($12$).

Class Diplura

A class of blind entognathans with long moniliform antennae, $11$ abdominal segments, eversible water-absorbing vesicles, and prominent paired terminal cerci.

Collophore

A tubular ventral organ located on the first abdominal segment ($A1$) of springtails (Collembola) used for osmoregulation, fluid absorption, and adhesion.

Furcula

The forked jumping organ located on the fourth abdominal segment ($A4$) of Collembola, consisting of a manubrium, paired dens, and terminal mucros held by the tenaculum.

Order Archaeognatha

Jumping bristletails; primarily wingless ametabolous insects with large contiguous compound eyes, lateral ocelli, long maxillary palps, abdominal styli, and a long medial caudal filament.

Order Zygentoma

Silverfish; dorsoventrally flattened wingless ametabolous insects with widely separated compound eyes, absent ocelli, long cerci, a median caudal filament, and lifelong moulting.

Medial Caudal Filament

A thread-like terminal appendage situated between the cerci on the abdomen of basal insects (e.g., Archaeognatha, Zygentoma, Ephemeroptera) that provides balance and steering.

Paranotal Hypothesis

The hypothesis proposing that insect wings originated de novo as lateral cuticular lobes or bulges on the terga of the thoracic segments.

Dual Origin Hypothesis

The leading hypothesis suggesting insect wings developed through the fusion of ancestral paranotal thoracic tergal flaps and re-expressed appendage/gill gene networks.

Direct Flight

A flight mechanism where wing muscles attach directly to the wing bases (as in Odonata and Ephemeroptera), causing a wingbeat rate directly limited by nerve impulse frequency.

Indirect Flight

A flight mechanism where flight muscles deform the thoracic capsule rather than pulling directly on the wings, enabling exceptionally fast, resonant wingbeat frequencies.

Infraclass Palaeoptera

A lineage of ancient winged insects (Odonata and Ephemeroptera) that cannot fold their wings back flat over the abdomen at rest and possess direct flight mechanics.

Infraclass Neoptera

A monophyletic clade comprising $95\%$ of extant insects whose wings possess flexion lines and reduced venation allowing them to fold back over the abdomen at rest.

Comstock-Needham System

The standardized morphological framework describing homologous insect wing venation using six longitudinal veins: Costa, Subcosta, Radius, Media, Cubitus, and Anal.

Order Meganisoptera

An extinct order of giant griffinflies related to dragonflies that existed $300\text{ Mya}$, reaching wingspans up to $70\,cm$ due to high atmospheric oxygen ($>21\%$) and lack of bird predation.

Order Odonata

The order of dragonflies and damselflies, characterized by huge compound eyes, minute setaceous antennae, direct flight muscles, an aquatic predatory larval stage, and an extensible labial mask.

Nodus

A prominent structural notch and cross-vein along the costal margin of Odonata wings that permits dynamic twisting and flexibility during predatory flight.

Pterostigma

A heavily pigmented, thickened cuticular cell situated near the costal apex of an insect wing that acts as a stabilizing counterbalance to reduce flutter at high speeds.

Mask (Labial Mask)

The prehensile, hinged lower lip (extensible labium) possessed by Odonata nymphs, equipped with moveable apical hooks to capture aquatic prey.

Suborder Anisoptera

Dragonflies; characterized by contiguous compound eyes, broad-based hindwings held out horizontally at rest, robust bodies, and internal rectal gills in larvae.

Suborder Zygoptera

Damselflies; characterized by widely spaced compound eyes, similar fore- and hindwing shapes held folded along the back at rest, slender bodies, and three external caudal gills in larvae.

Subimago

The unique, fully winged but sexually immature penultimate life stage found exclusively in the order Ephemeroptera that moults once more into the reproductive adult (imago).

Order Ephemeroptera

Mayflies; aquatic insects possessing non-functional adult mouthparts, reduced hindwings, abdominal gills in larvae, and a winged subimago stage.

The Polyneoptera

A major clade of Neopteran insects retaining ancestral features including chewing (mandibulate) mouthparts, $9\text{--}11$ abdominal segments, leathery tegmina, broad fan-like hindwings (vannus), and cerci.

Tegmina

Hardened, leathery or parchment-like forewings characteristic of Polyneopterans that serve primarily to cover and protect the delicate membranous hindwings.

Vannus

The enlarged anal fan region of the hindwing in Polyneoptera that folds along multiple radiating flexion lines under the tegmina when at rest.

Order Dermaptera

Earwigs; nocturnal Polyneopterans possessing a dorsoventrally flattened body, short tegmina, and cerci modified into stout, sexually dimorphic pincers used for defense and courtship.

Order Orthoptera

The order containing grasshoppers, crickets, and katydids, recognizable by saltatorial hindlegs with enlarged femora, sound production via stridulation, and auditory tympana.

Stridulation

The production of sound by rubbing specialized cuticular ridges or files on the wings or legs against one another or against the body to attract mates or defend territory.

Tympanum

A membrane-covered auditory chamber used for hearing sound frequencies; located laterally on the first abdominal segment in grasshoppers and on the front tibia in crickets.

Order Blattodea

The order comprising cockroaches and termites, characterized by a hypognathous head covered or supported by an enlarged shield-like pronotum, long filiform antennae, and chewing mouthparts.

Superorder Acercaria

A major Neopteran clade of true bugs and allies characterized by the complete loss of cerci, specialized piercing-sucking (haustellate) mouthparts, and hemimetabolous development.

Rostrum

The beak-like piercing-sucking proboscis of Hemiptera formed by the elongated, grooved labium enclosing needle-like mandibular and maxillary stylets.

Hemelytra

The distinctive forewings of true bugs (Hemiptera) featuring a thickened, leathery basal region and a clear membranous apical tip.

Scutellum

A prominent, rigid triangular plate derived from the mesonotum situated between the wing bases that protects the thorax and transmits flight vibrations.

Family Pentatomidae

Stink bugs; Hemipterans possessing a shield-shaped, dorsoventrally flattened body, a large triangular scutellum, $5$-segmented antennae, and foul defensive metathoracic scent glands.

Evapatorium

A textured, micro-sculptured cuticular area surrounding the metathoracic scent gland openings in stink bugs that promotes rapid vaporization of defensive volatile compounds.

Brochosomes

Microscopic proteinaceous and lipid-rich secretory particles produced in the Malpighian tubules of leafhoppers and spread over their bodies using setae to provide a hydrophobic coating.

Family Cicadellidae

Leafhoppers; laterally flattened, torpedo-shaped Hemipterans featuring rows of spines on their jumping hindlegs and often exhibiting wing dimorphism.

Cornicles

A pair of upright tubular abdominal structures in aphids (Family Aphididae) that secrete defensive droplets and alarm pheromones.

Cauda

A tail-like abdominal projection in aphids positioned below the cornicles used to maneuver and flick away excretory honeydew droplets.

Ametabolous Development

Primitive insect life history lacking distinct metamorphosis; nymphs emerge looking like miniature adults and continue moulting throughout adulthood.

Hemimetabolous Development

Incomplete or gradual metamorphosis where juveniles (nymphs) progressively develop adult features and external wing buds across successive moults without entering a pupal stage.

Holometabolous Development

Complete metamorphosis characterized by distinct, specialized egg, larval, non-feeding pupal, and winged adult stages.

Parasitoid

An insect whose larvae live as parasites inside or on the body of a host insect, systematically consuming it and ultimately causing its death.

Imaginal Discs

Undifferentiated groups of embryonic cells set aside in holometabolous larvae that remain intact through pupal caspase breakdown to form adult structures.

Juvenile Hormone (JH)

A hormone maintaining juvenile characteristics; high levels maintain larval moulting, a decline allows pupation, and its absence triggers the final moult into a winged adult.

Prothoracicotropic Hormone (PTTH)

A brain neuropeptide released in response to physiological (critical body mass) or environmental signals that triggers the prothoracic gland to release ecdysone.

Ecdysone

A steroid hormone secreted by the prothoracic gland in response to PTTH that directly stimulates the epidermis to synthesize a new cuticle and initiate moulting.

Critical Body Mass

The physiological threshold where soft tissues completely fill the cuticular exoskeleton, triggering stretch receptors that stimulate the brain to release PTTH.

Pronymph Theory

The evolutionary hypothesis positing that the holometabolous larval stage represents a precociously hatched pronymphal embryo resulting from early juvenile hormone mutations.

Order Hymenoptera

The holometabolous order containing sawflies, wasps, ants, and bees, recognizable by coupled wings (hamuli), haplodiploid sex determination, and a constricted petiole.

Petiole

The narrow waist found in apocritan Hymenoptera formed by a constriction between the first abdominal segment ($A1$, the propodeum) and the second ($A2$).

Gaster

The enlarged, bulbous posterior abdominal region in Hymenoptera situated behind the constricted petiole.

Hamuli

A row of tiny microscopic hooks on the anterior margin of the hindwing that interlock with the folded margin of the forewing to synchronize wing movement during flight.

Haplodiploidy

A sex-determination system in Hymenoptera where unfertilized haploid eggs develop into males via parthenogenesis and fertilized diploid eggs develop into females.

Family Apidae

Bees; characterized by branched or plumose body setae, an elongated labium adapted for nectar extraction, corbicula on female hind tibiae, and UV-sensitive vision.

Corbicula

The pollen basket of apid bees, formed by a smooth, concave surface bordered by stiff, curved setae located on the exterior surface of the hind tibia.

Waggle Dance

A complex behavioral ritual performed by worker honeybees inside the hive that conveys the exact distance and angular direction of a remote food source.

Royal Jelly

A protein- and nutrient-rich secretion produced by worker nurse bees fed exclusively to selected female larvae to stimulate reproductive development into a queen bee.

Family Formicidae

Ants; a fully eusocial hymenopteran family characterized by geniculate antennae, metapleural glands, one or two petiole nodes, and an infrabuccal sac.

Metapleural Gland

A gland unique to female ants situated on the posterolateral margin of the metathorax that secretes potent antimicrobial substances to protect the nest from infection.

Petiole Node

One or two dorsal scale-like or humped projections on the petiole of ants that increase abdominal flexibility and serve as diagnostic taxonomic identifiers.

Infrabuccal Sac

A specialized pre-oral pocket beneath the mouthparts of adult ants used to filter, store, and compress swallowed solid debris into compact pellets that are spit out.