Entomology

Hexapoda= insecta + entognatha.

What are the three orders of entognatha?

Collembola, proteus and diplura

What are the features of entognatha?

• Apterous (lack wings)

• Entognathous mouthparts (retract within head)

• Muscled antennas segments

What three groups are insecta divided into depending on development?

Ametabola, heminetabola, holometabola

Insecta are split into groups dependant on wing development. What are these groups?

Insecta is split into apterygota and pterygota.

Pterygota is split into paleoptera and neoptera.

• Neoptera is split into exopterygota and endopterygota.

What is the ametabolous lifestyle?

Develop by moulting periodically

What is the hemimetabolous lifecycle?

Winged insects change gradually by incomplete metamorphosis

What is the holometabolous lifecycle?

Involves a pupal stage and is termed complete metamorphosis

What are archaeognatha bristle tails?

• Wingless

• Active, cylindrical insects

• Flat scaled bodies

• Found in leaf litter, under stones and on seashores

What are zygentoma (silverfish)?

• Wingless

• Dorsoventrally flattened

• Shiny appearance

What are paleoptera?

• Characterised by position of the wings at rest

• Mayflies, dragonflies, damselflies

What is the super order exopterygota?

• Young, resemble adults but still externally developing wings

• Require moulting to develop to adult

What is the super order endopterygota?

• Develop wings inside body

• Distinct larval, pupal and adult stages

What are Plecoptera?

• Stoneflies

• Sensitive to organic pollution

• Wings of most have veins that form a double ladder

• Weak flying

What are blattodea?

• Cockroaches and termites

• Tegmina (toughened front wings)

• Ecosystem engineers

• 3 native cockroaches to the UK

What are the mantodea?

• Mantids

• Modified front legs for prey capture

• Tropical and sub tropical environments

What are notoptera?

• Ice crawlers and heelwalkers

• Includes mantophasmatidae and grylloblattidae

• Found in high elevations

What are dermaptera?

• Earwigs

• Thickened forewings and flattened abdomen

• Females show parental care

• Have cerci for protection

What are Orthoptera?

• Grasshoppers, crickets and bush crickets

• Long hind legs for jumping

• Wings form stridulatory organs

• Songs can be used for Identification

• Serious crop pests (eg: locust)

What is the scientific group of grasshoppers?

Caelifera

What is the scientific group name for crickets?

Ensifera

What are phasmatodea?

• Stick and leaf insects

• Slow moving, confounded to vegetation

What are embiotera?

• Webspinners

• Swollen first tarsal segment contains silk glands

• Females wingless

What are zoraptera?

• Angel insects

• Small termite like

• Rare

what are psocodea?

• lice

• Small and cryptic

• Détritivores

What are phthiraptera?

• Parasitic lice

• Secondarily wingless

• No eyes

• Well developed claws to cling onto host

• Modified mouthparts for chewing or piercing

What are Hemiptera?

• True bugs

• Heteroptera- aquatic bugs

• Auchenorrhyncha- cicadas, leafhoppers, tree hoppers

• Strrnorrhyncha- aphids and scale insects

• Coleorrhyncha- only contains the peloridiidae family

What are Thysanoptera?

• Thrips

• 1-3mm

• Slender with well developed eyes

• Ciliated wings

• Well developed mouthparts

What are megaloptera?

• Alder flies

• Freshwater predators that possess strong jaws

• Abdomen with fine tactile filaments and gills

What are Neuroptera?

• Lacewings, antlions and mantidflies

• Larvae are specialised predators adapted for piercing and sucking

• 69 species in 6 families in the uk

What are Coleoptera?

• Beetles

• Hard elytra cover most of their body

• Larvae is the main feeding stage

• Identification of larvae difficult as morphology varies

What are strepsiptera?

• stylops

• Sexually dimorphic

• Endoparasites of insects such as bees, wasps, silverfish and cockroaches

What are raphidoptera?

• Snake flies

• Strong and unspecialised mouthparts

• Three pairs of true legs but no prolegs

• Adhesive organ on abdomen to fasten themselves to vertical surfaces

What are Siphonaptera?

• Fleas

• Secondary wingless

• Long legs adapted for jumping

What are Diptera?

• True flies

• One pair of functional wings

• Large compound eyes and 3 ocelli

• Head not distinguishable from body

What are trichoptera?

• Caddisflies

• Nocturnal

• Two pairs of hairy/scaly wings

• Aquatic larvae indicate water quality

What are Lepidoptera?

• Butterflies and moths

• Wings with flattened scales

• Mouthparts adapted into tubular proboscis

What are Hymenoptera?

• Bees, wasps, sawflies and ants

• Wings linked by hamuli

• Females are diploid, males are haploid

• Complex social behaviour

• Most are parasitic

what are lamellate antennae found on?

scarab beetles

what are setaceous antennae found on?

cockroaches and caddisflies

what are antennae used for?

• Detecting sound, wind speed and humidity. Also to attract mates.

• They are made up of a scape, pedicel and flagellum

what 4 components are in insect mouthparts?

1. Labrum acts as upper lip

2. Paired mandibles for chewing and cutting food

3. Paired maxillae for handling food

4. Labium acts as lower lip

what are the 6 sections of an insect body?

1. head

2. prosoma

3. thorax

4. mesosoma

5. abdomen

6. metasoma

what are the 6 leg adaptions?

1. Cursorial- fast running

2. Fossorial- digging

3. Saltatorial- jumping

4. Natatorial- swimming

5. Raptorial- capturing prey

6. corbiculae- collecting pollen

what are the functions of insect wings?

1. communication

2. camouflage

3. thermoregulation

4. protection

5. balance

6. flight

describe direct muscle attachment

• found in paleoptera and dragonflies

• muscles attached to wing bases

describe indirect muscle attachment

• found in neoptera and butterflies

• muscles attached to thorax

what is synchronous innervation?

1:1 relationship between nerve impulses and contraction

• found in all paleoptera

what is asynchronous innervation?

multiple contractions per nerve impulse

• found in some advanced neoptera

what are the 6 functions of the cuticle?

1. mechanical protection

2. prevents desiccation

3. protective barrier

4. location of colour and pattern

5. for muscle attachment

6. lines the external body surface, trachaea, reproductive system

What is the procuticle?

secreted protein and chitin.

• outer exocuticle = sclerotised

• inner endocuticle = undifferentiated

what is the epicuticle?

Has no chitin, made up of lipids

• outer epicuticle = non elastic lipids and protein

• inner epicuticle = tanned lipoproteins

what are the 5 types of procuticle in different species or life stages?

• undifferentiated = soft and reversible

• rigid = tanned and irreversible

• membranous = flexible and untanned

• elastic = includes resilin

• calcified = flexible and untanned

what is ecdysis and its functions?

Ecdysis is the process of molting old cuticle layers and the formation of a new one.

Function:

1. allow insect to grow

2. replace mouthparts

3. replace trachea lining

4. restore waterproofing

5. shed pathogens

what are some cold adaptions insects have?

• Northern insects produce cryoprotectants, polyols, sugars and antifreeze proteins. Then remove ice nucleators and lower supercooling point. High mortality between -20c to -40c.

• Southern insects can survive being frozen. Produce cryoprotectants, polyols, sugars and antifreeze proteins. Then ice nucleators initiate extracellular freezing at -5 to -10c.

what are some hot adaptions insects have?

• burrowing behaviour and long legs

• hot temperatures denature proteins

what are some arid adaptions insects have?

• close spiracles and lower metabolic rate to decrease water loss

• Uric acid precipitation allows reabsorption of water

what are the three classes of mechanoreceptors?

cuticular, sub-cuticular and internal stretch/tension receptors

what are cuticular mechanoreceptors?

Exteroception:

• tactile hairs

• air movement detectors

• gravitational orientation

• pressure receivers

Proprioception

• hair or campaniform sensilla detect movement of body parts in relation to each other

what are sub-cuticular mechanoreceptors used for?

• hearing

• wind and gravity sensing in antennae

what are internal stretch/ tension receptors used for?

• control wing and leg movements

• monitor abdomen during feeding

• monitor movement of food along gut

• monitor oviposition rate

what senses olfactory sources?

• antennae

• maxillary and labial palps

• genitalia

what senses contact chemosensory sources (taste)?

• mouthparts

• legs and antennae

• ovipositor

what are the three allelochemicals?

1. allomones- benefit emitter

2. Kairomones- benefit receiver

3. synomones- benefit emitter and receiver

What is the first line of defence for an insect?

• Crypsis

• Means: visual defence (homochromy, disruptive colouration, countershading)

What are the three types of mimicry?

1. Mimesis: look like an inedible object

2. Batesian: looks harmless is toxic

3. Mullerian: looks toxic and is toxic

What is aposematism?

Warning colours of toxic species

What insects leak chemical defences from their limbs?

• Fireflies leak lucibufagin

• Coleoptera leak cantharidin

What do ants eject as a defence mechanism?

Formic acid

What are PAMPs and PRRs?

PAMPs: pathogen associated molecular patterns

PRRs: pattern recognition receptors

What triggers immune responses in insects?

• The binding of PAMPs by PRRs.

• they work together to bind wounds and invasive pathogens

What is melanisation?

• Important in wound healing, tanning of cuticle and immunity

• Reactive oxygen and nitrogen intermediates made

Why might insect species go extinct?

• pollution

• Habitat loss

• Invasive species

• Climate change

• Over-exploitation

• Co-extinction

Why conserve insect species?

• they are keystone species and bio indicators

• They have economic significance (pest control, pollination)

• They interact with the food web

How does lighting affect insects?

• affects oviposition, navigation, mate attraction, development and circadian patterns

• LED lights are more impactful

what orders of insects are herbivores?

• orthoptera

• phasmatodea

• lepidoptera

• coleoptera

• thysanoptera

• hemiptera

• psocodea

• hymenoptera

• diptera

what are the three categories of herbivores?

1. free living chewers

2. concealed chewers

3. free living sap feeders

What is plant nutrition like and how do insects counter defend it?

• Plants are nutritionally inadequate (limited N and P) creating imbalances in growth

• Insects have increased feeding rates, selection of N rich sites, selective uptake of N, excretion of excess C and obtain nutrients from non-plant sources.

What are plant physical defences like and how do insects counter defend it?

• hardness from cellulose + silica, trichomes alter insect movement and surface waxes defend from pathogen invasion

• Insects have increased head size in chewers, specialised tarsal claws to get past trichomes and tarsal modifications for waxy leaf surfaces

What are plant allelochemical defenses like and how do insects counter defend it?

• Plants have qualitative chemicals or toxins that interfere with metabolism and prevent feeding

• Insects use detoxifying enzymes, excrete nitrogenous waste and sequestration as non-toxin form in haemolymph

what are comminutors?

Comminutors are insects that mechanically break down plant material through chewing, contributing to the breakdown and digestion of tough plant tissues.

what are xylophages?

organisms that feed on wood, primarily fungi and insects like termites

what are coprophages?

organisms that feed on feces, helping with nutrient recycling in ecosystems.

what are necrophages?

organisms that feed on dead and decaying organic matter, playing a crucial role in decomposition and nutrient cycling.

what might insects have mutalisms for?

• gain access to new resource

• transport in exchange for food

• protection in exchange for food

describe entomophily (insect pollination)

• linked to co-evolution of flowering plants (colour and fragrance)

• Pollinators: diptera, lepidoptera, hymenoptera, coleoptera

describe insect fungal dispersal

• leaf cutter ants create gardens of fungus fed by collected leaf pieces

• cultivate fungus for food

• contributes to nutrient cycling

what are parasitoids?

specialist parasites that spend larval stage in host eventually killing the host

what are pest control ecosystem services?

• reduction of pest populations by natural predators (biological control agents)

• 3 types: conservation, classical, augmentation

how many insects are herbivores?

more than 50%

how many of Britain’s insects are parasites?

70%