Insects - Biodiversity
What are arthropods
These are the insects in the anthropod group and were the last group to break off from the common anscetor due to having 6 thoriac legs
What are hexapoda
The insects fall under the hexapoda group
They have a mouthpart that has mandibles
There are 3 pairs of legs so 6 overall
The body consist of 3 tagmate, the head, thorax anf the abdomen
The appendages are uriamous so are single branched
They have compound eyes and have a tracheal system for gas exchange
What are the 2 classes of hexapoda
There are Entognatha that have retractable mouthpart, are blind or compound eyes and are wingless
Insecta are the most abundant species on earth
Why are insects so diverse on earth
There are 30-80 million species so half the globes species diversity
They are small sized so have more niches in a given environment
They have highly organsied sensory and motor neurone system
There is a short generatio time so faster evolutionary change
They have coevolutionary environment with plants and pollinators
Larvae undego metamorphosis to form winged adults
How do insects undergo gas exchange
Undergo gas exchange by respiration through trachea in their exoskeleton
This means their is a limit on body sieze and o2 transport is less efficient as body size increases and body movement force the CO2 out the body
There are branched airways in the trachea and branch to spiracles and trachioles
This has allowed insects to colonise the land
Why are insect ecologically important
They recycle nutrients and break down dead material
They are plant pollinators and disperse the seeds
Maintain plant community composition by grazing
They are food for other animals and are animal parsites for direct predation of disease vectors
What is endosymbionts
Insects fill many niches in the food web due to a variable diet and digestive system so fill many niche and maintain the water balance
What is the hexapod variable diet
Phloem feeders have to much sugar and water in their diet due to suck from plants phloem
They have malpighian tubes that remove the water and sugar from the phloem, and this is then excreted as honeydew
Desert insects dont have enough water and also have malpighian tubes that are tightly bound to the rectum to extract as much water as possible before excretion
Where did insect wings evolve from
They may have come from lobes on the thorax and or the gills when they conquered the land
There is evidnece for gene expression sites
How do insects fly
Some insects like dragon flies and cockroaches have direct flight muscles where the muscle is directly attached to the wing
Some other in fact most others have indirect muscles, which is where they are attched to the thorax and they are then pivoted to allow them to move the wings
There are 4 types of metamorphosis patterns in insects
Ametoboly - Development to adulthood with little body change excetp sexual maturation and happens in wingless primitive insects
Paurometaboly - Gradual change in body form with external wing bud getting larger at each moult happens in Nymphs and mayflies and dragon flies
Hemimetaboly - Gradual change in body form with external wings buds getting larger at each moult
Holometaboly - Drastic change from wingless larvae to winged adult - happens in most insects
What are the major hexapod groups
Thysanura
Palaeoptera
Odonata
Ephemeroptera
Neoptera
Entognatha
What are the Paleoptera
These cannot flex their wings
Include Mayflies, Dragon flies, Damselflies
They are all hemimetabolous
They can be Voracious aquatic predators so in both in water and in the air
What are Thysanura
These are wingless ametabolous primitive insect such as silverfish
What are coleoptera
These are all the Beetles that make up 40% of all insects
They have modified forewings as rigid elyra that civer the hindwing when resting
They are holometabolous so have a larave,pupal and adult stage
They have opposible mandibles and are heavily sclerotized/armoured
Legs often have claws and adhesive structures
What are Lepidoptera
These are Butterflies and moths and all have a liquid diet due to long proboscis
They have a multisegmentted antennae that is clubbed in butterflies and tappered in moths
Moths are nocturnal unlike butterflies
They are holometabolous due to are catipillars when young when young then develop wings during metamorphosis
They have batesian symmetry so are polymorphic so can mimic unplatable model species
What are Hymenoptera
These are sawflies, Wasps ants and Bees
They have mandible mouthparts for sucking and chewing
They are multisegmented anntenae that are long and helf forward
Wings have simple venation and both are coupled by hooks
3 segmented thorax and have a waist called the petiole abdomen
They are homometabolous so larvae lack legs and mandibles
What are Diptera
These are flies, mosquitoes and midges
They are a mimic of Hymenoptera class
Only 1 pair of wings
What are Hemiptera
These are true bugs that all have sucking mouthpart and needle lile stylets
They are all disease vectors
They are paurometabolis so have immature nymphs when young that resemble the adults
They are divided to 2 groups:
Homoptera and Heteroptera that are different due to wing morhpholgy
What are Orthriptera
These are Locusts, Crickets and Grasshoppers
They are usually winged with fore wings behind leathery tegmina and hind are broad at rest and pleated
They have prootum curved over the Pleura
Hind legs are enlarged for jumping
They are Paurometabolous
They have stridulation so file and scraper to make their noise with it being enhnaced by the tegmina
What are Trichoptera
These are caddisflies that have long multisegmented antennae
They have hairy wings that lack discal cells
They are holometabolous
Live in the pupal state and their presence is used to indicate water quality
How do Hymenoptera sexaully reproduce
Females are diploid and males are haploid so this mena they are more related to sister than offspring
What are 3 true sociality traits
Coorperation of individuals other than parent of caring for the young
Overrlap of 2 generations that can contribute to colony labour
Reproductive division of labour with most of the sterile worker caste working on behalf of individuals that are in reproduction
Honey Bees eusociality
There is resource communication, by waggle dancing for directiion,distance and food quality
Eusociality in Warfare and slavery
Cuckoo wasps lay eggs in another wasp nest where they can eat host eggs and larvae to grow
Cuckok bumblebees invade other bees nest asnd kill the queen and lay eggs in collected pollen
Polyergus ants cant take care of young on their own or even feed them so the workers raid formica ants nest and steal the pupar that then hatch and work for the polygerus colony instead
Eusociality in agriculture
Animal domestication and the anst carry aphids to new pastures and clip the aphids wings when they mature
Ants drink the honeydew
Leafcutter ants bring leaves to their nest so fungus can grow on it and then the ants can eat the fungus