Intro to entomology Flashcards
how long have insects been in existence
over 350 million years with around 1 million known species but likely over 10 million
what are the secrets to insects success
1) small size
- use many micro habitats
- reduced resources needed
- effect of gravity is less
- predator avoidance
- low body size: body mass means higher proportional body mass
2) Fast reproduction
- high rate of evolution to adapt to new conditions
- high fedundity producing lots of eggs
- high fertility- most eggs hatch
- fast life cycle= 2-3 weeks
how are insects important
1) ecosystem services
- plant propagation, pollination
- nutrient cycling, decomposition
- maintenance of plant community structure (grazers)
- maintenance of animal community structure (predators, parasites, vectors)
2) keystone species
- control potential dominants e.g. parasitic wasps
- resource providers e.g. symbiotic bacteria in termites for cellulose breakdown
- mutualists e.g. plant-pollinator co evolution
- ecosystem engineers e.g. termites an and ants
3) economic importance
- value of pollinators and dung beetles
- cause £ billions damage to crops, stored food/ animals
- 20% crops grown for humans to eat are eaten by insects
- control spread of disease 1/6 ppl currently infected by insect borne disease
outline the paper by the royal entomology society = Grand challenges in entomology
outline the sub phylum of arthropoda known as hexapoda
name for six legs
more species rich than all other life forms combined
live in almost every terrestrial habitat and some freshwater
- split into Insecta and entognatha
what are the three orders which come under Entognatha within the hexapoda
1) collembola
2) Protura
3) Diplura
outline the class entognatha under the subphylum Hexapoda
- Apterous = primitivley lacking wings
- entognathous mouth parts = retract within the head
- each antennal segment is muscled
- only collembola have eyes
what is the class ‘insecta’ under the subphylum ‘hexapoda’ split into
1) Apterygota
2) pterygota
what are the three groups insecta are divided into depending on development
1) Ametabola = without metamorphosis
- egg –> grow bigger
2) Hemimetabola = half metamorphosis
- egg –>nymph–>adult
3) Holometabola = whole metamorphosis
- egg –> larvae –> adult
what is pterygota under the class insecta split into
1) paleoptera
2) Neoptera ( then split into exo/endopterygota)
outline an ametabolous life cycle
e.g. silver fish
primativley wingless orders develop into adults by moulting periodically growing in size
outline a hemimetabolous lifecycle
e.g. dragon fly
winged insects change gradually by incomplete metamorphosis
outline a holometabolous lifecycle
e.g. butterfly
involves a pupal stage and is termed complete metamorphosis
outline the subclass apterygota
- formerly included other primitively wingless insects now in entognatha
- restricted to two orders = Archaeognatha and zygentoma
= superficial similar but not closley related due to differences in mouthparts
outline the order Archaeognatha aka bristletails under the subclass apterygota
primitivley wingless
active and cylindrical around 18mm
long flagellate antennae
most of body covered in flat scales
well developed eye and 3 ocelli
lives in leaflitter/under stones/ seashore feeding on alage/ lichens
courtship rituals
outline the order Zygentoma aka silver fish under the subclass apterygota
primitivley wingless
sacvengers
fast runners but do not jump
less cylindrical tapering at rear
dorsoventrally flattened
covering of scales = makes them look shiny
eyes reduced/absent
outline the subclass pterygota
ancestors of winged insects that evolved in carboniferous period
- some lost wings later
why did some ptergytoa lose their wings
specialisation
habitat stability
what are the two infraclasses of the subclass pterygota
1) paleoptera - old wing
2) neoptera - new wing
outline the infraclass paleoptera
characterised by position of wings at rest
1) unable to fold over abdomen
- ephemeroptera (mayfly) = over head
- odonata- held outstreched (dragon fly) or above abdomen (damael fly)
= hemimetabolous
outline characteristics of mayflies aka ephemeroptera
two seperate flying stages
1) sexually immature subimago hatches from nymphal stage and flies from water
2) sexualy mater imago
= sexually dimorphic
adults shortlived and non-feeding
larvae aquatic scrapers and keystone species
outline characteristics of odonata aka dragonflies and damsel flies
large compound eyes, short antenna
2 pairs of wings
bright colours= females more drab
aquatic nymphs
associated with water
aquatic and terrestrial predators
outline neoptera
split into two groups
1) exopterygota
- young look like adults but externally developing wings
- immature to adult without pupal stage
- nymphs develop gradually into adults before moulting
2) endopterygota
- develop wings inside body
- distinctive larval, pupal and adult stages
- radical metamorphosis with larval and adult stages differing in structure and behaviour
