Lecture 4: insect life cycle Flashcards
do all insects lay eggs?
no, not all. several are viviparous
what is a micropyle?
-small lump on egg, allow sperm into egg, always present
egg shell architecture:
- must be pretty waterproof
- identify species from it
- holes to allow gas exchange
aphids reproduction when food is abundant
-Asexual, females produce females
Botfly reproduction:
parasitic fly needs to get its larva onto a host quickly so it can burrow into the host, so can’t be flicked on, greater chance of infection
when insect first emerges from egg its called
1st instar
whats the difference between 1 instar and say 4th instar?
- constructing exoskeleton, so sequence of instars
- number relates to how many times they’ve emerged from a previous skin
technical term for adult insect
imago (has functional reproductive organs/ fully formed wings)
what happens between each instar
Moult, (another term = Ecdysis)
‘shed skin’ from a moult =
exuvia
Metamorphosis:
transformation from one form to another form i.e. pupa -> imago
does metamorphosis happen in hemimetabolism
YES; the acquisition of wings
mayfly; how many instars?
30+
-tend to find insects which evolved long time ago, they have more instars
in some species females have ___ instars than males
MORE
Ametabolous development:
- only relevant for Apterygote insects
- NO WINGS
- young stages are essentially identical to adults
- in some they continue to moult once reached adulthood
Hemimetabolous development:
- exopterygotes
- infant go through several instars
- infants small versions of adult
- e.g. cockroach, dragonflies, stoneflys, mayflys, true bugs, grasshoppers, crickets
holometabolous development:
- larva, pupa, adult
- insect is digested away in pupa and rebuilt
- endopterygote insects
- e.g. butterfly, scorpion fly, flies, ants, bees, wasps & beetles
different types of post embryonic development:
- holometabolous
- hemimetabolous
- ametabolous
larval types: Oligopod larvae (with developed legs)
- Campodeiform (look like insects)
- Scaraebaeiform
larval types: polypod larvae
also known as eruciform
larval types:
- oligopod
- polypod
- apodous
larval types: apodous
NO LEGS; ‘maggots’
-described by development of head capsule
pupal types:
also has complex variety, linked to almost how recognisably a insect they are
