Lecture 4: insect life cycle

Question 1

do all insects lay eggs?

Answer 1

no, not all. several are viviparous

Question 2

what is a micropyle?

Answer 2

-small lump on egg, allow sperm into egg, always present

Question 3

egg shell architecture:

Answer 3

• must be pretty waterproof
• identify species from it
• holes to allow gas exchange

Question 4

aphids reproduction when food is abundant

Answer 4

-Asexual, females produce females

Question 5

Botfly reproduction:

Answer 5

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

Question 6

when insect first emerges from egg its called

Answer 6

1st instar

Question 7

whats the difference between 1 instar and say 4th instar?

Answer 7

• constructing exoskeleton, so sequence of instars

- number relates to how many times they’ve emerged from a previous skin

Question 8

technical term for adult insect

Answer 8

imago (has functional reproductive organs/ fully formed wings)

Question 9

what happens between each instar

Answer 9

Moult, (another term = Ecdysis)

Question 10

‘shed skin’ from a moult =

Answer 10

exuvia

Question 11

Metamorphosis:

Answer 11

transformation from one form to another form i.e. pupa -> imago

Question 12

does metamorphosis happen in hemimetabolism

Answer 12

YES; the acquisition of wings

Question 13

mayfly; how many instars?

Answer 13

30+

-tend to find insects which evolved long time ago, they have more instars

Question 14

in some species females have ___ instars than males

Answer 14

MORE

Question 15

Ametabolous development:

Answer 15

• only relevant for Apterygote insects
• NO WINGS
• young stages are essentially identical to adults
• in some they continue to moult once reached adulthood

Question 16

Hemimetabolous development:

Answer 16

• exopterygotes
• infant go through several instars
• infants small versions of adult
• e.g. cockroach, dragonflies, stoneflys, mayflys, true bugs, grasshoppers, crickets

Question 17

holometabolous development:

Answer 17

• larva, pupa, adult
• insect is digested away in pupa and rebuilt
• endopterygote insects
• e.g. butterfly, scorpion fly, flies, ants, bees, wasps & beetles

Question 18

different types of post embryonic development:

Answer 18

• holometabolous
• hemimetabolous
• ametabolous

Question 19

larval types: Oligopod larvae (with developed legs)

Answer 19

• Campodeiform (look like insects)

- Scaraebaeiform

Question 20

larval types: polypod larvae

Answer 20

also known as eruciform

Question 21

larval types:

Answer 21

• oligopod
• polypod
• apodous

Question 22

larval types: apodous

Answer 22

NO LEGS; ‘maggots’

-described by development of head capsule

Question 23

pupal types:

Answer 23

also has complex variety, linked to almost how recognisably a insect they are