Lecture 2: Developmental stages

Question 1

What is metamorphosis

Answer 1

Developmental changes experienced by an insect q

Question 2

What is an instar?

Answer 2

A stage in between moulting

Question 3

What are the three types of metamorphosis

Answer 3

ametabulous
hemimetabulous
holometababulous

Question 4

Give some differences between hemimetabulous and holometabulus metamorphosis

Answer 4

Hemi- Insects increase in size, wings develop externally hence the name exopterygota
Holo-Larval forms are morphologically different from the adult form, wings develop internally (in the pupa) hence endopterygota

Question 5

What is the purpose of changes in lifestyle of larval versus adult stages in the Endopterygotan life cycle

Answer 5

Larvae- Main concern is to harvest resources and sometimes for dispersal, food availability is the key element during this stage
Pupa- Main concern is metamorphosis, from the larval stage to the imago, safety is the key element during this stage
Adult- Main concern is reproduction

Question 6

Name and describe different types of larvae

Answer 6

Eruciform- Caterpillar like
- Well developed head and mouth parts, three pairs of jointed thoracic legs. Prolegs on the abdomen
- Active
Scarabaeform- Grub like
- Well developed head capsule, three pairs of jointed thoracic legs and no abdominal legs
- Do not hunt for food
Vermiform- Maggot like
-Fleshy, no appendages, head capsule reduced
Elateriform- Wire worm like
-well developed head, tiny thoracic legs, no abdominal legs, wire shaped
Campodeiform- Centipede like
- prothagnacious moth parts, well developed head

Question 7

What is hypermetaorphosis

Answer 7

Changes in form from one instar to another within the same species

Question 8

Explain the types of pupae

Answer 8

Obtect- pupa covered in a hard chitinous coat, insects appendages are glued to the body
Exarate- appendages visible, not glued to the body, pupa is in a safe place eg in a web of silk
Coarcate- covered by a puparium