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Important Concepts of Insect Development

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Title: PowerPoint Presentation Author: Evan Sugden Last modified by: Evan Sugden Created Date: 7/23/2008 4:57:26 PM Document presentation format: On-screen Show – PowerPoint PPT presentation

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Title: Important Concepts of Insect Development


1
Important Concepts of Insect Development Life
Histories
This applies to Hans lecture and the canned
lecture not presented in class but posted, a few
slides of which are shown here for emphasis.
  • Major types of development what is
    metamorphosis?
  • Importance of holometabolism.
  • Special features of holometabolism pupa,
    imaginal discs.
  • Involvement of hormones in development,
    especially holometabolism.
  • The process of molting (various phases including
    the 7 steps of Evans).
  • Implications of molting necessity, advantages,
    disadvantages.
  • Polymorphism what is it? How is it manifested?
    Why is it important?

2
Major types of insect metamorphosis
3
from Gullen Cranston, 2000
Growth and development (molting metamorphosis)
in a chironomid midge, a holometabolous insect.
4
Distribution of imaginal discs in a Drosophila
larva (DIPTERA). Many of the adult features are
preformed and packaged in the larval stage. This
simplifies pupal transition.
from Evans 1984
An example development of wing buds in a
caterpillar larva (LEPIDOPTERA).
from Evans 1984
5
from Evans, 1984
in Poropoea, a chalcidoid parasite of beettle
larvae, HYMENOPTERA
Hypermetamorphosis
in a Rhipiphorid beetle, COLEOPTERA
6
Neurosecretory aspects of the insect brain.
Neurosecretory cell clusters may contain as few
as a single cell each.
from Evans 1984
7
PTTH
Basic hormones, pathways, control of molting in
holometabolous insects.
JH
ecdysone
8
REVIEW basic insect cuticle structure
from Gullen Cranston 2000
9
The seven basic phases of insect molting.
from Evans 1984
10
Polyphenism in aphids. Determined by season,
food quality, crowding, predator pressure.
Mediated by hormones. In many spp., involves
assexual sexual reproductive phase, apterous
and winged phases.
Sunflower aphid. a), b) ovoviviparous,
apterous forms c) sexual alate (lays eggs)
11
Polymorphism is social insects may involve
several axes of differentiation 1) sexual
(male vs. female), 2) reproductive (vs.
non reproductive), 3) worker castes
(grades of morphology behavior).
12
Age-related polyethism in the honey bee, Apis
mellifera. Responsive (to colony environment),
highly structured (by age), but flexible
(contingent on colony needs).
from Winston 1987
13




END


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