2. Different types of reproduction
1.Oviparity
2.Viviparity
3.Parthenogenesis
4.Polyembroyny
5.Paedogenesis
.
3. 1.Oviparity
Most of female insects are oviparous.
Eggs are fertilized within the body of the female and
deposited outside.
Embryonic development occurs after oviposition by utilizing
the yolk of the egg.
These eggs laying insect are oviparous.
Eg.Headlouse, butterflies and moths.
4. Viviparity
unlike oviparous,initiation of egg development takes
place within the mother.
The lifecycle is shortened by retention of eggs and
even developing young ones within the mother.
Thus the insects instead of laying eggs,produce
directly young ones (nymphs or larvae).
There are 4 main types of viviparity
5. Ovo-viviparity
Fertilized eggs containing yolk are retained in the
reproductive tract of the female till the embryo
reaches the advanced stage of development and so
hatching of egg occurs just prior to or soon after
oviposition.
Eg.Thysonoptera,some cockroaches,few beetles.
6. Pseudo- placentral viviparity
This occurs when a yolk-deficient egg develop in the
genital tract of the female.
The mother provides a special placenta-like tissue,
through which nutrients are transferred to developing
embryos.
There is no oral feeding and larvae are laid upon
hatching.
Eg.Aphids,some earwigs, psocids and polytenoid bugs.
7. Haemocoelous viviparity
This involves embroys developing free in the female’s
haemolymph with nutrients taken up by osmosis.
This form of internal parasitism occurs only in
Strepsiptera and some gall midges.
8. Adenotrophic viviparity
This occurs when a poorly developed larva
hatches and feeds orally from accessory(milk) gland
secretion within the uterus of the mother’s
reproductive system.
The full-grown larva is deposited and pupates
immediately.
Eg.tsetse flies.louse or wallaby flies
9. Parthenogenesis
• It is the development of the egg without fertilization.
Different types of parthenogenesis are as follows
Based on occurrence
• Facultative-eg bees
• Obligatory or constant-eg.Stick insect
• Cyclic or Sporadic –alternation of gamic and agamic
population,Aphids
Based on sex produced
• Arrhenotoky-Produce male.eg.bee
• Thelytoky-Produce female eg.aphids
• Amphitoky or deuterotoky-Produce both male and
female.eg.cynipid wasp.
10. Based on meiosis
Apomictic-no meiosis occurs
Automictic-meiosis occurs,but diploidy is
maintained.
11. Polyembryony
Asexual reproduction involves the
Production of two or more embryos from one
egg by subdivision.
Mostly observed in parasitic insects
eg.platygaster.
Nutrition for a large number of developing
embryos cannot be supplied by the original
egg and is acquired from the host’s
haemolymph through a specialised
enveloping membrane called trophamnion.
12. Paedogenesis
The mode of reproductive by the immature
forms before attaining the adult stage.The type of
reproduction is parthenogenesis.
Larval paedogenesis-eg.gall midges.
Pupal paedogenesis-eg.Miaster sp.
