Some insects produce living young ones instead of laying eggs or in other words give birth to the larvae and the process is called viviparity Though it is not a true viviparity as occur in mammals because it lacks a typical ID: 935496
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Slide1
V
IVIPARITY
Slide2Viviparity
Some
insects produce living young ones instead of laying eggs or in other words; give birth to the larvae and the process is called
viviparity
.
Though
it is not a
true
viviparity
as occur in mammals because it lacks a typical
placenta.
Slide3Hagan (1951)
classified
viviparity
into 4 types
:
1.
Ovo
-
viviparity
.
2.
Adenotrophic
viviparity
3.
Haemocoelous
viviparity
4.
Pseudoplacental
viviparity
Slide4Ovo
-
viviparity
:
The fertilized eggs of
ovo
- viviparous insects contain yolk which is required for the development of embryo and such eggs are incubated inside the mother.
The developing embryo does not absorbs any nutrient from the mother and the mother gives birth to hatched larvae or sometimes the fully developed eggs are laid which immediately hatched out (no incubation).
It is found in
Thysanoptera
,
Blattidae
,
Mucidae
,
Tachinidae
and in
few coleopterans.
Slide5Adenotrophic
viviparity
The fertilized eggs contain yolk but are thinly
chorionated
.
The fully developed larva emerge from the yolk which is poorly developed and therefore remains inside the uterus of the mother.
The larva feeds orally on the secretions produced by the
hypotrophied
uterine glands of the mother.
By taking those secretions, larva grows further and
moults
twice inside the uterus which later deposited outside the mother’s body in the form of the fully grown larva which is ready to pupate.
Slide6E.g
.,
Glossinidae
and
Hippobossidae
;
the oviduct of the mother swells up and called the uterus
.
The
accessory glands are well developed which are called the
milk glands
.
Only
a single egg develop inside the uterus receiving the nutrient from mother and deposited outside the body prior to pupation.
Slide7Female reproductive system of
Glossina
Slide8Milk Gland of
Glossina
Slide9Haemocoelous
viviparity
It is a highly specialized type of
viviparity
which is found in
Strepsipterans
and
Ceicidomyidae
(gall midges).
The ovaries disperse into the
haemocoel
surrounded by
haemolymph
.
The fertilized eggs are without yolk and
chorion
but surrounded by a trophic membranes.
Slide10The
nutrients from
haemolymph
pass through trophic membranes by osmosis
.
After
the complete development; larva escape through brood canal in
Strepsiptera
.
In
gall midges,
larva feeds upon the maternal tissues and escape through the skin.
Slide11Pseudoplacental
viviparity
Very much
close to the mammalian type of
viviparity
.
Fertilized eggs do not contain yolk; the embryo
developes
within the genital tract of mother with a formation of special placenta like tissues associated with the embryo.
The nutrients transfer through these nutrient tissues from mother to embryo.
No oral feeding occurs.
It occurs in
Hemiptera
,
Dermaptera
,
Psocoptera
, etc.