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International Journal of
Entomology Research
ARCHIVES
VOL. 7, ISSUE 4 (2022)
Egg structure and fertilization in six libellulid dragonflies (Insecta: Odonata)
Authors
Payal Verma
Abstract
The egg of the exophytic dragonflies i.e., Acisoma panorpoides, Crocothemis servilia, Neurothemis tullia, Orthetrum sabina and Rhyothemis variegata and Pantala flavescens exhibit oval, subspherical or spindle shape. Whereas, egg of epiphytic Brachythemis contaminata is cylindrical in shape. The egg hatch in 7-15 days and turn dark within a few hours in water. The chorion is distinctly divided into an outer exochorion and an inner endochorion. In water, the exochorion expands into a transparent, thick, sticky jelly-like structure. A well-defined nipple shaped micropylar apparatus is located at the anterior end of the egg. It is composed of a small basal sperm storage chamber (atrium) and a median projecting stalk which possesses a pair of subterminal orifices. For fertilization the mature eggs travels down the oviduct and enter the cuticular vagina. The pair of cuticular membranes present on the floor of the vagina slides the egg in the vagina where it is held by the lateral vaginal plates and the micropylar apparatus comes to lie under the fertilization pore. The campaniform sensillae of lateral vaginal plate transmit an impulse to the last abdominal ganglion which decodes and stimulates the muscles of bursa copulatrix and spermatheca to contract. This releases sperm material which reaches the tubular fertilization pore passing through the bursa communis. The sperm rushes down the passage of the fertilization pore and slithers inside the micropylar orifice located on either side of the micropylar stalk to reach the micropylar atrium for fertilization.
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Pages:86-91
How to cite this article:
Payal Verma "Egg structure and fertilization in six libellulid dragonflies (Insecta: Odonata)". International Journal of Entomology Research, Vol 7, Issue 4, 2022, Pages 86-91
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