References

Alexander, R. D. 1964. The evolution of mating behaviour in arthropods. Royal Entomol. Soc., Symp. 2: 78-94. Blum, M. S., and N. A. Blum. 1979. Sexual selection and reproductive competition in insects. Academic, New York. Davey, K. G. 1965. Reproduction in the insects.

Freeman, San Francisco. Eberhard, W. G. 1985. Sexual selection and animal genitalia. Harvard Univ. Press, Cambridge.

Englemann, F. 1970. The physiology of insect reproduction. Pergamon, Oxford. Thornhill, R., and J. Alcock. 1983. The evolution of insect mating systems. Harvard Univ. Press, Cambridge.

Fertilization

The sperm cells produced by the testes are introduced internally into the female in most forms, that is, fertilization is internal. They may be first kept in storage in diverticulae of the common oviduct, however, and released to fuse with the eggs only as they pass, the female thus controlling the time of fertilization.

Introduction of sperm is not always directly via the gonopore. Secondary genitalia are developed most notably in Odo-

nata and spiders. The former transfer the sperm from the gonopore to the accessory copulatory organs on the venter of the third abdominal segment; male spiders use syringes in the bulbous apex of the pedi-palps for this purpose. Sperm is carried in a liquid medium, or more commonly, compressed into packets (spermatophores) that may be inserted into, or formed, in the common oviduct or its outpocketings (spermathecae), or are placed on the substratum to be picked up by the female.

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