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Adults of Dysdercus koenigii remain in continuous copula for up to 72h. The adaptive significance of prolonged copulation in the reproductive bioactivities of D. koenigii was investigated by a series of interrupted mating experiments. The adults were allowed to mate for a specified duration, after which mating was forcibly terminated. The study indicated that insemination in the female takes place during the first day of mating. This was reflected by the observation that 24h mated females laid fertile eggs. Prolonged mating modifies the female’s reproductive behaviour. The duration of mating had a profound effect on the onset of oviposition as well as the total number of eggs and egg batches laid by a female during her lifetime. Female fertility was also correlated with the duration of mating. Therefore, a female mated for 24h laid fewer fertile eggs in comparison to females mated for 48h or 72h. Hatching success decreased significantly in the egg batches laid by a female during the latter part of her life. A mated female exhibited rhythmic ovipositional behaviour. Our results indicated that the rhythmicity of the oviposition changed as a consequence of the different duration of mating. For instance, in females mated for 24h, there was a change in the number of eggs laid and in the rhythmicity of ovipositional peaks. Further, the rate of oocyte growth appeared to be enhanced by mating. This was evidenced by the shorter inter-oviposition period in the case of females mated for a longer period. It is suggested that throughout mating, females acquire additional sperm and non-gametic resources, such as male accessory gland secretions, which govern their reproductive behaviour and physiology.
The ovaries of Dysdercus koenigii are consisted of meroistic telotrophic ovarioles. Each ovariole can be differentiated into tropharium and vitellarium. The tropharium contains stem line oogonia, newly formed oocytes, trophocytes, prefollicular cells and follicular cells. The vitellarium possesses 10-12 developing oocytes. The developing oocytes are connected to the trophocytes, present in the tropharium, by nutritive cords. During premating period, the ovarioles change, resulting in increase the number of oocytes in the vitellarium. The developing oocytes in the initial stage of development are surrounded by columnar follicular cells, which are subsequently changed to cuboidal and squamous cells in a sequence. The process of vitellogenesis was initiated after 48 h of adult development with the appearance of perioocytic space. There was deposition of yolk material at the periphery of oocytes in the ovarioles of 72 h old females. The further development of oocytes and vitellogenesis remained suspended up to 12-14 days in the virgin females. On the other hand, mating stimulates the oocyte development and process of vitellogenesis. There were distinct morphometric and histological changes in the ovarioles as a consequence of mating; dimensions of vitellarium and oocytes of the mated female increased drastically. However, the size of tropharium and number of oocytes present in the vitellarium largely remained unchanged. The process of vitellogenesis also resumed followed by mating stimulus. Therefore, the oocytes were laden with yolk material; at this stage, the surrounded follicular layer is replaced by chorion.
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