Implication of mating on oocyte development in red cotton bug, Dysdercus koenigii (Fabricius, 1775) (Heteroptera: Pyrrhocoridae)

Abstract

Abstract 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.