author(s)
Samar Mahmood, Mohammad Amir, Ritika Gupta and Shagufta Yasmeen

abstract
Red cotton stainer is a serious pest of cotton crops. It is found damaging crops in Pakistan, South-eastern Asia and various states of India-Gujarat, Uttar Pradesh, Bihar, Madhya Pradesh and Tamil Nadu. It occurs on malvaceous (e.g. okra) as well as non-malvaceous (e.g. sweet potato) plants as well. It damages cotton crops either by feeding on the seeds and staining them through their excreta or by transmitting cotton staining fungi. In present study, the effect of chlorpyrifos was studied on the reproductive organs of both the male and female of Dysdercus koenigii to gain information for control of their population. Chlorpyrifos in the concentration 0.005% and 0.01% was given in the feed of D. koenigii and observations were made after 24 hours treatment with insecticide. The ovaries of D. koenigii are of the telotrophic meroistic type in which, a large amount of yolk in the oocytes is localized in the vitellarium. The treated ovaries showed a considerable reduction in the amount of yolk resulting in the vacuolization and resorption of yolk which show greater damage at higher concentration. In testes major changes were found in germ cells especially spermatozoa, which were either assembled in irregular groups or adhered to each other. At high concentration (0·01%) the spermatozoa were found damaged altogether showing irregular clumping and disrupted structure. The degeneration observed in these organs were directly proportional to the concentration of chlorpyrifos used.