Sensitivity of developmental stages of pulse beetle Callosobruchus maculatus (F.) to gamma rays

Abstract

Sensitivity studies on effects of gamma radiation on different life stages of Callasobruchus maculatus (F.) werecarried out in a growth chamber at temperature of 30ºC and relative humidity of 70 per cent. Two days old eggs, grubs (fourand seventeen days old) and three days old pupae along with green gram seeds were exposed to gamma radiation in range of0-50 Gy, 0-60 Gy, 0-100 Gy and 0-100 Gy, respectively. The radiation doses like 15 Gy, 40 Gy, 100 Gy and 100 Gy wereeffectively prevented adult formation from treated pre-imaginal stages mentioned above. For adult beetles response wasassessed by selecting five pairs of four days old adult male and females along with 30 g greengram seeds kept as a food andwere exposed to gamma radiation in range of 0-140 Gy. The fecundity of adults decreased with the increase of irradiationdose. There was 54.02, 61.59, 69.07, 87.80, 94.36 and 97.45 per cent reduction in egg laying in adults exposed to 20, 40, 60,80, 100 and 120 Gy, respectively. The adults exposed to a radiation dose of 80 Gy and above were capable of egg laying butsuch eggs were not developed to form adult . Therefore, from this study we concluded that all stages of C. maculatus canbe killed at 120 to 150 Gy expose dosage of gamma radiation.