Laboratory experiment was carried out to estimate the effects of gamma radiation from Cobalt-60 source on different developmental stages (egg, larvae, pupae and adult) of Callosobruchus maculatus (F.) at 27 ± 3⁰C and 48 ± 5 % relative humidity (RH). Five different doses (0, 20, 40, 60 and 80 Gray) were used against different immature stages of C. maculatus. Eggs (Two and four days old), larvae (eight and twelve days old), pupae (fifteen and eighteen days old) along with mung bean seeds were irradiated at a dose of 0, 20, 40, 60 and 80Gy respectively. Data was recorded daily for about a month after irradiation. There were 5 treatments and each treatment was repeated thrice. Complete randomized design (CRD) was used for the said experiments. A dose of 20Gy caused complete mortality in two days old eggs whereas 100 percent mortality of four days old eggs of C. maculatus was experienced at 40Gy. Similarly, a dose of 80Gy caused 100 percent mortality in eight days old larvae and 92.50 mean percent mortality in twelve days old larvae. The data further showed that a dose of 80Gy caused 95.34 per cent mortality in fifteen days old pupae and 88.50 percent in eighteen days old pupae. Freshly emerged mated pairs of C. maculatus were also irradiated at a dose of 0, 200, 400, 600 and 800Gy respectively. Low dose of 200 Gy caused 18% mortality while the rest were deformed and unable to mate and lay eggs. A 100 percent mortality of the adults were observed at 800Gy. It is evident from the study that gamma irradiation is effective in controlling the main insect pest of pulses and can be used as a safe method to control store grain pests.

Keywords: Pulse beetle, Gamma Irradiation, Pulse, Dose response, Mortality