Manipulation of Reproductive Potential of the Pulse Beetles Callosobruchus Spp. (Coleoptera : Bruchidae) by Gamma Irradiation

Some important reproductive potentials as fecundity, egg-to-adult developmental period, percent of adult emergence, sex-ratios and adult longevity of the pulse beetles, Callosobruchus chinensis and C. maculatus in response to gamma radiation treatments of 2, 4, 8 and 16 Gy were studied. Results indicate the 8 Gy was effective in suppressing fecundity (P<0.05) and adult emergence (P<0.01) in C. chinensis while a smaller dose was capable of reducing adult emergence only (P<0.001) in C. chinensis. At 16 Gy, developmental period (P<0.05) and adult emergence (P<0.001) in C. chinensis but only developmental period (P<0.05) in C. maculatus were affected adversely. Apparently sex-ratios and adult longevity were not affected by the treatments. In both species, progenies derived from parental generation were more affected than those from F1 or F2 generations. Probit mortality value in C. chinensis (LD50=40.48 Gy) was much higher than that in C. maculatus (LD50=16.99 Gy), and the probit sterility responses (SD50) of the two species were 6.32 Gy and 2.07 Gy, respectively