Low Temperature Treatments to Control Pulse Beetle, Callosobruchus maculatus in Mungbean

Pulse beetle, Callosobruchus maculatus Fab. is an important pest of mungbean (Vigna radiata L. Wilczek). In the light of hazards posed by pesticides, there is a need to look at alternative physical methods such as thermal treatments to control these storage pests. Seeds infested with different developmental stages (egg stage, early, late larva and pupal stages) of C. maculatus were exposed to low temperatures at 20±1°C, 9±1°C and -14±1°C for 24h. Adult emergence decreased with decrease in temperature and there was no adult emergence at -14±1°C. The growth indices at 20±1°C, 9±1°C revealed that the seeds infested with the early larva were more susceptible followed by late lanva, egg and pupa while at -14±l°C, the growth index was zero for all the stages. Adult survival at -14±1°C declined with exposure periods and was 0 per cent at an exposure period of 60 min. Healthy seeds of mungbean exposed to the above low temperature treatments were tested for seed germination as per the ISTA Rules. The germination of mungbean seeds was observed to be about 75-80 per cent in comparison to 90% in control.