Solar heating of seeds — a low cost method to control bruchid ( Callosobruchus spp.) attack during storage of pigeonpea

Bruchids ( Callosobruchus spp.) are major storage pests of legume crops grown in the tropics and sub-tropics including pigeonpea ( Cajanus cajan (L.) Millsp.) and cause considerable economic losses. Solar heating of seeds in transparent polyethylene bags was found to effectively control bruchid damage in seeds of a medium-duration pigeonpea cultivar (ICPL 87119) during prolonged storage. During a week of observation, solar heating raised the temperature in seed bags to 65°C each day. Solar heat-treated seeds remained free from bruchid damage even after 41 weeks of storage. No reduction in seed germination was observed in the solar-heated seeds. The control treatment had up to 91% of bruchid damaged seeds and their germination was reduced to 42%. Farmers in semi-arid tropical and humid tropical regions may consider using solar heating as a safe and relatively inexpensive method for disinfesting seeds of pigeonpea.