A TECHNIQUE FOR HANDLING AND SEXING CALLOSOBRUCHUS-MACULATUS (F) ADULTS (COLEOPTERA, BRUCHIDAE)

A simple technique for easy sexing and handling of the cowpea weevil, Callosobruchus maculatus, adults cultured on cowpea seeds without subj ecting them to chilling, anaesthesia or microscopic observation, is de scribed. The beetles were collected by inverting the clear-plastic rea ring container with a pipette inserted through the lid under a light s ource. The enclosed weevils moving towards the light source were easil y sexed by the shape and size of the abdomens, that of the male being shorter, with the dorsal side of terminal segments curved sharply down wards, as compared with the female. Beetles were collected into the pi pette by nudging them off the container wall to obtain the desired num ber and sex ratio. A comparison with chilling and anaesthetization met hods showed that for chilling in particular, there was some mortality of the weevil. This time-saving method can be used for sexing and coll ecting other Callosobruchus species.