Department of Agricultural Entomology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur - 741 252, Nadia, West Bengal, India.
A laboratory study was conducted at the B.C.K.V., Nadia (West Bengal) during 2001 on the biology of pulse beetle, Callosobruchus chinensis Linn. (Coleoptera: Bruchidae) in stored seeds of green gram, Vigna radiate L. This bruchid completed eight generations within a short period of study i.e. from April to October, 2001. Pre-adult stages of bruchid took 23 days during September when temperature was moderate (29 to 31.0°C) and relative humidity was high (85 to 90%) while immature stages of the beetle was found to be shorter (19 days) during August. The adult longevity of male and female were found to vary from 4.3 to 10.6 and 7.2 to 11.1 days, respectively. Adult longevity irrespective of sex was highest (9.4 days) in eighth generation during mid September to end October, 2001 while it was lowest (7.7 days) in first generation during mid April to mid May, 2001. The number of adults emerged from a single pair of bruchids ranged from 33.3 to 73.5 irrespective of generations studied. Sex ratio was more in favour of male than female. The successful adult emergence was recorded more from the eggs laid during first few days of oviposition (i.e. within 5 days after releasing the adult beetles).
