Studies on the biology of pulse beetle (Callosobruchus chinensis Linn.) infesting cowpea

Pulses (grain legumes) are the second most important group of crops worldwide. Globally, 840 million people are under nourished mainly on account of inadequate intake of proteins, vitamins and minerals in their diets. Under stored conditions , pulses suffer maximum grain loss due to dreaded stored grain bruchid pests. Studies on the biology of pulse beetle Callosobruchus chinensis (Linn) (Coleoptera: Bruchidae) on the stored cowpea revealed that the insect completed six generations from April to October. The total developmental period of bruchid was 33 days during July- August while it was 37.3 days during April- May. On average duration of incubation period was 7.13±0.34 and 6.04±0.78 while larval + pupal period was 28.51± 2.06 and 28.12±2.08days in two successive generations. The adult life span for male was 4.76±0.64 days and 6.01±0.13 where as for female 8.36±0.12 and 9.13±0.09 days. The total life span of male and female was 34.24±2.16 days in average. The pre- oviposition, oviposition and post- oviposition periods were 6.36±0.36 hours, 4.21±0.16 days and 4.15±0.42 days, respectively in first generation while these parameters recorded as 5.36±0.16 hours, 5.75±0.64 days and 4.69±0.57 days, respectively in second generation. The average eggs laid by female was 96.4 and 102 while hatchability of eggs recorded as 92% and 95.5% and sex ratio of male and female was 1: 1.04 and 1:1.12 in two successive generations.