Biology and morphometric measurement of cowpea weevil, Callosobruchus maculatus fabr. (Coleoptera: Chrysomelidae) in green gram

Abstract

A study was conducted in the Laboratory of Entomology, D.M. College of Science, Imphal during May to June, 2013 at 28.5 ±2.0 0C and 78.5± 3.0% relative humidity to study the biology and morphometry of Callosobruchus maculatus .The life cycle consisted of egg, four larval instars (L1, L2, L3 and L4), pupa and adult. The eggs hatched in 6-7 days. The larval duration varied from 18-22 days. The morphometric measurements revealed that the average length and breadth of egg were 0.47± 0.08 mm and 0.12± 0.21 mm respectively. The mean length and breadth of L1, L2, L3 and L4 were 0.60± 0.03 mm, 1.19± 0.05 mm, 2.43± 0.15 mm, 3.64± 0.18 mm and 0.22± 0.03 mm, 0.77± 0.02 mm, 1.22± 0.08 mm, 2.00± 0.11 mm respectively. The average length of male pupa and female pupa was 4.07± 0.00, 4.57± 0.07 mm and breadth was 2.35± 0.07 mm, 2.60± 0.06 mm respectively. The average length and breadth of male and female adult was 3.21± 0.06 mm, 3.70±0.12 mm and 1.91± 0.05 mm, 2.17±0.05 mm respectively. The life cycle took 45-48 days for completion.