Effect of Temperature and Humidity on the Biology and Morphometric Measurement of Groundnut Bruchid (Caryedon serratus Olivier) [Coleoptera: Bruchidae] in Groundnut Seed

Abstract

The experiment determined the effects of varying temperatures and relative humidity on the biology and morphometrics of Caryedon serratus. The temperatures were 30, 35, and 40⁰C and relative humidity differences were 60, 65, and 70%. The results show that eggs hatched in 3-4 days at 30⁰C and 60% RH, 4-5 days at 35⁰C and 65% RH, 6-7 days at 40⁰C and 70% RH respectively. Larval period ranges from 19-23 days at 30 ̊C and 60% RH, 14-18 days at 35 ̊C and 65% RH, 14-18 days at 40 ̊C and 70% RH respectively. The morphometric measurements showed that the average length and breadth of eggs were 0.58 mm and 0.15 mm. The mean length and breadth of larval stages were 0.69, 1.27, 2.52, 3.58 mm and 0.35, 0.86, 1.35, and 2.10 mm respectively. The average length and breadth of the pupa were 4.60 mm and 3.00 mm. The mean length and breadth of adults were 4.10 mm and 3.40 mm. The life cycle of bruchid took 33-40, 14-18, and 16-20 days to complete at temperature degrees of 30, 35, 40⁰C and relative humidity ranges of 60, 65, and 70%. Therefore, this work has recommended that the standard optimum temperature and humidity for the best performance of C. serratus particularly on stored groundnut seeds ranges between 30-35⁰C and 60-65% RH. Farmers and all those involved in the storage of groundnut are admonished to be cautious of this period.