Effect of Previous Insecticide Exposure to Parental Weevil on Entomological Variables of their Offsprings on Infested Cowpea Seeds

The objective of this paper was to investigate the effect of previous insecticide exposure to parental weevil on entomological variables of their offsprings on infested cowpea seeds using appropriate standard methods with a ccompletely randomized block design. Entomological variables such as duration of immature development, daily adult emergence and reproductive performance of Callosobruchus maculatus were recorded. The study also identified baseline implications of previous exposure of cowpea to insecticide on the F1 progeny of C. maculatus. On the duration of immature development of life stages of C. maculatus, there was significant (p < 0.05) increase in the duration of development starting from egg hatching, total larval, pupal and immature duration with increase in insecticide concentration (ranging from 2.52±0.03 to 4.83±0.09; 10.90±0.03 to 14.19±0.08 and 17.43±0.19 to 20.22±1.43. days, respectively, for cowpea weevils raised on untreated grains to previously exposed to highly treated grains and exposed to next treated grain, respectively). While egg fertility and adult survivorship ranged from 32.60±6.29 to 79.15±9.29 and 24.34±3.53 to 54.22±4.28 respectively. In conclusion the study has highlighted that effect of prior exposure of the parental generation of C. maculatus to insecticide on the F1 progeny exhibited significant increases in the duration of immature development.