The Response of Cowpea Bruchid, Callosobruchus maculatus (Coleoptera: Bruchidae) to some Cowpea Varieties under Short- and Long-Term Storage Conditions

Abstract

Callosobruchus maculatus is causing a considerable loss in stored cowpea in sub-Saharan Africa. The pest responds differently to different cowpea varieties; therefore, understanding the response of the cowpea bruchid to different cowpea varieties will help design better pest management during storage. SAMPEA-20T is a newly released cowpea variety resistant to cowpea pod borer. The response of C. maculatus to SAMPEA-20T has not been studied under storage conditions. A study was conducted to evaluate the response of C. maculatus to SAMPEA-20T along with other varieties of cowpea; SAMPEA-10, Kanannado and Ife-brown under short- and long-term storage. A hundred grams of each of the four varieties of cowpea were infested with 5 pairs of 1-2 days old adults C. maculatus. The experiment was laid out in a Completely Randomized Design (CRD) with three (3) repetitions. Observations were made on adult mortality, progeny emergence, percentage grain damage, and weight loss in short-term (30 days) and long-term (120 days) storage. The result indicated that SAMPEA-10 recorded significantly the highest adult mortality followed by SAMPEA-20T, Kanannado, and Ife-brown, of which no mortality was recorded. Progeny emergence at short and long-term storage was significantly higher in Ife-brown followed by Kanannado, SAMPEA-20T and SAMPEA-10 which had the least number of adult emergences at both short and long-term storage. There was a significantly higher percentage of grain weight loss and damage at long-term storage for Ife brown, than Kanannado, SAMPEA-20T and then SAMPEA-10 with the least. SAMPEA-20T significantly had the highest germination percentage than Kanannado which was statistically similar to SAMPEA-10 but significantly higher than that recorded for Ife-Brown. This study has shown that all varieties were susceptible to C. maculatus infestation, but SAMPEA-20T and SAMPEA-10 had a lesser infestation than Kanannado and Ife-brown.