Attraction of <Callosobruchus maculates fabricius (Coleoptera: Chrysomelidae: Bruchinae) to pods of cowpea plants at different developmental stages

Abstract

The cowpea beetle, Callosobruchus maculatus Fab. is an economically important pest of stored grain and causes serious damage to stored peas. The application of pesticides has been the generic control measure due to its effectiveness, affordability and ease of application. However, due to the apparent health and environmental consequences with pesticides, stakeholders are advocating for an alternative management approach that has less social and environmental impact and is more sustainable. Consequently, this study examined the attraction of mated female to volatile blends collected from pods of cowpea plants (Borno-brown and black-eyed cultivars) at three developmental stages  developing podsie; 15-17 days after anthesis (daa), fully developed pods (18-20 daa) and mature pods (> 20 daa). The beetles’ responses to the pods’ odour were determined using a two-arm olfactometer, and gas chromatography-mass spectrometry (GC-MS) was used to identify and  quantify the volatile compounds collected from the pods. The results showed that female C. maculatus attraction increased with the pod’s age, and that the composition and abundance of volatile compounds varied between cowpea cultivars and the pod’s developmental stage. These findings form an important bases towards developing alternative approach for the management of bruchids.

Key words: volatile compounds, cowpea plants, GC-MS, pod’s developmental stage, days after anthesis