Lepidopterous stem borers of maize (Zea mays): agro-ecological and regional composition and distribution of their parasitoids in Southern Ghana

Abstract

The study aimed at finding out the level of infestation of maize stem borers, their agro-ecological and regional composition and distribution of their parasitoids. Farms were made at University of Cape Coast in the major and minor cropping seasons and maize sown. Plant infestation was recorded weekly. Stem borer larvae and pupae collected from plants were reared until either parasitoids developed from them or they developed into pupae or adults. Rate of parasitization of each stem borer was calculated. In two national maize field surveys, field infestation by pests and parasitism were determined. Parasitoids that emerged from stem borer larvae and pupae were identified to species level. Diversity and distribution of parasitoids according to agro-ecological zones and national administrative regions were determined. Higher stem borer infestation was recorded in the minor season experimental plants. Also, higher number of stem borers was collected from plants during the minor season. Eldana saccharina was the most parasitized stem borer in the experimental farms. Surveys showed more parasitization of stem borers in the minor season. Ashanti and Western regions recorded the highest diversity of parasitoids and Eastern Region recorded the most abundant parasitoids. From both experimental farm and survey results Syzeuctus sp. was the most important parasitoid species of maize stem borers. These results provide useful information on the biology and activities of parasitoids that can be exploited for managing maize stem borers.