Parasitoids of the African stem borer, Busseola fusca (Lepidoptera: Noctuidae), in South Africa

Abstract

AbstractEighteen parasitoids were recorded from the African stem borer, Busseola fusca (Fuller), on maize and grain sorghum, in Delmas and Cedara, South Africa. In Delmas, larval parasitism on both crops fluctuated below 20% with occasional peaks of 40–60%. In Cedara, larval parasitoids were active throughout the season with peaks of 75% and 60% parasitism during January and March-April, respectively on the ratoon crop, and 20% in May on the crop. Pupal parasitism peaked in Cedara at 100% during February-March, and at 80% during November, when parasitoids attacked pupae that formed after B. fusca larvae had emerged from diapause and pupated. In Delmas activity by pupal parasitoids was negligible. The egg parasitoids, Telenomus busseolae Gahan (Hymenoptera: Scelionidae) and Trichogrammatoidea lutea Girault (Hymenoptera: Trichogrammatidae), were rare. The larval parasitoid, Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae), was active throughout the season and was by far the most abundant, emerging from about 90% of parasitized larvae. Its cocoons were often attacked by Aphanogmus fijiensis (Ferrière) (Hymenoptera: Ceraphronidae). Second in abundance among the larval parasitoids was Bracon sesamiae Cameron (Braconidae) whose cocoons were attacked in turn by Eurytoma braconidis Ferrière (Hymenoptera: Eurytomidae). Eurytoma braconidis was reared also from cocoons of Euvipio sp. and Aleiodes sp. (both Braconidae). All other larval parasitoids were rare. Procerochasmias nigromaculatus (Cameron) (Hymenoptera: Ichneumonidae) was the most abundant pupal parasitoid. Trichogrammatoidea lutea, Glyptapanteles maculitarsis (Cameron) (Braconidae) and Odontepyris transvaalensis (De Buysson) (Hymenoptera: Bethylidae) have not been recorded before from B. fusca. Some considerations and proposals for introductions of parasitoids into South Africa against B. fusca are discussed.