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

Abstract

Eighteen 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.

Biology and Management of Economically Important Lepidopteran Cereal Stem Borers in Africa

“…No catches of moths were recorded during winter (June-September). Larval peaks of B. fusca in the field lagged about 4-6 weeks behind the corresponding moth flight peaks (95,96). Omni-directional traps were superior to delta traps for quantitative and qualitative estimation of B. fusca moth populations (95,96,207).…”

“…In the field, C. partellus starts to emerge from diapause in the second part of August, and it continues until the first week of November, a period of 12 weeks. In contrast, B. fusca pupates only during October-November (83,85,95). This difference in the pattern of emergence from diapause by the two borer species explains the distinct generations of B. fusca (54,95,106) and the overlapping generations of C. partellus (85, 205) occurring every year in South Africa.…”

“…Several years of monitoring B. fusca using sex pheromone traps in South Africa (95,96) revealed that the first flight resulting from moths emerging from hibernating borers peaked about the middle of November. The second flight, usually larger, peaked in the second half of February; a third flight, which occurred in Mpumalanga Province, peaked around the middle of April.…”

“…For these cultural control measures to be effective, the cooperation of farmers in a region is required because moths emerging from untreated fields can infest adjacent crops (88). Currently this system is not widely practiced in South Africa because of the advent of minimum tillage and the importance of winter grazing of maize to beef farmers (88,95).…”

Host recognition and acceptance behaviour in Cotesia sesamiae and C. flavipes (Hymenoptera: Braconidae), parasitoids of gramineous stemborers in Africa

“…The most abundant larval parasitoid recovered from stemborers in East and Southern Africa is the gregarious braconid Cotesia sesamiae (Cameron). Parasitism is usually below 5%, though in some localities it can attain 75% (Kfir, 1995;Sallam et al, 1999;Jiang et al, 2006;Songa et al, 2007). Several strains of C. sesamiae from Kenya were introduced into west Africa, where C. sesamiae is very rare, to control B. fusca and S. calamistis (Schulthess et al, 1997;Ndemah et al, 2007).…”