Cereal crops are grown by resource-poor farmers throughout sub-Saharan Africa. Maize is the most important staple food. Grain sorghum is also important because of its drought-resistant properties. The African stem borer, Busseola fusca, and the spotted stem borer, Chilo partellus, are the most destructive pests of cereal crops in southern Africa. Their control is expensive and requires expertise, as precise timing of pesticide applications is crucial. Small-scale farmers very often cannot afford chemical applications against stem borers. Alternative, non-chemical, affordable and sustainable control methods of stem borers in cereal crops are therefore being investigated, with emphasis on biological control.
Stem borers were monitored at Cedara (KwaZulu-Natal Province), Delmas (Mpumalanga Province) and Brits (North-West Province), South Africa. Moth populations of Busseola fusca were monitored with synthetic sex pheromone traps, while larval populations of the two stem borer species were monitored by scouting maize and grain sorghum fields. (read more)
Since the appearance of the stem borer Chilo partellus (Swinhoe) on the African continent in 1932, it has continuously expanded its distribution in the warm, low-altitude regions of eastern and southern Africa. The current study revealed that C. partellus is expanding its distribution into the high elevations of the eastern Highveld region of South Africa. (read more)
In a study in KwaZulu-Natal, South Africa high levels of parasitism of Busseola fusca pupae by the parasitoid Procerochasmias nigromaculatus (Cameron) (Ichneumonidae) were recorded. Up to 100% parasitism was recorded in the middle of the growing season, during February-March, and 80% during November, when borer larvae which had terminated diapause were parasitised after pupation. Larval parasitism mainly by Cotesia sesamiae, which was reared from about 87% of parasitised larvae, peaked at 75% during January. Despite the high parasitism levels by these parasitoids they did not prevent economically significant damage. (read more)
The stem borers, Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae), are the most important pests of maize and grain sorghum in South Africa. Parasitoids, pathogens and predators curtailed populations of B. fusca and C. partellus on the crops but their activity was not enough to reduce pest populations to below economic damage level. They also could not prevent the dispersal and subsequent wide distribution of C. partellus after its introduction into South Africa. (read more)
