Habitat management in control of Astylus atromaculatus (Coleoptera: Melyridae) in maize under subsistence farming conditions in South Africa

Abstract

Studies were conducted in South Africa to assess the potential role of a habitat management strategy developed for the control of cereal stemborers in control of Astylus beetle. This strategy involves intercropping maize with a stemborer moth-repellent fodder plant (Desmodium) (‘push’), with a stemborer moth-attractant host plant (Napier grass) (‘pull’), planted as a perimeter/trap crop around the plot (‘push-pull’ system). Treatments were habitat managed plots, comprising of ‘push-pull’ and ‘pull’ plots, and maize monocrop plots (control). A combination of choice tests and field trials were employed to evaluate any impact of this system on Astylus beetle colonization of maize fields. Results showed significant reductions in beetle populations in habitat managed plots (>60 %). Similarly, there was a significant reduction in beetle capture (>50%) in Desmodium-baited yellow water traps in two-choice tests, although the total number of beetles captured was generally low (<50%). In addition, Desmodium caused a reduction of 11–15% in beetle captures in the multiple-choice tests. Habitat management thus shows potential for use in Astlyus beetle management in maize in the affected areas, largely through the barrier effects of Napier grass.