Bulletin of Entomological Research

Original Articles

Incidence of Helicoverpa armigera (Lepidoptera: Noctuidae) and its natural enemies on smallholder crops in Kenya

H. van den Berga1 p1, M. J. W. Cocka1 c1, G. I. Oduora2 and E. K. Onsongoa2

a1 International Institute of Biological Control, (an institute of CAB International), Kenya Station, Nairobi, Kenya

a2 Kenya Agricultural Research Institute, Nairobi, Kenya

Abstract

Smallholder crops (sunflower, maize, sorghum and cotton) were grown in experimental plots at seven sites, representing different agricultural zones of Kenya, over four seasons. Helicoverpa armigera (Hübner) (formerly Heliothis armigera) only occasionally achieved population densities sufficient to cause obvious damage to the crops, and was virtually absent from the coastal sites. At the inland sites, infestation and mortality levels varied greatly. Information is presented on the incidence of H. armigera, and the identity, distribution and frequency of its common parasitoids and (potential) predators, sampled in the experimental plots. Trichogrammatoidea spp., egg parasitoids, and Linnaemya longirostris (Macquart), a tachinid late-larval parasitoid, were the most common parasitoid species, but total percentage parasitism was rather low. Of the large complex of predators, only anthocorids and ants (predominantly Pheidole spp., Myrmicaria spp. and Camponotus spp.) were sufficiently common and widespread to be of importance in suppressing H. armigera. The abundance of predators fluctuated widely between sites, but anthocorids were most abundant at the western sites.

(Accepted December 02 1992)

Correspondence:

c1 International Institute of Biological Control, Silwood Park, Buckhurst Road, Ascot, Berks SL5 7TA, UK.

p1 Department of Entomology, Agricultural University P.O. Box 8031, 6700 EH Wageningen, The Netherlands.