INCIDENCE OF HELICOVERPA-ARMIGERA (LEPIDOPTERA, NOCTUIDAE) AND ITS NATURAL ENEMIES ON SMALLHOLDER CROPS IN KENYA

Smallholder crops (sunflower, maize, sorghum and cotton) were grown in experimental plots at seven sites, representing different agricultura l zones of Kenya, over four seasons. Helicoverpa armigera (Hubner) (fo rmerly Heliothis armigera) only occasionally achieved population densi ties sufficient to cause obvious damage to the crops, and was virtuall y absent from the coastal sites. At the inland sites, infestation and mortality levels varied greatly. Information is presented on the incid ence of H. armigera, and the identity, distribution and frequency of i ts common parasitoids and (potential) predators, sampled in the experi mental plots. Trichogrammatoidea spp., egg parasitoids, and Linnaemya longirostris (Macquart), a tachinid late-larval parasitoid, were the m ost common parasitoid species, but total percentage parasitism was rat her low. Of the large complex of predators, only anthocorids and ants (predominantly Pheidole spp., Myrmicaria spp. and Camponotus spp.) wer e sufficiently common and widespread to be of importance in suppressin g H. armigera. The abundance of predators fluctuated widely between si tes, but anthocorids were most abundant at the western sites.