Suitability of cereal stemborers in Cameroon to Kenyan populations of the braconid larval parasitoid Cotesia sesamiae

The noctuid Busseola fusca is the most destructive pest of maize in Cameroon. Various habitat management technologies have been developed and tested but none of them provides a self-sustainable solution. The braconid Cotesia sesamiae, the most common larval endoparasitoid of the B. fusca in eastern Africa, is rare in West Africa and Cameroon. In Cameroon, it is mostly found on non-crop borer species feeding on wild grasses. Thus, two Kenyan C. sesamiae populations and their hybrid were introduced into Cameroon. Suitability studies were carried out with two B. fusca populations, the noctuid Poeonoma serrata, which is commonly found feeding on Napier grass but not maize, and the noctuid Sesamiae cretica, which was recently accidentally introduced into Mauritania, where it attacks sorghum. The performance of the C. sesamiae was influenced by both host species/population and parasitoid population, although the B. fusca population had a minor effect. The reproductive potential of the hybrid was superior over that of its parent populations. The least suitable host was P. serrata, thus it was concluded that it would probably not play a major role in perennating C. sesamiae during the dry season. With S. cretica as host, parasitism was similar but brood size was lower than with either B. fusca population. Release strategies of C. sesamiae and its chances of establishment on B. fusca and S. cretica in the hothumid forest zone and the cool highland of Cameroon and in Mauritania are discussed.