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

Abstract

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 hot–humid forest zone and the cool highland of Cameroon and in Mauritania are discussed.

Performance of the newly identified endoparasitoid Cotesia icipe Fernandez‐Triana & Fiaboe on Spodoptera littoralis (Boisduval)

“…Cotesia icipe had a relatively shorter total developmental time (13.3 days) compared to other species of Cotesia such as C. flavipes on Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) (17.9 days; Ngi‐Song, Overholt, & Ayertey, ) and C. sesamiae (Cameron) on Busseola fusca (Fuller) (Lepidoptera: Noctuidae) (16.2 days; Ndemah et al., ). However, this developmental time is similar to the one of C. marginiventris (12–13 days; Kunnalaca & Mueller, ), C. plutellae (12.6 days; Shi, Liu, & Li, ), C. chilonis (Munakata) (12.5 days; Hailemichael, Schulthess, Smith, & Overholt, ), C. rubecula (13.48 days; Harvey, Jervis, Gols, Jiang, & Vet, ) and C. ruficrus (Haliday) (13.2 days; McCutcheon, Salley, & Turnipseed, ).…”

Variation in a Host–Parasitoid Interaction across Independent Populations

“…In the stem-boring moth system, the virulence of the generalist parasitoid Cotesia sesamiae and host resistance have been measured in terms of host encapsulation. Encapsulation rate varies geographically [ 44 ], with parasitoid and host population [ 12 , 45 ], host species [ 7 ], and in association with a Wolbachia endosymbiont [ 12 ]. In each study system, there is evidence that resistance to parasitoids comes at a cost to hosts [ 46 , 47 , 48 ] and that increased virulence comes at a cost to parasitoids [ 46 , 49 , 50 ].…”

Old and new association of Cotesia icipe (Hymenoptera: Braconidae) with alien invasive and native Spodoptera species and key stemborer species: implication for their management

“…parasitoids have been recorded in Cotesia plutellae Cameron (Hymenoptera: Braconidae) on 15 different lepidopteran hosts, 49 as well as in C. sesamiae on B. fusca, Sesamia cretica Lederer and Poeonoma serrata Tams & Bowden (both Lepidoptera: Noctuidae). 50 Notably, differential host physiological suitability for an endoparasitoid is a function of host regulation factors. The factors such as the host's internal environmental conditions, including the sufficiency and suitability of the nutritional source, ultimately shape the outcome of possible completion of parasitoid development.…”

“…Similar findings on differences in the suitability of Cotesia spp. parasitoids have been recorded in Cotesia plutellae Cameron (Hymenoptera: Braconidae) on 15 different lepidopteran hosts, 49 as well as in C. sesamiae on B. fusca , Sesamia cretica Lederer and Poeonoma serrata Tams & Bowden (both Lepidoptera: Noctuidae) 50 . Notably, differential host physiological suitability for an endoparasitoid is a function of host regulation factors.…”