Lepidopteran cereal stemborers and associated natural enemies on maize and wild grass hosts in Cameroon

Abstract

In Cameroon, the noctuid Busseola fusca is the most important pest of maize. The braconid Cotesia sesamiae, which is the most common larval parasitoid of noctuid stemborers in eastern Africa, was absent on B. fusca attacking maize. Thus, it is planned to introduce several strains of the parasitoid from Kenya. Pre-release surveys were undertaken in major maize growing areas to catalogue stemborer species, and larval and pupal parasitoids on maize and four wild host plant species. On maize, B. fusca was the predominant borer in all ecozones except for the lowland coastal forest, usually accounting for 60-99%, followed by the pyralid Eldana saccharina in the forest zone and the crambid Chilo sp. in the mid-altitudes. Contrary to what was reported before, the noctuid Poeonoma serrata -and not B. fusca -was the predominant borer on elephant grass, constituting 70-96% of all borers. On wild sorghum in the forest zone, the noctuid Sesamia poephaga was the most abundant species, while on Panicum sp., Chilo sp. predominated. On Setaria megaphylla in the forest zone, Chilo sp. was the most abundant species followed by Busseola quadrata. Busseola fusca was scarce on all wild grass species, indicating that previous reports on the predominance of this pest species on wild host plants were the result of misidentifications. Three tachinid and 16 hymenopteran parasitoids were obtained, most of them from B. fusca and P. serrata, on maize and Pennisetum purpureum respectively. C. sesamiae was scarce and never recovered from B. fusca on maize. In view of the new findings, acceptability and suitability studies involving the different stemborer species identified from wild plant hosts are required to determine if they will form a reproductive sink or perennate C. sesamiae populations during the off-season when maize is scarce and B. fusca is diapausing.

Physiological suitability of six West African gramineous borers (Lepidoptera: Noctuidae, Pyralidae) for development of Cotesia species complex (Hymenoptera: Braconidae)

“…A C. sesamiae biotype from inland Kenya successfully developed on B. fusca while the coastal strain was completely encapsulated by B. fusca (Ngi-Song et al, 1998;Zhou et al, 2003). A number of surveys have shown that C. sesamiae is rare in western Africa (Bosque-Pérez et al, 1995;Conlong, 2001;Ndemah et al, 2001Ndemah et al, , 2007, whereas in East and southern Africa, it is a common parasitoid of S. calamistis and B. fusca (Ingram, 1958;Kfir and Bell, 1993;Kfir, 1995Kfir, , 1998.…”

“…Economic damage to cultivated gramineous crops in West Africa is restricted to the forest and forestsavanna transition zones, and the mid-altitude region (Schulthess et al, 1997). Extensive surveys conducted in several western African countries showed that larval parasitization of stemborers was generally low and considered insufficient for stemborer suppression in agricultural crops (Gounou et al, 1994;Bosque-Pérez et al, 1995;Conlong, 2001;Ndemah et al, 2001Ndemah et al, , 2007.…”

Phylogenetic analysis and systematics of the Acrapex unicolora Hampson species complex (Lepidoptera, Noctuidae, Apameini), with the description of five new species from the Afrotropics

“…Until recently, very little was known about Acrapex host preferences as specimens had been obtained mainly from light trap collections. Extensive surveys conducted since 2004 (Le Ru et al 2006Ru et al a, 2006bOng'amo et al 2006Ong'amo et al , 2013Ong'amo et al , 2014Ndemah et al 2007;Matama-Kauma et al 2008;Moolman et al 2014) in several sub-Saharan countries, targeting wild habitats rich in Poaceae and combining infested host plant collections and light traps, allowed us to obtain several hundred specimens of Acrapex. A recent study by Le Ru et al (2014) focused on a LE RU B. et al, Contribution to Acrapex systematics 3 small group of morphologically related species belonging to subsets of two (groups B and C) of the four morphological groups that have been defined by Berio (1973) based on male genitalia.…”

Parasitism Rate of Egg Parasitoid Anastatus orientalis (Hymenoptera: Eupelmidae) on Lycorma delicatula (Hemiptera: Fulgoridae) in China

“…Different biotypes of Cotesis sesamian had been successfully introduced into Cameroon for controlling Busseola fusca (Ndemah et al, 2007). So, when choosing natural enemies for biological control program, the different biotypes even from the same species of parasitoid wasp need to be considered carefully.…”