Natural regulation of Helicoverpa armigera larvae by hymenopteran parasitoids in northern Cameroon: Is there scope for application of conservation biological control in cotton agroecosystems?

The conservation biological control (CBC) concept has been explored through research conducted in northern Cameroon on larval parasitism of Helicoverpa armigera, a major cotton pest, on different host plants year round, from early September 2008 to late December 2014. A total of 47,152 caterpillars were reared over the 6-year period. They were found regularly present on crops such as cotton and okra and on wild plants, including Corynandra viscosa and Hyptis spp. The overall percentages of nematode- and disease-infected caterpillars were very low (1.05% and 2.92%, respectively). Diptera species accounted for less than 0.1% of the parasitoids that had emerged from caterpillars. Total hymenopteran parasitism was 10.5%, and varied markedly depending on the host plants. Nine Hymenoptera species were identified, with Meteorus laphygmarum being the dominant one (almost 80% of all 2698 adult parasitoids obtained after rearing), followed by Schoenlandella variegata (16.42%) and Charops spinitarsis (