Genetic structure and origin of Busseola fusca populations in Cameroon

Abstract

The cereal stem borer Busseola fusca Fuller (Lepidoptera: Noctuidae) is a species endemic to sub‐Saharan Africa. It is a major pest of maize and cultivated sorghum, the main cereal crops on the African mainland. Previous studies using mitochondrial markers revealed the presence of three clades of haplotypes (W, KI, KII) among B. fusca populations. Previous preliminary studies based on a few B. fusca individuals collected from three localities within the Guineo‐Congolian rain forest in Cameroon demonstrated a matching with clade KII, a fairly surprising result because the putative centre of origin of that clade is located 3 000 km away in East Africa. To check this finding, 120 individuals of B. fusca covering several Cameroonian sites belonging to both Guineo‐Congolian rain forest and Afromontane vegetation mosaics were collected. Comparison of cytochrome b sequences using the same marker revealed low mitochondrial diversity (h = 0.483 ± 0.054, π = 0.073 ± 0.061%). Moreover, molecular diversity in the Guineo‐Congolian rain forest zone was lower than that in Afromontane vegetation, which is therefore thought to be the likely starting point for the colonization of other zones in Cameroon. The study showed a moderate but significant structuring between populations (ΦST = 0.034, P<0.001) as well as within and among the two Cameroonian phytogeographical groups considered (ΦSC = 0.000 and ΦCT = 0.051, respectively, both P<0.001). Nested clade phylogeographic analysis indicated that all Cameroonian clades with significant geographical associations were interpreted as a phenomenon of contiguous range expansion. All results suggest that the Cameroonian population of B. fusca is relatively recent and originates from the recent geographical expansion of clade KII.

Effect of temperature on the life history parameters of noctuid lepidopteran stem borers, Busseola fusca and Sesamia calamistis

“…The observed differences in physiological adaptation suggest that S. calamistis and B. fusca are composed of several ecologically differentiated populations. Such ecologically differentiated populations are in agreement with recent results on B. fusca and S. calamistis reporting genetic differentiation of populations (Sezonlin et al, , ; Ong'amo et al, ).…”

Genetic Diversity in Apple Fruit Moth Indicate Different Clusters in the Two Most Important Apple Growing Regions of Norway

“…This result is similar to the one obtained in the Lepidoptera species "Plutella xylostella" [51]. For the same species, in Cameroon and China substantial genetic variation and high gene flow among regions have been reported [52,53]. However, recent studies also provide contrasting results and have reported genetic differentiation and isolated populations in Lepidoptera species such as for Boloria eunomia, Sesamia nonagriodes and Diatraea saccharalis [48,49,54].…”

Phylogeography in continuous space: coupling species distribution models and circuit theory to assess the effect of contiguous migration at different climatic periods on genetic differentiation in Busseola fusca (Lepidoptera: Noctuidae)

“…In the noctuid Trichoplusia ni (H€ ubner), genetic analyses revealed long-distance dispersion from west to east among North American populations, but geographic areas with large greenhouse populations showed high isolation by distance, correlated with Bt resistance differentiation (Franklin et al 2010). Our results suggest that B. fusca is a good disperser: (i) the same microsatellite cluster is present from southern Africa to southern Cameroon, confirmed by the extension of East African mitochondrial clades in Cameroon (Sezonlin et al 2006(Sezonlin et al , 2012; (ii) apart from the east-west separation (0% introgression), the clusters exchanged migrants (9.0% introgression between the eastern and southern clusters). Locally, Btfree refuge strategy or the plantation of a certain area with non-Bt plants may help to delay the apparition of resistance.…”

“…Our results suggest that B. fusca is a good disperser: (i) the same microsatellite cluster is present from southern Africa to southern Cameroon, confirmed by the extension of East African mitochondrial clades in Cameroon (Sezonlin et al . , ); (ii) apart from the east–west separation (0% introgression), the clusters exchanged migrants (9.0% introgression between the eastern and southern clusters). Locally, Bt ‐free refuge strategy or the plantation of a certain area with non‐ Bt plants may help to delay the apparition of resistance.…”