Establishment of Cotesia flavipes (Hymenoptera: Braconidae) in Sugarcane Fields of Ethiopia and Origin of Founding Population

Abstract

Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) is used as a classical biological control agent against Chilo partellus (Swinhoe) (Lepidoptera: Crambidae), a serious exotic pest of cereal crops in eastern and southern Africa. This parasitoid has been introduced into several African countries for the control of C. partellus in maize, Zea mays L., and sorghum, Sorghum bicolor (L.), but it has never been released in Ethiopia. It is hypothesized that it spread into Ethiopia from populations released in Kenya and Somalia to become the predominant parasitoid of C. partellus in maize and sorghum fields of the country. In recent surveys conducted in Ethiopia, C. flavipes was recovered from C. partellus in sugarcane, Saccharum L. spp. hybrids, at a site >2,000 km from the nearest known release sites in Kenya and Somalia. These findings question published hypotheses that estimate the dispersal rate of C. flavipes to be 60 km per year in Africa, and they suggest that since its release in Africa this parasitoid has developed strains adapted to searching particular host plants infested by particular stem borers. The anomalies between our results and previous reports evoked the hypothesis that C. flavipes in Ethiopian sugarcane might be a different strain. To test this hypothesis, we compared partial COI gene sequences of C. flavipes collected from sugarcane in Ethiopia and those of specimens from other African countries to determine the origin of the Ethiopian population. In addition, COI sequences were obtained for C. flavipes from other continents. The C. flavipes population established in Ethiopian sugarcane is most closely related to the populations released against C. partellus in maize in other parts of Africa, which were derived from the original population imported from Pakistan. The dispersal rate of the parasitoid was estimated to be >200 km per year.

Assessing the long-term welfare effects of the biological control of cereal stemborer pests in East and Southern Africa: Evidence from Kenya, Mozambique and Zambia

“…Evidence of the establishment and spread following the release of biological control agents has been highlighted in several studies and surveys (Assefa et al, 2008;Cugala, 2007;Getu et al, 2003;Mailafiya et al, 2011;Moonga, 2007;Omwega et al, 1995Omwega et al, , 1997Omwega et al, 2006;Sallam et al, 2001). In addition, the parasitism-effect and suppression-effect of the released biological control agents has been demonstrated and confirmed the effectiveness in reducing pest densities (Cugala, 2007;Jiang et al, 2006;Zhou et al, 2001).…”

“…With the GIS coordinates of all the release points, we modelled the spread around each release point in the four cardinal directions using concentric circles respecting the year of release and the appropriate specific annual dispersal rate (Gichini et al, 2008;Nordblom et al, 2002). Omwega et al (1997) found the dispersal rate of C. flavipes to be 60 km per year whereas Assefa et al (2008) found it to be higher than 200 km per year. Later, Omwega et al (2006) estimated this dispersal distance to be 11.23 km per year.…”

Genetic footprints of adaptive divergence in the bracovirus of Cotesia sesamiae identified by targeted resequencing

“…The existence of these large continuous populations implies gene flow over long distances and therefore either large dispersal abilities or stable resource availability over large areas. In Africa, C. flavipes , belonging to the same species complex as C. sesamiae, has a dispersal rate estimated to range between 11 and 200 km per year based on biocontrol release and recapture experiments (Assefa, Mitchell, Conlong, & Muirhead, ; Omwega, Muchugu, Overholt, & Schulthess, ). Such dispersal abilities would explain the large population distribution observed in C. sesamiae .…”

“…In Africa, C. flavipes, belonging to the same species complex as C. sesamiae, has a dispersal rate estimated to range between 11 and 200 km per year based on biocontrol release and recapture experiments (Assefa, Mitchell, Conlong, & Muirhead, 2008;Omwega, Muchugu, Overholt, & Schulthess, 2013 (Dupas et al, 2008), which has driven adaptive divergence and resulted in speciation in the case of C. typhae.…”

Survey of Parasitoids and Predator on Asiatic Pennywort Farms in Thailand

“…are important larval parasitoid of various lepidopteran insect pest. C. flavipes is used against Chilo partellus [13]. Chelonus sp.…”