Monitoring wild silkmoth, Gonometa postica Walker, abundance, host plant diversity and distribution in Imba and Mumoni woodlands in Mwingi, Kenya

Abstract

A survey of the abundance of larvae and pupae of Gonometa postica Walker and their host plants was undertaken in the long rainy season in 2006 at six sites in the Imba and Mumoni forests of Mwingi, eastern Kenya. One hundred trees of the primary host species of G. postica were sampled at each site, in addition to minor host species with G. postica pupae. The density of each tree species was calculated and the height, canopy, diameter and number of branches were measured. In order of decreasing abundance, the host plants in Imba forest were Acacia tortilis, A. elatior and A. nilotica, and in Mumoni forest, A. tortilis, A. nilotica, A. mellifera and A. brevispica. A. elatior had significantly more larvae than the other host plants in Imba. In Mumoni, A tortilis and A. mellifera had significantly more larvae, followed by A. nilotica and A. brevispica. The minor host plants harbour significantly more pupae than the major host plants in the two forests. In general, Imba had a significantly higher abundance of larvae and pupae than Mumoni. Host plant species richness did not differ between the two forests, but their evenness was significantly higher in Imba than in Mumoni.