The status of leaf feeding resistance and oviposition preference of Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) for sweet sorghum (Sorghum bicolor) landraces

Abstract

Sweet sorghums are readily attacked by Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) and Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and have potential for use as trap crops for these species. The aim of this study was to assess the status of stem-borer resistance of sweet sorghum landraces and also to determine if they could be used as trap crops for maize stem-borers. Four greenhouse experiments were conducted to evaluate indigenous sweet sorghum landraces for resistance to larval feeding by C. partellus and B. fusca. Plants were artificially infested with first instar larvae of C. partellus and B. fusca. Multiple-choice tests were conducted to determine oviposition preference among different landraces. All the landraces were highly susceptible to both stem-borer species. Some of the highest mean larval masses of B. fusca and C. partellus were recovered from the landraces Motale and Pataletso while some the lowest larval masses were recorded from Mariri and SA4481. These differences were, however, not statistically significant. These varieties were subsequently used in oviposition preference studies. No significant differences in the numbers of eggs per plant on the different sweet sorghum landraces were recorded for any of the stem-borer species. No significant differences were observed in the number of eggs laid by C. partellus on maize and sorghum landraces in any of the two-choice tests. However, B. fusca laid significantly more eggs on maize than on sorghum landraces. None of the sweet sorghum varieties holds promise as trap crop for stem-borers on maize.