n African Entomology - Effect of Bt-maize expressing Cry1Ab toxin on non-target Coleoptera and Lepidoptera pests of maize in South Africa

Volume 22, Issue 1
  • ISSN : 1021-3589


While many studies have been conducted on possible effects of Bt-maize on beneficial arthropods, information on its effects on non-target pests of maize is scarce. Bt-maize has been planted in South Africa since 1998 for control of the maize stem borers, (Lepidoptera: Noctuidae) and (Lepidoptera: Pyralidae). No information is available on the possible effects that feeding on Bt-maize may have on other pests exposed to Cry1Ab protein when they attack seedlings or ears of Bt-maize. Important pests attacking maize seedlings are (Coleoptera: Scarabaeidae) and (Coleoptera: Tenebrionidae), while (Lepidoptera: Noctuidae) is a sporadic pest of maize ears. The objectives of this study were to determine the effects of Bt-maize, expressing Cry1Ab protein, on these non-target pests. Laboratory studies in which larvae or adults of these species were fed with Bt and non-Bt-maize leaves or ears were conducted and mortality, growth, fecundity and fertility determined. Feeding on Bt-maize did not have a significant effect on any of these life-history parameters of or . In greenhouse and laboratory studies with no larvae survived to the pupal stage on Bt-maize. This study showed that Cry1Ab-producing maize may protect the crop against feeding damage. However, the likelihood of becoming resistant to Cry1Ab protein over time, and it becoming an important secondary pest, is high.

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