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Interactions between Spodoptera frugiperda and two of its natural enemies on conventional and Bt maize hybrids

Year: 2005
Type: dissertation
Abstract: The effects of transgenic Bt maize (Event 176), expressing CrylAb, on S. frugiperda and two of its natural enemies; the parasitoid Campoletis sonorensis and the entomopathogenic fungus Beauveria bassiana, were examined in comparison with those of a conventionally-bred resistant and a susceptible maize hybrid. When fed Bt maize, S. frugiperda larvae showed greater mortality (25%) than larvae fed the two conventional maize hybrids (5%). Bt maize-fed larvae that survived demonstrated sublethal effects, such as an extended development time. The conventionally-bred resistant maize hybrid, selected for field resistance to Ostrinia nubilalis, was shown not to be effective against S. frugiperda as the development of S. frugiperda larvae was similar when reared on the two conventional maize hybrids. No evidence for a direct toxic effect of CrylAb on C. sonorensis was found, but indirect, sublethal effects of Bt maize on C. sonorensis were observed. Adult parasitoids emerging from Bt maize-fed S. frugiperda hosts were smaller than parasitoids emerging from conventional maize-fed hosts. Adult parasitoid size was correlated with the host’s size at oviposition and its subsequent growth rate. The host preference and subsequent development time of C. sonorensis was not affected by the maize hybrid fed to its host. CrylAb was detected in S. frugiperda larvae fed Bt maize, however Cry lAb could not be detected by ELISA in C. sonorensis adults. Mortality of S. frugiperda larvae after exposure to B. bassiana conidia did not significantly differ on the three maize hybrids. However, fewer S. frugiperda larvae showed B. bassiana sporulation after death in the Bt maize treatment compared to both the conventional maize treatments.
Author: Sanders, Christopher J
Language: English
Open Access status: green
OpenAlex ID: W7001251425
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