Oviposition by European Corn Borer (Lepidoptera: Crambidae) in Response to Various Transgenic Corn Events

Oviposition preference by European corn borers, Ostrinia nubilalis (Hubner), for or against transgenic corn would influence amounts of refuge required for resistance management. The objective of this research was to determine if various Bacillus thuringiensis (Bt) corn transgenic events influence 0. nubilalis oviposition. All commercially available events (currently 5) were evaluated, plus 1 experimental event. Results from 3 independent studies are reported, including 3 field-cage experiments with vegetative corn, 2 field-cage experiments with reproductive corn, and 2 field experiments with natural 0. nubilalis on reproductive corn. In each case, Bt corn hybrids are compared with their near isogenic hybrids by counting numbers of egg masses on each plant type. More extensive comparisons were made in 3 of the experiments by determining the number, size, and location of egg masses on the corn hybrids. Moths laid more egg masses on Bt corn than on non-Bt corn in 1 cage experiment. These results, however, were not found in any of the other experiments. There is evidence that suggests cage effects influence moth oviposition more than Bt protein. Four of the 5 cage experiments and 2 field experiments indicate that the tested Bt events do not influence 0. nubilalis oviposition. Larval injury to isogenic corn during the vegetative stage did not influence adult oviposition during the corn reproductive stage when compared with Bt corn and noninjured isogenic corn. Based on these experiments, suggestions are made for future studies that use natural 0. nubilalis rather than 0. nubilalis in cages

Bacillus thuringiensis plants expressing Cry1Ac, Cry2Ab and Cry1F are not toxic to the assassin bug, Zelus renardii

Cotton‐ and maize‐producing insecticidal crystal (Cry) proteins from the bacterium, Bacillus thuringiensis (Bt), have been commercialized since 1996. Bt plants are subjected to environmental risk assessments for non‐target organisms, including natural enemies that suppress pest populations. Here, we used Cry1F‐resistant Spodoptera frugiperda (J.E. Smith) and Cry1Ac and Cry2Ab‐resistant Trichoplusia ni (Hübner) as prey for the assassin bug, Zelus renardii (Kolenati), a common predator in maize and cotton fields. In tritrophic studies, we assessed several fitness parameters of Z. renardii when it fed on resistant S. frugiperda that had fed on Bt maize expressing Cry1F or on resistant T. ni that had fed on Bt cotton expressing Cry1Ac and Cry2Ab. Survival, nymphal duration, adult weight, adult longevity and female fecundity of Z. renardii were not different when they were fed resistant‐prey larvae (S. frugiperda or T. ni) reared on either a Bt crop or respective non‐Bt crops. ELISA tests demonstrated that the Cry proteins were present in the plant at the highest levels, at lower levels in the prey and at the lowest levels in the predator. While Z. renardii was exposed to Cry1F and Cry1Ac and Cry2Ab when it fed on hosts that consumed Bt‐transgenic plants, the proteins did not affect important fitness parameters in this common and important predator

Monarch Butterflies and Bt Corn: Replacing Hoopla with Science

A correspondence to Nature three years ago reported a preliminary laboratory study that suggested pollen from from Bacillus thuringiensis (Bt) com could be hazardous to the larvae of the monarch butterfly, Danaus plexippus. Losey et al. (1999) showed that young monarch larvae given no choice but to feed on milkweed, Asclepias curassavica, leaves dusted with pollen from Bt corn hybrid ate less, grew more slowly, and had a significantly higher mortality rate than larvae feeding on leaves dusted with nontransgenic pollen. Based on this study, the authors questioned the environmental safety of Bt com and called for scientific investigations