Insecticidal Cry proteins from Bacillus thuringiensis (Bt) can be transferred from genetically engineered crops to herbivores to natural enemies. For the lady beetle Harmonia axyridis, we investigated potential uptake of Cry proteins from the gut to the body and intergenerational transfer. Third and fourth instar H. axyridis fed with pollen or spider mites from SmartStax maize contained substantial amounts of Cry1A.105, Cry1F, Cry2Ab2, Cry3Bb1, and Cry34Ab1. Cry protein concentrations in lady beetle larvae were typically one order of magnitude lower than in the food. When H. axyridis larvae were fed Bt maize pollen, median amounts of Cry protein in the non-feeding pupae were below the limit of detection except for small amounts of Cry34Ab1. No Cry protein was detected in pupae when spider mites were used as food. Cry protein concentrations decreased quickly after H. axyridis larvae were transferred from pollen or spider mites to Bt-free food. Aphids contained very low or no detectable Cry protein, and no Cry protein was found in H. axyridis larvae fed with aphids, and in pupae. When H. axyridis adults were fed with Bt maize pollen (mixed with Ephestia kuehniella eggs), the median concentrations of Cry proteins in lady beetle eggs were below the limit of detection except for Cry34Ab1 in eggs laid later in adult life. No Bt protein was detected in eggs laid by H. axyridis females fed with aphids from Bt maize. Our results confirm previous observations that Cry proteins are degraded and excreted quickly in the arthropod food web without evidence for bioaccumulation. Despite the fact that small amounts of Cry proteins were detected in some samples of the non-feeding pupal stage of H. axyridis as well as in eggs, we conclude that this route of exposure is unlikely to be significant for predators or parasitoids in a Bt maize field.

In order to study the co-existing environment of pests and economic animals, the toxicity of 15 insecticides to Plutella xylostella, Monopterus albus, and Paramisgurnus dabryanus was tested. Combined with the recommended maximum doses in the field and bioassay, the results showed that for the three insecticides that were of relatively low toxicity to M. albus and P. dabryanus, spinetoram showed the best control effect on P. xylostella, followed by chlorfenapyr and chlorantraniliprole. However, P. xylostella showed a relatively high resistance to chlorfenapyr. Therefore, the best insecticide suitable for the fields with the cauliflower-finless eel or cauliflower-loach planting and rearing combination was spinetoram, followed by chlorantraniliprole and chlorfenapyr. Other insecticides such as emamectin benzoate, Bacillus thuringiensis (Bt), matrine, and so on were effective against the diamondback moth, but they were not suitable for use because of their high toxicity to the finless eel and loach.

Common varieties of genetically modified (GM) cotton increasingly display insect-resistant properties via expression of bacterial-derived toxins from Bacillus thuringiensis (Bt). This necessitates a deeper understanding of the possible effects of these crops on non-target insects. The mirid bug Apolygus lucorum is a major pest in cotton production in China, however, the effect of GM cotton on this non-target species is currently virtually unknown. This insect is exposed to these transgenic plants by consuming genetically modified (GM) leaves. In this study, laboratory experiments were conducted to assess the toxicity of CCRI41 and CCRI45, (genetically modified cotton varieties which express the toxins Cry1Ac and CpTI (Cowpea Trypsin Inhibitor)) on nymphs and adults of A. lucorum. There was no detectable increase in mortality after A. lucorum fed on GM cotton leaves for 20 days. While we detected trace amounts of Cry1Ac proteins in both A. lucorum nymphs and adults (<10 ng/g fresh weight), the expression of genes related to detoxification did not detectably differ from those feeding on non-GM cotton. Our binding assays did not show Cry1Ac binding to receptors on the midgut brush border membrane from either A. lucorum nymphs or adults. Our findings collectively indicate that feeding on leaves of the GM cotton varieties CCRI41 and CCRI45 have few toxic effects on A. lucorum.

The widespread cultivation of transgenic Bt cotton makes assessing the potential effects of this recombinant crop on non-target organisms a priority. However, the effect of Bt cotton on many insects is currently virtually unknown. The plant bug Adelphocoris suturalis is now a major pest of cotton in southern China and the beetle Haptoncus luteolus is one of the most ancient cotton pollinators. We conducted laboratory experiments to evaluate the toxicity of the Bt cotton varieties ZMSJ, which expresses the toxins Cry1Ac and Cry2Ab, and ZMKCKC, which expresses Cry1Ac and EPSPS, on adult A. suturalis and H. luteolus. No significant increase in the mortality of either species was detected after feeding on Bt cotton leaves or pollen for 7 days. Trace amounts of Cry1Ac and Cry2Ab proteins could be detected in both species but in vitro binding experiments found no evidence of Cry1Ac and Cry2Ab binding proteins. These results demonstrate that feeding on the leaves or pollen of these two Bt cotton varieties has no toxic effects on adult A. suturalis or H. luteolus.

With the commercialization of transgenic cotton that expresses Bt (Bacillus thuringiensis) insecticidal proteins, mirid bugs have become key pests in cotton and maize fields in China. Genetically engineered (GE) crops for controlling mirids are unavailable owing to a lack of suitable insecticidal genes. In this study, we developed and validated a dietary exposure assay for screening insecticidal compounds and for assessing the potential effects of insecticidal proteins produced by GE plants on Apolygus lucorum, one of the main mirid pests of Bt cotton and Bt maize. Diets containing potassium arsenate (PA) or the cysteine protease inhibitor E-64 were used as positive controls for validating the efficacy of the dietary exposure assay. The results showed that with increasing concentrations of PA or E-64, A. lucorum larval development time was prolonged and adult weight and fecundity were decreased, suggesting that the dietary exposure assay was useful for detecting the toxicity of insecticidal compounds to A. lucorum. This assay was then used to assess the toxicity of Cry1Ab, Cry1Ac, Cry1F, Cry2Aa, and Cry2Ab proteins, which have been transformed into several crops, against A. lucorum. The results showed that A. lucorum did not show a negative effect by feeding on an artificial diet containing any of the purified Cry proteins. No significant changes in the activities of digestive, detoxifying, or antioxidant enzymes were detected in A. lucorum that fed on a diet containing Cry proteins, but A. lucorum fitness was reduced when the insect fed on a diet containing E-64 or PA. These results demonstrate that A. lucorum is not sensitive to the tested Cry proteins and that the dietary exposure assay is useful for evaluating the toxicity of insecticidal compounds to this species.

One important concern regarding the use of transgenic cotton expressing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) is its potential detrimental effect on non-target organisms. The honey bee (Apis mellifera) is the most important pollinator species worldwide and it is directly exposed to transgenic crops by the consumption of genetically modified (GM) pollen. However, the potential effects of Bt cotton on A. mellifera remain unclear. In the present study, we assessed the effects of two Bt cotton varieties; ZMSJ expressing the Cry1Ac and Cry2Ab insecticidal proteins, and ZMKCKC producing Cry1Ac and EPSPS, on A. mellifera. Feeding on pollen from two Bt cotton varieties led to detection of low levels of Cry toxins (<10 ng/g fresh weight) in the midgut of A. mellifera adults, yet expression of detoxification genes did not change significantly compared to feeding on non-Bt cotton. Binding assays showed no Cry1Ac or Cry2Ab binding to midgut brush border membrane proteins from A. mellifera adults. Taken together, these results support minimal risk for potential negative effects on A. mellifera by exposure to Bt cotton.

The impact of Bt proteins on non-target arthropods is less understood than their effects on target organisms where the mechanism of toxic action is known. Here, we report the effects of two Bt proteins, Cry1Ab and Cry1Ac, on gene expression in the non-target collembolan, Folsomia candida. A customized microarray was used to study gene expression in F. candida specimens that were exposed to Cry1Ab and Cry1Ac. All selected transcripts were subsequently confirmed by qPCR. Eleven transcripts were finally verified, and three of them were annotated. The responses of all eleven transcripts were tested in specimens for both Cry1Ab and Cry1Ac at a series of concentrations. These transcripts were separated into two and three groups for Cry1Ab and Cry1Ac, respectively, depend on their expression levels. However, those eleven transcripts did not respond to the Bt proteins in Bt-rice residues.