Assessment of Potential Toxic Effects of RNAi-Based Transgenic Cotton on the Non-Target Predator Harmonia axyridis

Although traditional genetically modified (GM) cotton has reduced lepidopteran pests, secondary pests such as Adelphocoris suturalis Jakovlev (Hemiptera: Miridae) have become increasingly problematic. RNA interference (RNAi)-based insect-resistant plants offer a promising alternative, but their potential ecological risks, particularly within the plant-pest-natural enemy framework, require comprehensive evaluation. As a key natural enemy in cotton agroecosystems, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) plays a vital role in regulating pest populations and thus serves as an important non-target insect for environmental risk assessment. In this study, dsAsFAR transgenic cotton and the non-target insect H. axyridis were used to evaluate potential ecological risks. Based on the sequences of the HaFAR, AsFAR, and GFP genes, dsAsFAR, dsHaFAR, and dsGFP were synthesized in vitro and incorporated into artificial diets fed to H. axyridis, along with a ddH₂O control group. No significant differences were observed among the treatments across various developmental stages. Furthermore, H. axyridis was fed aphids that had been reared on either transgenic or non-transgenic cotton plants cultivated in a greenhouse. The findings indicated no significant differences in the growth, development, predatory ability, or fecundity of H. axyridis. These results suggest that transgenic dsAsFAR cotton targeting A. suturalis poses no detectable adverse effects on H. axyridis, supporting the environmental safety of RNAi crops within a plant-pest-natural enemy ecological interaction framework. Moreover, the dsAsFAR expressed in transgenic cotton was not effectively transferred through the food chain to affect homologous gene expression in H. axyridis.