The ladybird Propylea japonica, adults of the green lacewing Chrysoperla nipponensis and the honey bee Apis mellifera are common pollen feeders in many crop systems. They could therefore be directly exposed to Cry proteins in Bacillus thuringiensis (Bt)-transgenic crop fields by ingestion of pollen. They, or closely related species, are therefore often selected as surrogate test species in non-target risk assessment of Bt plants. In the current study, we evaluated the potential effects of the ingestion of Bt maize pollen containing the Cry1Ab/Cry1Ac fusion protein on various life-table parameters of the three pollen-feeding non-target species in laboratory feeding assays. The results showed that pupation rate and male adult fresh weight of P. japonica were significantly increased when fed pollen from Bt maize compared to control maize pollen, but other test life-table parameters were not affected. For the other two species, none of the tested life-table parameters (survival, pre-oviposition period, fecundity and adult fresh weight for C. nipponensis; survival and mean acinus diameter of hypopharyngeal glands for A. mellifera) differed between non-Bt and Bt maize pollen treatments. ELISA measurements confirmed the stability and uptake of the Cry protein by all three species during the feeding bioassays. In addition, a sensitive insect bioassay confirmed the bioactivity of the Cry1Ab/Cry1Ac protein in the Bt maize pollen used. Overall, the results suggested that the three pollen feeders are not sensitive to the Cry1Ab/Cry1Ac protein, and planting of the Bt maize variety will pose a negligible risk to P. japonica, adult C. nipponensis and adult A. mellifera.

Cnidium monnieri (L.) Cusson (Apiaceae) is a well-known insectary plant in farmlands. Its vegetative and flowering stages can promote the migration of natural enemies. However, the arrival of natural enemies in crop fields often lags behind the establishment of pest populations. As gibberellin can accelerate plant growth and flowering, we investigated whether gibberellin treatment could advance the recruitment of natural enemies by altering the phenology of C. monnieri. Field experiments were conducted in 2021 and 2022 to evaluate the effects of different gibberellin concentrations on plant phenology, growth traits, and natural-enemy abundance. For field validation, C. monnieri strips established in wheat fields were treated with water or 50 mg/L gibberellin. The 50 mg/L treatment advanced the onset of flowering by 21 days and the first detection of natural enemies on C. monnieri by 14 days in 2021 and 20 days in 2022. It also significantly increased natural-enemy abundance on C. monnieri in 2022. In wheat fields, the same treatment resulted in earlier detection and significantly greater abundance of natural enemies in 2022. The earlier detection of natural enemies was temporally consistent with the advancement of flowering. These findings indicate that manipulating the flowering phenology of insectary plants may improve the timing of natural-enemy establishment and strengthen conservation biological control.