Transgenic Cry1Ac+CpTI cotton cultivar may carry an antifeedant effect on the honey bee Apis mellifera

Transgenic Cry1Ac+CpTI cotton is increasingly used throughout the China currently. However, negative effects of this cultivar on the honey bee Apis mellifera L, the most important pollinator for cultivated ecosystem, remain poorly investigated. The objective of our study is to evaluate the potential side effects of Cry1Ac+CpTI pollen on young adult honeybees. Two points emphasize the significance of our study: (a)We detected a higher expression level of insecticidal protein Cry1Ac and CpTI in fresh pollen tissues compared with those reported before. Specifically, the detected protein Cry1Ac reached a level of 300±4.52ppb in fresh pollens collected in July and also a higher dose of CpTI were observed during the flowering period. (b) Effects on chronic mortality and feeding behaviour in honey bees were conducted by using a no-choice dietary feeding protocol with treated pollens, which guarantee a higher exposure level to bees than natural conditions. Also, the same effects were tested using imidacloprid at the concentration of 48 ng/g evenly mixed up in pollens as positive control. Our results suggested that Cry1Ac+CpTI pollen carried no lethal risk in honey bees. However, during a 7-day oral exposure to treated pollens without sugar provided, honey bees consumed less Cry1Ac+CpTI pollen compared with that of the control, which may indicated an antifeedant effect of honey bees on Cry1Ac+CpTI pollen. This is the first report suggesting an antifeedant effects of this cultivar pollen on honey bees.