Risk Assessment Of Transgenic (CrylAc+CpTI) Cotton On The Honey Bee Apis Mellifera L.

The potential risk of transgenic Bt(Bacillus thuringiensis) cotton on non-target insects is an important part of ecological risk assessment. In this study, transgenic Cry Ac (Bt insecticidal endotoxin) plus CpTI (Cowpea trypsin inhibitor) cotton cultivar CCRI41 was used as experimental cotton variety and honey bees Apis mellifera L. as surrogate insects. On the one hand, the expression levels of the endotoxins Cry 1 Ac and CpTI in CCRI41 pollen were measured throughout the entire season. On the other hand, risk assessment of this cotton cultuvar pollen on A. mellifera was conducted using laboratory bio-assay procotols. The potential lethal effect and sublethal effect posed by this transgenic cultivar on worker bees including feeding behavior, olfactory learning performance, visual learning performance were examined. The aim of this study was to accumulate sciencific data for risk assessment of CCRI41 and provide scientific basis for the framework of Apis mellifera conservation. The results were as follows:1) ELISA quantitative detection for proteins CrylAc and CpTI in CCRI41 pollenThe content of CrylAc and CpTI in CCRI41 pollen were quantified using ELISA detection. Results indicated a high variability in levels of CrylAc among samples colleacted in different dates. The peak of Cry Ac expression was obtained in pollen from mid-stage bloom,300±4.52ng.g-1. CpTI protein was detectable but the levels were low.2) Lethal effectUsing laboratory feeding bio-assay, aritificial food contraining conventional cotton pollen (CCRI23), CCRI41 cotton pollen and imidacloprid-conta minsated conventional pollen were formulated as three different oral-feeding treatments. The honey bee mortality was recorded each day during 7-day oral chronic exposure. Results showed no significant higher mortality in honey bees in CCRI41-exposed treatment than the control group. It was indicated that no lethal effect was identified regarding CCRI41 pollen on honey bees.3) Sublethal effect:feeding behaviorUsing laboratory feeding bio-assay, consumption of artifical food containing pollen was recorded daily to obtain the mean daily quantity of food consumed per honey bee and mean total quantity of food consumed per honey bee during the 7-day oral chronic exposure in different treatments. The results indicated that honey bees tend to consume less and less food over the course of the experiment in all treatments, however, it was marginally significant. That is, daily consumption of food differed significantly among food types with honey bee consu minsg significantly more conventional pollen (control) than CCRI41 pollen and imidacloprid-conta minsated pollen. Regarding total consumption of food in 7 days, the same results were obtained. It can be tentatively concluded that CCRI41 pollen may carry an antifeedant effect on worker Apis mellifera. This conclution deserved further study and verification.4) Sublethal effect:visual learning performanceAfter assessment of feeding behavior in honey bees, T-maze model was designed to evaluate visual learning capacity of honey bees from different treatments. The results suggested that the visual learning capacity of honey bees from CCRI41 pollen treated group was not induced significantly compared to the coutrol group, and CCRI41 pollen exposed honey bee showed a strong visual learning capacity in T-tube maze. However, notably, imidacloprid-exposed honey bees demonstrated a significantly lower visual learning capacity compared to those from the contol group. In conclusion, the extensive growth of CCRI41 cotton may not affect the visual learning and navigation in honey bees in the wild whereas the potential negative impact of imidacloprid on honey bees deserved more attention.5) Sublethal effect:olfactory learning performanceAfter assessment of visual learning performance in honey bees, PER (probosic extension response) model was developed for evaluation of olfactory learning capacity in honey bees from different treatments. The results suggested that the olfactory learning capacity of honey bees from CCRI41 pollen treated group was not induced significantly compared to the coutrol group, and CCRI41 pollen exposed honey bee showed a strong olfactory learning capacity during the PER. Nevertheless, notably, imidacloprid-exposed honey bees demonstrated a significantly lower olfactory learning capacity compared to those from the contol group. In conclusion, the extensive growth of CCRI41 cotton may not affect the olfaction identification and foraging efficiency in honey bees in the wild whereas the potential negative impact of imidacloprid on honey bees deserved more attention. This research focus on the systemic risk assessment of transgenic CryAc+CpTI cotton on honey bee A. mellifera, which provides important clues for the ecological risk assessment of transgenic crops since more and more transgenic plants are implemented thoughout the world. In agroecosystems, on the one hand, this study aims at accumulating sciencific data for ecological risk assessment of CCRI41 cotton and elicitting warning for its side effect on agroecosystems induced by its wide-spresd growing. On the other hand, the potential external factors which affect the survival and learning porformance of the honey bee population are tentatively discussed.