The weight of the evidence suggests bt corn pollen in the field does not pose a hazard to monarch larvae concludes epa scientist zigfridas vaituzis who heads the agency ' s team studying the ecological effects of bt crops 环保署bt作物环境评估小组的负责人卫图吉斯总结道: “现有证据意味着,田野里的bt玉米花粉不会威胁大桦斑蝶幼虫的生存。 ”