Paula Débora P, Andow David A, Bellinati André, Timbó Renata Velozo, Souza Lucas M, Pires Carmen S S, Sujii Edison R
Embrapa Genetic Resources and Biotechnology, Parque Estação Biológica, W5 Norte, P.O. Box 02372, Brasília, DF, 70770-917, Brazil.
Department of Entomology, University of Minnesota, 219 Hodson Hall, 1980 Folwell Ave., St. Paul, MN, 55108, USA.
Ecotoxicology. 2016 Apr;25(3):601-7. doi: 10.1007/s10646-016-1619-9. Epub 2016 Feb 4.
Dose-response assays and surrogate species are standard methods for risk analysis for environmental chemicals. These assume that individuals within a species have unimodal responses and that a surrogate species can predict responses of other related taxa. We exposed immature individuals of closely related aphidophagous coccinellid predators, Cycloneda sanguinea and Harmonia axyridis, to Cry1Ac and Cry1F toxins through uniform and constant artificial tritrophic exposure through Myzus persicae aphids. Both toxins were detected in coccinellid pupae, with individual and interspecific variation. Uptake was significantly higher in H. axyridis than in C. sanguinea, both in the proportion of individuals and the concentrations per individual. We also observed bimodal uptake of the Cry toxins by H. axyridis, which indicated that some individuals had low bioaccumulation and some had high bioaccumulation. This suggests that standard dose-response assays need to be interpreted with caution and future assays should examine the modality of the responses. In addition, the similarity in the biological effects of the Cry toxins in the two predators was due to different biological exposure mechanisms. The majority of H. axyridis were exposed both internally and in the gut, while C. sanguinea was exposed primarily in the gut. Thus, despite their close phylogenetic relatedness, these species would not be good surrogates for each other and the surrogate species methodology should be tested more rigorously.
剂量反应测定和替代物种是环境化学品风险分析的标准方法。这些方法假定一个物种内的个体具有单峰反应，并且一个替代物种可以预测其他相关分类群的反应。我们通过桃蚜对密切相关的食蚜瓢虫捕食者——血色丽瓢虫和异色瓢虫的未成熟个体进行统一且恒定的人工三营养级暴露，使其接触Cry1Ac和Cry1F毒素。在瓢虫蛹中检测到了这两种毒素，存在个体差异和种间差异。无论是个体比例还是个体浓度，异色瓢虫的摄取量都显著高于血色丽瓢虫。我们还观察到异色瓢虫对Cry毒素的双峰摄取，这表明一些个体生物积累量低，而一些个体生物积累量高。这表明标准剂量反应测定需要谨慎解读，未来的测定应检查反应的模式。此外，两种捕食者中Cry毒素生物效应的相似性是由于不同的生物暴露机制。大多数异色瓢虫在体内和肠道都有暴露，而血色丽瓢虫主要在肠道有暴露。因此，尽管它们在系统发育上关系密切，但这些物种彼此之间并不是很好的替代物种，替代物种方法应该更严格地进行测试。
