Abstract：
Public concern about the effects of pesticides on non-target organisms has increased in the recent years. Nevertheless, there is a limited number of studies that address the actual toxic effects of herbicides on insects. This study investigated the side effects of herbicides on non-target organisms inhabiting agroecosystems and performing essential ecological and economic functions such as crop pollination. We analysed morphological alterations in the gut, Malpighian tubules and circulating haemocytes of Apis mellifera workers as markers of exposure effects. A commercial formulation of a pendimethalin-based herbicide (PND) was administered orally under laboratory conditions at a realistic concentration admitted in the field (330gL-1 of active ingredient., 4 L ha-1 for cereal and vegetable crops). The worker bees were exposed to a single application of PND for a period of one week, to simulate the exposure that can occur when foraging bees accidentally drink drops of contaminated water upon treatments. Histopathological analyses of the midgut, ileum and Malpighian tubules showed alterations over time (from 24 to 72 h after the beginning of exposure) such as loss of epithelial organisation, cellular vacuolisation and altered pyknotic nuclei as well as disruption of the peritrophic membrane over time. Semiquantitative analyses of the midgut showed a significant increase in the organ injury index 24 and 72 h after the initial exposure in PND-exposed bees compared to control bees. In addition, a change in positivity to Gram staining was observed in the midgut histological sections. A recovery of cytotoxic effects was observed one week after the initial exposure, which was favoured by the periodic renewal of the intestinal epithelium and the herbicide dissipation time. Cytochemical staining with Giemsa of haemocytes from PND-treated workers over 24 and 72 h showed significant nuclear alterations such as lobed or polymorphic nuclei and micronuclei compared to bees in the control group. These results show that the dose of PND used to protect crops from weeds can lead to significant cytotoxic and genotoxic effects in non-target organisms such as honey bees. In croplands, the sublethal effects on cell morphology can impair vital physiological processes such as nutrition, osmoregulation, and resistance to pathogens, contributing to the decline in biodiversity and abundance of species that play a prominent ecological role, such as pollinators.
摘要：
近年来，公众对农药对非目标生物的影响的关注有所增加。然而，关于除草剂对昆虫的实际毒性作用的研究数量有限。这项研究调查了除草剂对居住在农业生态系统中并执行诸如作物授粉之类的基本生态和经济功能的非目标生物的副作用。我们分析了肠道的形态学改变，Apismellifera工人的Malpighian小管和循环血细胞作为暴露效果的标志。在实验室条件下，以现场允许的实际浓度（330gL-1活性成分）口服口服施用基于二甲戊灵的除草剂（PND）的商业制剂。,4Lha-1用于谷物和蔬菜作物)。工蜂暴露于一次PND应用一周，模拟当觅食蜜蜂在处理时不小心喝了受污染的水滴时可能发生的暴露。中肠的组织病理学分析，回肠和Malpighian小管随着时间的推移（从暴露开始后的24到72小时）显示出改变，例如上皮组织的丧失，随着时间的推移，细胞空泡化和收缩核的改变以及围食膜的破坏。中肠的半定量分析显示，与对照蜜蜂相比，暴露于PND的蜜蜂在初次暴露后24和72小时的器官损伤指数显着增加。此外,在中肠组织学切片中观察到革兰氏染色阳性的变化。首次暴露后一周观察到细胞毒性作用的恢复，肠上皮的周期性更新和除草剂消散时间有利于这一点。与对照组的蜜蜂相比，经过24小时和72小时的PND处理的工人的血细胞的Giemsa细胞化学染色显示出明显的核改变，例如叶状或多态性核和微核。这些结果表明,用于保护作物免受杂草侵害的PND的剂量可在非靶生物体如蜜蜂中导致显著的细胞毒性和基因毒性作用。在农田中，对细胞形态的亚致死效应会损害重要的生理过程，如营养，渗透调节，和对病原体的抗性，导致生物多样性和物种数量下降，这些物种起着重要的生态作用，如传粉者。
