LLH Bee Institute, Erlenstr. 9, 35274, Kirchhain, Germany.
Dipartimento di Scienze e Tecnologie Agro-Alimentari, Università di Bologna, Bologna, Italy.
Sci Rep. 2020 Mar 13;10(1):4670. doi: 10.1038/s41598-020-61445-w.
Solitary bees are frequently exposed to pesticides, which are considered as one of the main stress factors that may lead to population declines. A strong immune defence is vital for the fitness of bees. However, the immune system can be weakened by environmental factors that may render bees more vulnerable to parasites and pathogens. Here we demonstrate for the first time that field-realistic concentrations of the commonly used neonicotinoid insecticide thiacloprid can severely affect the immunocompetence of Osmia bicornis. In detail, males exposed to thiacloprid solutions of 200 and 555 µg/kg showed a reduction in hemocyte density. Moreover, functional aspects of the immune defence - the antimicrobial activity of the hemolymph - were impaired in males. In females, however, only a concentration of 555 µg/kg elicited similar immunosuppressive effects. Although males are smaller than females, they consumed more food solution. This leads to a 2.77 times higher exposure in males, probably explaining the different concentration thresholds observed between the sexes. In contrast to honeybees, dietary exposure to thiacloprid did not affect melanisation or wound healing in O. bicornis. Our results demonstrate that neonicotinoid insecticides can negatively affect the immunocompetence of O. bicornis, possibly leading to an impaired disease resistance capacity.
独居蜜蜂经常接触到农药，这被认为是导致种群数量下降的主要压力因素之一。强大的免疫防御对于蜜蜂的健康至关重要。然而，环境因素会削弱免疫系统，使蜜蜂更容易受到寄生虫和病原体的侵害。在这里，我们首次证明，田间实际浓度的常用新烟碱类杀虫剂噻虫啉会严重影响二色壁蜂的免疫能力。具体来说，暴露于 200 和 555μg/kg 噻虫啉溶液中的雄性蜜蜂的血淋巴密度降低。此外，免疫防御的功能方面——血淋巴的抗菌活性——在雄性中受到损害。然而，只有 555μg/kg 的浓度才会对雌性产生类似的免疫抑制作用。尽管雄性比雌性小，但它们消耗了更多的食物溶液。这导致雄性的暴露量增加了 2.77 倍，这可能解释了两性之间观察到的不同浓度阈值。与蜜蜂不同的是，饮食中接触噻虫啉不会影响二色壁蜂的黑化或伤口愈合。我们的研究结果表明，新烟碱类杀虫剂会对二色壁蜂的免疫能力产生负面影响，可能导致其疾病抵抗力下降。
