Department of Biology, Ecology and Earth Science, University of Calabria, Italy.
Department of Life Sciences, University of Trieste, Italy.
J Insect Physiol. 2021 May-Jun;131:104236. doi: 10.1016/j.jinsphys.2021.104236. Epub 2021 Apr 6.
Herbicides have become the most commonly applied agrochemicals in agroecosystems. Thus, basic knowledge of their physiological effects on insects is needed, especially for understanding their impact on beneficial insect species. In this study, we evaluated the effect of a pendimethalin-based herbicide (PND) on the cellular immune response of the carabid beetle Harpalus (Pseudoophonus) rufipes (De Geer 1774) (Coleoptera, Carabidae), acting as biocontrol agent in agroecosystems. Total and differential haemocyte counts and phagocytosis assay, performed by injecting in vivo carboxylate-modified polystyrene latex beads, were measured in beetles exposed to a recommended field dose (4L per ha) of PND to evaluate the exposure effects over the time. The pattern of haemocyte subpopulations and the decrease of the phagocytic index after the exposure to PND suggested a lowering of P. rufipes ability to face an infection performing a cell-mediated response. PND was also found to cause cytotoxic effects on the haemocyte ultrastructure. Ultrastructural alterations such as irregular shape, large vacuolization of the cytoplasm, and condensation of marginated chromatin were recorded from 2d of exposure. The loss of RER, Golgi apparatus, mitochondria integrity and the swelling of the outer nuclear membrane found in some haemocytes suggested an interference of PND with the membrane permeability. Results indicated that the exposure to PND impairs the distribution, morphology and physiological functions of haemocytes causing a decrease of P. rufipes immunocompetence. Moreover, the sensitivity to herbicide exposure makes this species a suitable model and a useful bioindicator for monitoring exposure effects on non-target species. This study provides useful information to protect and preserve biodiversity of insects in agroecosystems.
除草剂已成为农业生态系统中应用最广泛的农用化学品。因此，需要了解它们对昆虫的生理影响，特别是为了了解它们对有益昆虫物种的影响。在这项研究中，我们评估了一种基于二甲戊灵的除草剂（PND）对拟步甲（Pseudoophonus）rufipes（De Geer 1774）（鞘翅目，步甲科）细胞免疫反应的影响，拟步甲作为农业生态系统中的生物防治剂。通过体内注射羧基修饰聚苯乙烯乳胶珠，进行总血细胞和差异血细胞计数和吞噬作用测定，以评估在推荐田间剂量（每公顷 4L）暴露于 PND 的甲虫中随时间的暴露效应。暴露于 PND 后血细胞亚群的模式和吞噬指数的下降表明，拟步甲在进行细胞介导反应时面对感染的能力下降。PND 还被发现对血细胞的超微结构具有细胞毒性作用。从暴露的第 2 天开始，记录到不规则形状、细胞质大空泡化和边缘染色质凝聚等超微结构改变。一些血细胞中内质网、高尔基体、线粒体完整性的丧失和外核膜的肿胀表明 PND 干扰了膜通透性。结果表明，暴露于 PND 会损害血细胞的分布、形态和生理功能，导致拟步甲免疫能力下降。此外，对除草剂暴露的敏感性使该物种成为监测非靶标物种暴露效应的合适模型和有用的生物指示剂。本研究为保护和维护农业生态系统中昆虫的生物多样性提供了有用的信息。
