Comparative immunotoxicity of bees, apis mellifera (hymenoptera: apidae), exposed to natural and synthetic xenobiotics

The objective of this study was to compare the effects of natural and synthetic chemical pesticides, thereby examining the supposed selectivity of these natural compounds on Apis mellifera bees. The LC50 values used in the bioassays were obtained from the research by Souza et al. (2023) and are as follows: Karate® (13.4 µL/100 mL), Limonene compound (1,440 µL/100 mL), and Roundup® (712,290 µL/100 mL). However, as reported by these authors, a concentration of 250 µL/100 ml was used for Azamax®. These LC50 values, along with a concentration of 250 µL/100 mL of Azamax®, were employed in immunohistochemical analyzes using the TUNEL method and PCNA in the midgut of bees. Immunological assessments (nitric oxide, phenoloxidase, and oxidative stress markers TBARS and GSH) were also conducted on adult worker bees. The xenobiotic treatments did not reveal apoptosis or cell proliferation. Nonetheless, we observed epithelial degeneration, marked by the presence of vacuolated cells, suggesting a necrotic process. Except for the Limonene compound, all substances induced oxidative stress, leading to increased levels of TBARS. Although there were no differences in GSH levels, we observed alterations in the immune system of these insects, characterized by increased phenoloxidase activity and NO2 levels. Based on the acquired results, it is possible to conclude that caution should be exercised when using chemical pesticides in agriculture, whether they are of synthetic or natural origin, as they have the potential to cause irreversible histopathological and immunological damage. This study also underscores the importance of conducting more comprehensive investigations into the impact of natural products on the physiology of pollinator insects.

本研究旨在比较天然与合成化学农药的效应，进而探究这些天然化合物对西方蜜蜂（Apis mellifera）的假定选择性。本研究采用的生物测定半数致死浓度（LC50, Lethal Concentration 50）值源自Souza等人（2023）的研究，具体如下：功夫菊酯（Karate®）：13.4 µL/100 mL，柠檬烯类化合物：1440 µL/100 mL，农达（Roundup®）：712290 µL/100 mL。然而，如这些作者所述，本研究中阿扎麦克斯（Azamax®）采用的浓度为250 µL/100 mL。上述LC50值与250 µL/100 mL的阿扎麦克斯（Azamax®）浓度，被用于针对蜜蜂中肠的免疫组化分析，检测方法包括脱氧核糖核苷酸末端转移酶介导的缺口末端标记法（TUNEL, Terminal deoxynucleotidyl transferase dUTP Nick End Labeling）与增殖细胞核抗原（PCNA, Proliferating Cell Nuclear Antigen）。本研究还对成年工蜂开展了免疫学评估，检测指标包括一氧化氮（nitric oxide）、酚氧化酶（phenoloxidase），以及氧化应激标志物硫代巴比妥酸反应物（TBARS, Thiobarbituric Acid Reactive Substances）与谷胱甘肽（GSH, Glutathione）。外源化合物处理未检测到细胞凋亡或细胞增殖现象。但研究观察到上皮细胞变性，以空泡化细胞的出现为特征，提示存在坏死进程。除柠檬烯类化合物外，其余所有供试物质均会诱导氧化应激，导致TBARS水平升高。尽管谷胱甘肽（GSH）水平未出现显著变化，但研究观察到受试昆虫的免疫系统发生改变，具体表现为酚氧化酶活性与亚硝酸盐（NO2）水平升高。基于本研究所得结果，可得出如下结论：在农业生产中使用化学农药时需保持谨慎，无论其为合成来源还是天然来源，因为这类农药均有可能造成不可逆的组织病理学与免疫学损伤。本研究同时强调，有必要开展更为全面的调查，以探究天然产物对传粉昆虫生理机能的影响。