Abstract：
The stingless bee Frieseomelitta varia Lepeletier 1836 (Hymenoptera: Apidae) is an essential pollinator in natural and agricultural ecosystems in the Neotropical region. However, these bees may be exposed to pesticides during foraging, which can affect both individuals and their colonies. One example comes from the use of pyraclostrobin (a fungicide) and thiamethoxam (an insecticide) for pest control in pepper crops, which F. varia visits. This study aimed to evaluate the isolated and combined sublethal effects of thiamethoxam (TMX) (0.000543 ng a.i./µL) and pyraclostrobin (PYR) (1.5 ng i.a./µL) on the morphology of the midgut and Malpighian tubules of F. varia workers. Results showed that both pesticides, regardless of the exposure time (through feeding during 48 h or 96 h), disturbed the morphology of the analyzed organs. Specifically, F. varia exposed orally to sublethal concentrations of thiamethoxam and pyraclostrobin, either alone or in combination, exhibited a higher rate of damage to the midgut (e.g., vacuolization, apocrine secretion, and cellular elimination) compared to the bees in the control groups, both after 48 h and 96 h of exposure. In Malpighian tubules, vacuolation is the only damage present. As the observed morphological alterations likely compromise the excretion and absorption functions, exposure to pyraclostrobin and thiamethoxam may lead to disturbances at both the individual and colony levels. These results highlight the urgent need for a future reassessment of the safety of fungicides and insecticides regarding their potential effects on bee populations.
摘要：
无刺蜜蜂FrieseomelittavariaLepeletier1836（膜翅目：Apidae）是新热带地区自然和农业生态系统中必不可少的传粉媒介。然而,这些蜜蜂在觅食过程中可能会接触杀虫剂，会影响个体和他们的殖民地。一个例子来自于在辣椒作物中使用吡唑醚酯(一种杀真菌剂)和噻虫嗪(一种杀虫剂)进行病虫害防治,F.varia访问。本研究旨在评估噻虫嗪（TMX）（0.000543nga.i./µL）和吡唑氯甾素（PYR）（1.5ngi.a./µL）对中肠和Malpighian小管形态的分离和联合亚致死作用。结果表明，两种农药，无论暴露时间如何（通过在48小时或96小时内喂食），扰乱了被分析器官的形态。具体来说,F.varia口服暴露于亚致死浓度的噻虫嗪和吡唑醚，无论是单独还是组合，表现出更高的中肠损伤率(例如，真空化,大汗腺分泌,和细胞消除）与对照组中的蜜蜂相比，暴露48小时和96小时后。在Malpighian小管中，空泡是唯一存在的损害。由于观察到的形态学改变可能会损害排泄和吸收功能，暴露于唑来醇酯和噻虫嗪可能会导致个体和菌落水平的干扰。这些结果突出表明，迫切需要对杀菌剂和杀虫剂对蜜蜂种群的潜在影响进行未来的安全性重新评估。
