PDF(Pubmed)
Abstract：
Melipona scutellaris is a Brazilian stingless bee that is important for pollinating wild flora and agriculture crops. Fungicides have been widely used in agriculture, and floral residues can affect forager bees. The goal of our study was to evaluate the effects of sublethal concentrations of pyraclostrobin on the midgut ultrastructure of M. scutellaris forager workers. The bees were collected from three non-parental colonies and kept under laboratory conditions. The bees were orally exposed continuously for five days to pyraclostrobin in syrup at concentrations of 0.125 ng a.i./µL (FG1) and 0.005 ng a.i./µL (FG2). The control bees (CTL) were fed a no-fungicide sucrose solution, and the acetone solvent control bees (CAC) received a sucrose solution containing acetone. At the end of the exposure, the midguts were sampled, fixed in Karnovsky solution, and routinely processed for transmission electron microscopy. Ultrastructural analysis demonstrated that both the fungicide concentrations altered the midgut, such as cytoplasmic vacuolization (more intense in FG1), the presence of an atypical nuclear morphology, and slightly dilated mitochondrial cristae in the bees from the FG1 and FG2 groups (both more intense in FG1). Additionally, there was an alteration in the ultrastructure of the spherocrystals (FG1), which could be the result of cellular metabolism impairment and the excretion of toxic metabolites in the digestive cells as a response to fungicide exposure. The results indicate that ingested pyraclostrobin induced cytotoxic effects in the midgut of native stingless bees. These cellular ultrastructural responses of the midgut are a prelude to a reduced survival rate, as observed in previous studies.
摘要：
Meliponascutellaris是巴西无刺蜜蜂，对于为野生动植物和农作物授粉很重要。杀菌剂已广泛用于农业,花的残留物会影响觅食蜜蜂。我们研究的目的是评估亚致死浓度的吡唑酮醇酯对黄藻虫觅食工人中肠超微结构的影响。从三个非亲本菌落收集蜜蜂并保持在实验室条件下。将蜜蜂连续5天口服暴露于浓度为0.125nga.i./µL（FG1）和0.005nga.i./µL（FG2）的吡唑醇酯糖浆中。对照蜜蜂（CTL）饲喂非杀真菌剂蔗糖溶液，丙酮溶剂对照蜜蜂(CAC)接受含有丙酮的蔗糖溶液。曝光结束时,内脏被取样，固定在Karnovsky解决方案中，并进行常规处理以进行透射电子显微镜检查。超微结构分析表明，两种杀菌剂浓度都改变了中肠，例如细胞质空泡化（在FG1中更强烈），非典型核形态的存在，来自FG1和FG2组的蜜蜂中的线粒体cr略有扩张（在FG1中均更强烈）。此外,球晶（FG1）的超微结构发生了变化，这可能是细胞代谢受损和消化细胞中有毒代谢物排泄的结果，作为对杀菌剂暴露的反应。结果表明，摄入的pyracraclostrobin在天然无刺蜜蜂的中肠中诱导了细胞毒性作用。中肠的这些细胞超微结构反应是降低存活率的前奏，正如在以前的研究中观察到的那样。
