Centro de Estudos de Insetos Sociais, Departamento de Biologia, Instituto de Biociências de Rio Claro, UNESP-Univ., Estadual Paulista, Av. 24A, 1515, Bela Vista, 13.500-900 Rio Claro São Paulo, Brazil.
Environ Toxicol. 2014 Oct;29(10):1122-33. doi: 10.1002/tox.21842. Epub 2013 Jan 22.
The development of agricultural activities coincides with the increased use of pesticides to control pests, which can also be harmful to nontarget insects such as bees. Thus, the goal of this work was assess the toxic effects of thiamethoxam on newly emerged worker bees of Apis mellifera (africanized honeybee-AHB). Initially, we determined that the lethal concentration 50 (LC50 ) of thiamethoxam was 4.28 ng a.i./μL of diet. To determine the lethal time 50 (LT50 ), a survival assay was conducted using diets containing sublethal doses of thiamethoxam equal to 1/10 and 1/100 of the LC50. The group of bees exposed to 1/10 of the LC50 had a 41.2% reduction of lifespan. When AHB samples were analyzed by morphological technique we found the presence of condensed cells in the mushroom bodies and optical lobes in exposed honeybees. Through Xylidine Ponceau technique, we found cells which stained more intensely in groups exposed to thiamethoxam. The digestive and regenerative cells of the midgut from exposed bees also showed morphological and histochemical alterations, like cytoplasm vacuolization, increased apocrine secretion and increased cell elimination. Thus, intoxication with a sublethal doses of thiamethoxam can cause impairment in the brain and midgut of AHB and contribute to the honeybee lifespan reduction.
农业活动的发展伴随着杀虫剂使用的增加，以控制害虫，但这也可能对非靶标昆虫如蜜蜂造成危害。因此，这项工作的目的是评估噻虫嗪对新出现的非洲化蜜蜂（AHB）工蜂的毒性作用。最初，我们确定噻虫嗪的半数致死浓度（LC50）为 4.28ng a.i./μL 饮食。为了确定半数致死时间（LT50），我们使用含有亚致死剂量噻虫嗪的饮食进行了生存测定，其剂量分别等于 LC50 的 1/10 和 1/100。暴露于 LC50 的 1/10 的蜜蜂的寿命减少了 41.2%。当用形态学技术分析 AHB 样本时，我们发现暴露的蜜蜂的蘑菇体和视叶中有浓缩细胞。通过木精品红 Ponceau 技术，我们发现暴露于噻虫嗪的组中的细胞染色更深。暴露于噻虫嗪的蜜蜂的中肠的消化和再生细胞也表现出形态和组织化学改变，如细胞质空泡化、顶浆分泌增加和细胞消除增加。因此，亚致死剂量的噻虫嗪中毒会导致 AHB 大脑和中肠受损，并导致蜜蜂寿命缩短。
