Huang Qingchun, Zhang Lei, Yang Chao, Yun Xinmin, He Yuan
Shanghai Key Lab of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China.
Shanghai Key Lab of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China.
Pestic Biochem Physiol. 2016 Jun;130:31-38. doi: 10.1016/j.pestbp.2015.12.003. Epub 2015 Dec 8.
Hemocytes circulating in the hemolymph are essential for the insect immunity to protect insects against infections. The effects of sublethal hexaflumuron exposure on the competence of hemocyte immunity of fifth-instar larvae of Mythimna separata were investigated. In this insect, the sublethal exposure could cause plasmatocyte filopodia to contract and shorten, and granulocytes to compact with a loss of cytoplasmic projections in vitro, and induce granulocytes to swell and expand in vivo. The mean number of total hemocytes was significantly declined in feed-thru larvae by 5.0μgmL(-1) hexaflumuron. Changes in proportional counts of hemocytes showed that sublethal hexaflumuron exposure caused a decrease of granulocytes and an increase of plasmatocytes in a concentration-dependant manner, but these changes were time-dependently reduced. Few effects of the sublethal exposure were revealed on the proportional counts of spherulocytes, oenocytoids, and prohemocytes. The exposure at 24h showed strong inhibition on phenoloxidase activity in plasma and hemocytes, but this inhibition was time-dependently weakened. The NADPH-diaphorase staining assays showed that a positive immune response of nitric oxide synthase (NOS) in hemocytes was incited by the sublethal exposure, and the longer-time exposure to the higher concentrations of hexaflumuron caused a heavier loss of NOS activity. Phagocytosis rates revealed the inhibitory effect of sublethal hexaflumuron exposure on the phagocytic ability of granulocytes and plasmatocytes that was significantly greater than the effect of chlorpyrifos at the same concentrations. These results show that sublethal hexaflumuron exposure reduces M. separata larval survival by depressing the competence of hemocyte-mediated immune responses.
血淋巴中循环的血细胞对于昆虫免疫至关重要，可保护昆虫免受感染。研究了亚致死剂量氟铃脲暴露对粘虫五龄幼虫血细胞免疫能力的影响。在这种昆虫中，亚致死暴露可导致体外血浆细胞丝状伪足收缩和缩短，粒细胞致密化并失去细胞质突起，体内可诱导粒细胞肿胀和扩张。通过5.0μgmL(-1)氟铃脲处理的经口摄入幼虫中，血细胞总数显著下降。血细胞比例计数的变化表明，亚致死剂量氟铃脲暴露导致粒细胞数量减少，血浆细胞数量呈浓度依赖性增加，但这些变化随时间而减少。亚致死暴露对球形细胞、绛色细胞和原血细胞的比例计数几乎没有影响。暴露24小时时，血浆和血细胞中的酚氧化酶活性受到强烈抑制，但这种抑制随时间而减弱。NADPH-黄递酶染色分析表明，亚致死暴露可激发血细胞中一氧化氮合酶（NOS）的阳性免疫反应，且长时间暴露于较高浓度的氟铃脲会导致NOS活性损失更严重。吞噬率显示，亚致死剂量氟铃脲暴露对粒细胞和血浆细胞吞噬能力的抑制作用明显大于相同浓度的毒死蜱。这些结果表明，亚致死剂量氟铃脲暴露通过抑制血细胞介导的免疫反应能力降低了粘虫幼虫的存活率。
