氟啶虫胺腈调控棉蚜繁殖的分子机制

Sulfoxaflor, the first sulfoximines insecticide, is an agonist at insect nicotinic acetylcholine receptors (nAChRs) and functions in a manner distinct from other insecticides acting at nAChRs. It has been widely used in the control of sucking insect pests including resistant Aphis gossypii. However, our early studies indicate sulfoxaflor significantly stimulate the reproduction of A. gossypii. The intrinsic rate of increase (rm), finite rate of increase (λ), net reproductive rate (R0) and mean fecundity of females were significantly increased by sulfoxaflor treatment, while the treatment decreased the mean generation time (T). Based on the previous study, the project will clone and express A. gossypii vitellogenin (AgVg) and vitellogenin receptor (AgVgR) genes in vitro, detect the specific regulation of sulfoxaflor on the relative expression and protein content of Agvg and AgVgR genes. In order to clarify how to experience the stimulation of insecticide and regulate the vitellogenesis in A. gossypii, the effects of sulfoxaflor on the insulin signaling pathway and the juvenile hormone signaling pathway will be studied. Besides, we will study the mechanism of sulfoxaflor on vitellogenesis, development of ovary and fecundity in susceptible and imidacloprid-resistant A. gossypii. The implementation of this project will clarify the molecular mechanism of sulfoxaflor stimulating the fecundity of A. gossypii, and will provide the theoretical foundation for the pest resistance management.

氟啶虫胺腈是第一个砜亚胺类杀虫剂，通过作用于昆虫烟碱型乙酰胆碱受体独特的结合位点而发挥杀虫作用，被广泛应用于抗性棉蚜等刺吸式口器害虫的综合防治。前期研究结果表明：氟啶虫胺腈对棉蚜的繁殖具有明显的刺激作用，存在诱导棉蚜再猖獗的风险。氟啶虫胺腈导致棉蚜种群生命表参数内禀增长率、周限增长率、净生殖率和总繁殖率显著升高，平均世代周期显著缩短。基于此，本项目拟克隆和表达棉蚜卵黄原蛋白和卵黄原蛋白受体基因，明确氟啶虫胺腈对棉蚜卵黄原蛋白和卵黄原蛋白受体基因表达量及蛋白含量的特异性调控；研究氟啶虫胺腈对棉蚜胰岛素信号通路和保幼激素信号通路的调控，阐明棉蚜感受氟啶虫胺腈刺激后调控卵黄原蛋白合成和卵黄蛋白积累的过程；进而研究氟啶虫胺腈对不同抗性品系棉蚜生殖力调控的机制；从而揭示氟啶虫胺腈调控棉蚜繁殖的分子机制，为更有效的开展棉蚜抗药性治理提供理论基础。

氟啶虫胺腈是第一个砜亚胺类杀虫剂，通过作用于昆虫烟碱型乙酰胆碱受体独特的结合位点而发挥杀虫作用，被广泛应用于抗性棉蚜等刺吸式口器害虫的综合防治。前期研究发现氟啶虫胺腈对棉蚜的繁殖具有明显的刺激作用，存在诱导棉蚜再猖獗的风险。基于此本项目研究了氟啶虫胺腈调控棉蚜繁殖的分子机制以及解毒代谢酶介导的棉蚜对氟啶虫胺腈的抗性机制。结果表明：与敏感（Sus）种群相比，氟啶虫胺腈抗性（Sul-R）种群棉蚜繁殖力显著升高，相对适合度为1.19；Sul-R棉蚜卵黄原蛋白（Vg）和卵黄原蛋白受体（VgR）基因表达量（2.5倍和1.38倍）及蛋白含量（1.3倍和1.73倍）较Sus种群显著升高；LC10剂量的氟啶虫胺腈处理F0代棉蚜可诱导其子代Vg和VgR基因的上调表达和蛋白含量的升高；沉默Vg和VgR基因的表达显著降低了棉蚜的繁殖能力（分别为对照的0.47倍和0.42倍）。此外，LC10剂量的氟啶虫胺腈处理F0代敏感棉蚜能够诱导F1代棉蚜的增殖（1.10倍）；而且氟啶虫胺腈诱导棉蚜取食活动更活跃，低剂量的氟啶虫胺腈可延长Sul-R种群（1.45倍）和Sus种群（1.44倍）棉蚜在韧皮部中的持续取食时间。研究结果表明25个P450基因、11个UGT基因和10个ABC转运蛋白基因表达量在Sul-R棉蚜种群中显著上调，上调倍数分别为1.15倍-4.89倍、1.41-5.46倍和1.66-3.25倍。利用RNAi沉默和Sf9细胞表达，证明了CYP6CY13-2、UGT350A2、UGT351A4、UGT350B2、UGT343C2、ABCA1和ABCD1的高表达介导了棉蚜对氟啶虫胺腈的抗性机制。本研究揭示了氟啶虫胺腈调控棉蚜繁殖的分子机制及棉蚜对氟啶虫胺腈的抗性机制，此结果为更有效的开展棉蚜抗药性治理提供理论基础。