柑橘木虱蜜露排泄机制:进展与展望

半翅目昆虫柑橘木虱Diaphorina citri是柑橘类果树重要害虫,主要以高渗透压的植物韧皮部汁液为食,是柑橘毁灭性病害——柑橘黄龙病(HLB)的主要传播媒介。柑橘木虱取食韧皮部汁液时自身进化出一套完整的渗透调节机制调节其体内渗透压,将体内过量摄入的糖类转化成长链寡糖并以蜜露形式排出体外。本文从柑橘木虱蜜露排泄行为、蜜露组成成分以及影响蜜露排泄的多个因素进行了论述,同时综述了可能参与柑橘木虱蜜露排泄行为的渗透调节基因。研究表明,柑橘木虱雌雄成虫及若虫在蜜露排泄行为上存在显著差异,且排泄的蜜露在颜色、纹路及组成成分方面均有不同;寄主植物、杀虫剂、病原微生物及天敌化合物均会影响柑橘木虱蜜露排泄行为。分子机制探究发现,α-葡萄糖苷水解酶、水通道蛋白及糖基转移酶基因等关键渗透调节基因可能参与调控柑橘木虱蜜露排泄行为。本文可为未来有关柑橘木虱蜜露排泄行为方面的研究以及为研制柑橘木虱防治新型药剂开发新靶标提供参考。

Honeydew excretion mechanisms in the Asian citrus psyllid,Diaphorina citri(Hemiptera: Psyllidae): progress and prospects

The Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae), is a general pest causing economic losses in orchards, mainly feeds on the highly osmotic sap of citrus phloem and transmits pathogen Candidatus Liberibacter asiaticus to induce a devastating disease of citrus named huanglongbing (HLB). The osmotic pressure of phloem sap is a challenge for hemipteran insects, which is regulated by a set of osmoregulation mechanisms evolved in insects. The excessive sugars are converted into long chain oligosaccharides and excreted outside of insects as honeydew. In this article, the behavior of honeydew excretion, composition of honeydew and factors affecting honeydew excretion of D. citri are summarized, and the functions of osmoregulatory genes involved are overviewed. The studies show that the behavior of honeydew excretion and the color, texture and composition of honeydew were different among male and female adults and nymphs of D. citri. The host plants, insecticides, pathogenic microorganisms and compounds secreted by natural enemies were demonstrated as the main factors affecting the excretion behavior of D. citri. In addition, the pivotal osmoregulatory genes encoding α-glucoside hydrolases, aquaporins and sugar transporters were considered as the potential genes involved in the regulation of honeydew excretion. This review may provide a reference for further studying honeydew excretion behavior of D. citri and exploring the new targets for developing new insecticides for the control of this insect.