草地贪夜蛾幼虫对三种拒食剂的味觉电生理和取食行为反应

Gustatory electrophysiological and behavioral responses of Spodoptera frugiperda(Lepidoptera:Noctuidae)larvae to three plant secondary metabolites

【目的】探究草地贪夜蛾Spodopterafrugiperda幼虫对3种植物次生代谢物质苦参碱、印楝素和鱼滕酮的味觉电生理反应和取食行为,为利用植物源物质防控草地贪夜蛾提供理论依据。【方法】分别利用单感受器记录技术和二项叶碟法测定草地贪夜蛾幼虫对苦参碱、印楝素和鱼滕酮的味觉电生理反应和取食选择行为。利用浸叶法测定了3种植物次生代谢物质的化学制剂对草地贪夜蛾1龄、2龄和3龄幼虫的致死作用。【结果】草地贪夜蛾幼虫口器下颚外颚叶上的味觉中栓锥感器内存在对鱼滕酮敏感的味觉受体神经元,侧栓椎感器内存在对印楝素和苦参碱敏感的味觉受体神经元;苦参碱、印楝素以及鱼滕酮均能够显著抑制幼虫的取食选择行为;其中,印楝素抑制草地贪夜蛾幼虫取食选择行为的阈值浓度最低。3种植物次生代谢物质的化学制剂均能够对草地贪夜蛾幼虫产生有效的致死作用。如6.0%鱼滕酮和0.3%印楝素稀释120倍时,对草地贪夜蛾1龄幼虫的致死率分别为100%和74.3%。【结论】3种植物次生代谢物质均能够对草地贪夜蛾幼虫的取食产生拒食作用,其拒食作用的趋势与幼虫味觉受体神经元对这些物质的反应趋势一致。3种植物次生代谢物质的相应制剂均能对草地贪夜蛾幼虫产生明显的致死作用。

[Objectives]To determine the gustatory electrophysiological and behavioral responses of the fall armyworm Spodoptera frugiperda to three plant secondary metabolites;rotenone,azadirachtin and matrine,and thereby provide a basis for the environmentally-friendly control of this important pest.[Methods]Gustatory electrophysiological responses were measured by single sensillum recording whereas behavioral responses were determined using a dual-leaf-disc choice assay.In addition,the leaf-dipping method was used to investigate the lethality of the three plant secondary metabolites to first,second and third instar larvae.[Results]The medial sensillum styloconicum on the maxillary galea of S.frugiperda caterpillars ha a gustatory receptor neuron(GRN)sensitive to rotenone,whereas the lateral sensillum on the maxillary galea has GRNs sensitive to matrine and azadirachtin.Certain concentrations of rotenone,azadirachtin and matrine inhibited feeding by larvae with azadirachtin having the strongest inhibitory effect,inhibiting feeding even at relatively low concentrations.Chemical agents of the three plant secondary metabolites had significant lethal effects on larvae;6.0%rotenone and 0.3%azadirachtin(120 dilution ratio)caused 100%and 74.3%,respectively,mortality in first instar larvae.[Conclusion]The plant secondary metabolites rotenone,azadirachtin and matrine,clearly suppress feeding by S.frugiperda larvae.This is consistent with the gustatory responses of the GRNs of larvae to these compounds,and their high lethality to first instar S.frugiperda larvae.