草地贪夜蛾幼虫对四种刺激物质的味觉感受和取食选择

Gustatory perception and feeding preference of Spodoptera frugiperda(Lepidoptera:Noctuidae)larvae to four stimuli

【目的】为了筛选有效的草地贪夜蛾Spodoptera frugiperda幼虫取食激食素和抑制剂并探究其味觉感受机理,为生态防治草地贪夜蛾提供理论和实践上的依据。【方法】利用单感受器记录法测定草地贪夜蛾5龄第2天幼虫下颚外颚叶上中栓锥感器和侧栓锥感器对不同浓度的蔗糖、黑芥子苷、单宁酸和盐酸奎宁4种刺激物质的电生理反应,并采用二项叶碟法测定草地贪夜蛾幼虫对这些刺激物质的取食选择行为。【结果】草地贪夜蛾幼虫中栓锥感器和侧栓锥感器内均存在对蔗糖、黑芥子苷和单宁酸敏感的味觉受体神经元,但是神经元的活性随着刺激物的种类及浓度而变化。其中,两类感器内神经元对蔗糖和黑芥子苷的反应均呈现典型的浓度梯度反应。中栓锥感器内存在对盐酸奎宁敏感的味觉受体神经元,但是呈现逆浓度梯度的反应模式,侧栓锥感器内不存在对盐酸奎宁敏感的神经元。蔗糖显著诱导幼虫的取食行为,而盐酸奎宁、黑芥子苷和单宁酸均抑制幼虫的取食行为,且都呈现浓度梯度的抑制活性。【结论】草地贪夜蛾幼虫中栓锥感器和侧栓锥感器内均存在对取食激食素和抑制剂敏感的味觉受体神经元,但是两类感器不论在反应谱上还是敏感性上均存在差异。蔗糖可以作为取食激食素,盐酸奎宁、黑芥子苷和单宁酸可以作为取食抑制剂的有效候选物质。幼虫对蔗糖、黑芥子苷和单宁酸的味觉反应在一定程度上解释了其取食选择行为的味觉基础。本研究为草地贪夜蛾的生态防治提供了味觉信息。

【Aim】The aim of this study is to screen effective phagostimulants and deterrents,and to explore the gustatory perception mechanism of Spodoptera frugiperda larvae,so as to provide theoretical and practical references for the ecological control of the pest.【Methods】The single sensillum recording technique was used to investigate the electrophysiological characteristics of the medial sensillum styloconicum and the lateral sensillum styloconicum located on the maxillary galea of mouthparts of the day-25th instar larvae to four stimuli of sucrose,sinigrin,tannic acid,and quinine hydrochloride at different concentrations.The two-choice feeding assay was used to investigate the feeding choice of S.frugiperda larvae to these stimuli.【Results】Both the medial sensillum styloconicum and the lateral sensillum styloconicum of S.frugiperda larvae consist of gustatory receptor neurons sensitive to sucrose,sinigrin and tannic,with the responding activities of neurons changing based on stimuli and concentrations.However,the quinine hydrochloride only elicited electrophysiological responses of the medial sensillum styloconicum but not the lateral sensillum styloconicum.The responses of gustatory receptor neurons in both the medial and lateral sensilla styloconica to sucrose and sinigrin showed typical dose-dependent patterns,while the response of quinine hydrochloride to the medial sensillum styloconicum showed a reverse dose-dependent pattern.The results of behavioral choice showed that sucrose significantly induced the feeding choice of S.frugiperda larvae,while sinigrin,tannic and quinine hydrochloride inhibited their feeding choice in a dose-dependent pattern.【Conclusion】Gustatory receptor neurons housed in both the medial and lateral sensilla styloconica of S.frugiperda larvae respond to phagostimulants and deterrents.The two types of sensilla demonstrate different responding patterns in response spectrum and responding activities.Sucrose can be regarded as one candidate compound of phagostimulants,while quinine hydrochloride,sinigrin and tannic acid can be regarded as the candidate compounds of deterrents.The gustatory responding profiles of larvae may contribute to determining their feeding preference for these compounds.This study provides gustatory information for the ecological control of S.frugiperda.