红火蚁工蚁对棉蚜诱导的棉花挥发物的嗅觉和行为反应

【目的】红火蚁 Solenopsis invicta 与棉蚜 Aphis gossypii 存在兼性共生关系,红火蚁可能利用棉蚜危害诱导棉花释放的挥发物定位棉蚜。本研究将测试红火蚁工蚁对棉花挥发物的嗅觉和行为反应。【方法】使用Y型管实验测试红火蚁工蚁对棉花气味的行为反应;以红火蚁告警信息素2-乙基-3,5(6)-二甲基吡嗪为阳性对照,测试红火蚁工蚁对不同剂量(100, 10, 1 和0.1 μg)的9种棉花挥发物组分[α-蒎烯、β-蒎烯、β-石竹烯、( E, E )-4,8,12-三甲基-1,3,7,11-十三碳四烯(TMTT)、( E )-4,8-二甲基-1,3,7-壬三烯(DMNT)、辛醛、6-甲基-5-庚烯-2-酮、顺-3-己烯基乙酸酯和水杨酸甲酯]的触角电位反应;再利用Y型嗅觉仪测试这些挥发物对红火蚁工蚁的行为选择影响。【结果】结果表明,受棉蚜为害的棉花较健康棉花对红火蚁工蚁具有极显著的引诱效果。红火蚁对9种挥发物组分的EAG反应随着剂量升高而升高。各化合物在100 μg剂量时EAG反应值最大,其中,工蚁对水杨酸甲酯和6-甲基-5-庚烯-2-酮这两个化合物反应最强。在行为选择实验中,化合物水杨酸甲酯、6-甲基-5-庚烯-2-酮和DMNT对红火蚁工蚁均具有显著的引诱效果。【结论】棉蚜诱导的棉花挥发物中水杨酸甲酯和6-甲基-5-庚烯-2-酮对红火蚁有显著的引诱效果,这2种化合物可能在红火蚁定位棉蚜、建立共生关系中起着关键的作用。

Olfactory and behavioral responses of Solenopsis invicta (Hymenoptera: Formicidae) workers to cotton volatiles induced by cotton aphids

【Aim】 There is a facultative mutualistic interaction between the red imported fire ant, Solenopsis invicta and the cotton aphid, Aphis gossypii. Fire ants may utilize cotton aphid-induced cotton volatiles to locate mutualistic partners. This study aims to test the olfactory and behavioral responses of S. invicta workers to cotton volatiles induced by cotton aphid. 【Methods】 The behavioral response of S. invicta workers to cotton odor was tested by Y-tube. The electroantennogram (EAG) responses of the fire ant workers to nine volatile compounds including (1S)-(-)-α-pinene, (1S)-(-)-β-pinene, β-caryophyllene, (E, E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene (TMTT), (E)-4,8-dimethyl 1,3,7-nonatriene (DMNT), octanal, 6-methyl-5-hepten-2-one, (Z)-(3)-hexenyl acetate, and methyl salicylate at different dosages (100, 10, 1 and 0.1 μg) were tested using fire ant alarm pheromone 2-ethyl-3,5(6)-dimethylpyrazine as the positive control, and the influence of the volatile compounds on the behavior choice of the fire ant workers was tested by Y-tube olfactometer. 【Results】 The results showed that fire ant workers were significantly attracted to the cotton plants damaged by cotton aphids over undamaged ones. The EAG responses of fire ant workers to the nine volatile compounds were dose-dependent. These compounds triggered the highest EAG response in fire ant workers at the dose of 100 μg, and methyl salicylate and 6-methyl-5-hepten-2-one caused the greatest EAG responses. In behavioral selection experiments, fire ant workers were significantly attracted to methyl salicylate, 6-methyl-5-hepten-2-one and DMNT. 【Conclusion】 Among cotton aphid-induced volatile compounds, methyl salicylate and 6-methyl-5-hepten-2-one significantly attract fire ants, and they may play a key role in locating cotton aphids by fire ants for establishment of mutualistic interaction.