脂肪酸对红火蚁搬尸行为的影响

【目的】工蚁死亡后易受病原菌的侵染，进而危害蚁巢的健康。为了避免病菌横向传播，活工蚁根据尸体体内特定的化学物质的变化来识别尸体并将其搬运到弃尸堆。本实验旨在研究6种脂肪酸(油酸、亚油酸、棕榈油酸、棕榈酸、硬脂酸和肉豆蔻酸)对红火蚁Solenopsis invicta工蚁搬尸行为的影响，明确不同脂肪酸在其搬尸行为中发挥的作用。【方法】本实验利用GC-MS分析了工蚁活体和尸体提取物的脂肪酸成分，并在室内用滤纸片法测定了红火蚁对6种脂肪酸(10 μg/μL)、不同浓度(0.75和3 μg/μL)的单组分油酸或亚油酸以及不同浓度(0.01, 0.1, 1和10 μg/μL)的这两种酸的混合液的反应。【结果】结果表明，红火蚁尸体仅含有亚油酸和油酸两种脂肪酸；另外4种脂肪酸(棕榈油酸、棕榈酸、硬脂酸和肉豆蔻酸)对红火蚁的搬尸行为无显著影响；单组分的油酸和亚油酸均能促进红火蚁的搬尸行为，浓度越高，搬尸行为越显著。10 μg/μL的油酸和亚油酸混合液对工蚁的搬尸行为也具有显著的促进效果，低浓度的混合液对其无明显的促进作用(P>0.05)。【结论】结果提示油酸和亚油酸可调控红火蚁的搬尸行为，其他脂肪酸对红火蚁搬尸行为不产生影响。

Influence of fatty acids on the necrophoric behavior of the red imported fire ant,Solenopsis invicta (Hymenoptera: Formicidae)

【Aim】 After death, worker corpse is vulnerable to pathogen infection, which is harmful to the health of the entire nest of ants. To avoid horizontal transmission of pathogens, live workers recognize corpses by changes in chemical cues from corpses and removed them to refuse piles. This study aims to test the behavioral response of workers of the red imported fire ant, Solenopsis invicta to six fatty acids including oleic acid, linoleic acid, palmitokic acid, palmitic acid, stearic acid and myristic acid, which may play important roles in its necrophoric behavior. 【Methods】 The fatty acid components of body extracts of live and dead ant workers were analyzed with GC-MS. The necrophoric behavioral responses of S. invicta workers to six fatty acids (10 μg/μL), the single component oleic acid or linoleic acid at different concentrations (0.75 and 3 μg/μL) and their mixture at different concentrations (0.01, 0.1, 1 and 10 μg/μL) were tested with filter paper disc method. 【Results】 Only linoleic and oleic acids were detected from the corpses of S. invicta worker. The fire ant workers did not significantly respond to four fatty acids, i.e., palmitokic acid, palmitic acid, stearic acid and myristic acid. Both single linoleic acid and oleic acid could trigger significant necrophoric behavior of fire ant workers, which was dose-dependent. The mixture of linoleic acid and oleic acid at the 10 μg/μL concentration could also trigger significant necrophoric behavior of fire ant workers, while showed no significant effect at other lower concentrations.【Conclusion】 The results suggest that oleic acid and linoleic acid, but not other fatty acids, play important roles in triggering necrophoric behavior of S. invicta workers.