Instituto Valenciano de Investigaciones Agrarias, Plant Protection and Biotechnology Research Center, Moncada, Spain.
Wageningen University, Laboratory of Entomology, Wageningen, The Netherlands.
Proc Biol Sci. 2021 Jan 13;288(1942):20201684. doi: 10.1098/rspb.2020.1684. Epub 2021 Jan 6.
One of the most studied and best-known mutualistic relationships between insects is that between ants and phloem-feeding insects. Ants feed on honeydew excreted by phloem-feeding insects and, in exchange, attack the phloem feeders' natural enemies, including parasitic wasps. However, parasitic wasps are under selection to exploit information on hazards and avoid them. Here, we tested whether parasitic wasps detect the previous presence of ants attending colonies of phloem feeders. Behavioural assays demonstrate that wasps left colonies previously attended by ants more frequently than control colonies. This behaviour has a potential cost for the parasitic wasp as females inserted their ovipositor in fewer hosts per colony. In a further bioassay, wasps spent less time on papers impregnated with extracts of the ant cues than on control papers. Gas chromatography coupled with mass spectrometry analyses demonstrated that ants left a blend of cuticular hydrocarbons when they attended colonies of phloem feeders. These cuticular hydrocarbons are deposited passively when ants search for food. Overall, these results suggest, for the first time, that parasitic wasps of honeydew producers detect the previous presence of mutualistic ants through contact infochemicals. We anticipate such interactions to be widespread and to have implications in numerous ecosystems, as phloem feeders are usually tended by ants.
昆虫之间最受研究和最知名的共生关系之一是蚂蚁和韧皮部取食昆虫之间的关系。蚂蚁以韧皮部取食昆虫排泄的蜜露为食，作为回报，它们会攻击韧皮部取食者的天敌，包括寄生蜂。然而，寄生蜂受到选择的压力，以利用有关危险的信息并避免这些危险。在这里，我们测试了寄生蜂是否能够检测到先前有蚂蚁在取食韧皮部的昆虫群体中出现。行为测定表明，与对照群体相比，寄生蜂更频繁地离开先前有蚂蚁光顾过的群体。这种行为对寄生蜂来说具有潜在的成本，因为雌性寄生蜂在每个群体中插入的产卵器数量减少。在进一步的生物测定中，寄生蜂在与蚂蚁信息素提取物浸渍的纸张上花费的时间少于对照纸张。气相色谱-质谱联用分析表明，当蚂蚁在取食韧皮部的昆虫群体中觅食时，它们会留下混合的表皮碳氢化合物。当蚂蚁寻找食物时，这些表皮碳氢化合物会被动沉积。总的来说，这些结果首次表明，蜜露生产者的寄生蜂通过接触信息素来检测先前存在的共生蚂蚁。我们预计这种相互作用会很普遍，并对众多生态系统产生影响，因为通常有蚂蚁照顾韧皮部取食者。
