Due to their high growth rate, aphid colonies are especially attractive to predators and parasitoids, which promoted the evolution of various defence mechanisms. In non-myrmecophilous aphid species colonies defence is accomplished by virtue of physical and chemical defence with the potential to deter or even repel aphid enemies. In some aphid species, such as Aphis nerii and Uroleucon hypochoeridis, collective defence in the form of synchronous abdomen twitching and leg kicking can be observed in various defence contexts. Preliminary observations suggest collective physical defence (CPD) to cause a repelling effect against insects approaching from the air. A high predation pressure exerted by these natural enemies suggests that CPD may have evolved in parallel multiple times in aphid species lacking a common ancestor.
Colonies will be exposed to vibrational, optical and acoustical stimuli in playback experiments to search for thresholds in triggering the defence reaction. Finally, the evolution of CPD will be reconstructed in a phylogenetic approach encompassing different species belonging to the subfamily of Aphidinae. The presence of alarm pheromones and their mode of action possibly involved will be studied in an analytical approach as well as in a behaviour assay.

FWF project P 25709: Collective defense in non-myrmecophilous aphid species and their evolution.