First record of antipredator behavior in the gall‐forming aphid Mordwilkoja vagabunda

Abstract The gall‐forming aphid Mordwilkoja vagabunda has been an out‐group in molecular studies of the evolution of social behavior in the Pemphigus genus, but Mordwilkoja aphids have not previously been assayed for social behavior, such as altruistic defense. This study reports experiments carried out in July in Ithaca, NY, in which nymphs (immature aphids) of M. vagabunda were video‐recorded under a stereomicroscope while they encountered pyralid moth larvae in a plastic arena. Mordwilkoja vagabunda nymphs of all instars used their legs to claw moth larvae while pressing their rostrums against the larvae, possibly to pierce the cuticle. Many of the attacking aphids were alatoid nymphs, rather than the specialized first‐instar soldiers typically observed in Pemphigus species. Mordwilkoja vagabunda nymphs moved in bursts that sometimes became synchronized among several aphids in the same vicinity. These synchronized, rhythmic movements may be antipredator defense strategies comparable to the collective twitching and kicking response observed in colonies of Aphis nerii and other aphid species. Defensive behaviors by M. vagabunda nymphs may be altruistic fortress defense strategies, which maximize the inclusive fitness of the clone.