Collective Defense of Aphis nerii and Uroleucon hypochoeridis (Homoptera, Aphididae) against Natural Enemies
A. nerii colonies feeding on Oleander (A–C) and U. hypochoeridis colonies feeding on Hypochoeris radicata (D–F). CTKR of A. nerii colonies is restricted to those colonies consisting of bucking individuals (a lift abdomen) and some space left for twitching (B). The colony in A is not responding to a rapidly approaching object like a ball pen (diameter = 12 mm, tip size = 1 mm). C Aphidius colemani after less successful oviposition attempts. E Members of an U. hypochoeridis colony in defense posture. F An oviposition attempt of Aphidius colemani before this parasitoid was repelled from an U. hypochoeridis colony through consecutive CTKRs.