The evolutionary biology of sterile soldiers in aphids

The discovery of a sterile soldier caste in aphids by Shigeyuki Aoki offered behavioural ecologists new and interesting subjects for the study of insect sociality. Quantitative studies on the behaviour of soldiers and the population and genetic consequences are, however, scant. This review summarizes the distribution and peculiarities of sterile soldiers in different aphid taxa and also reports on phenomena that may relate to the evolution of aphid soldiers.