EVOLUTION OF HOST-RANGE IN APHIDS

A simple model reveals one possible explanation of why aphids and orga nisms with a similar bionomy, i.e., have a high rate of population inc rease, a short adult life, and are time - limited dispersers, are so h ighly host specific. It indicates that small differences in host suita bility amplified by the high rate of population increase over a number of generations could compensate for the losses incurred in searching for the best host plant.