The effect of host quality and crowding on the settling and take‐off of cereal aphids

SUMMARY Settling and take‐off behaviour of Sitobion avenae was studied in the laboratory using infested and uninfested wheat at a range of developmental stages. Of the later developmental stages of wheat alate S. avenae preferred to settle on and gave birth to relatively more offspring on flowering and watery‐ripe plants. The time to take‐off of alatae which matured on wheat was influenced by both the developmental stage of their host plant and the degree of crowding they experienced. All alatae flew but those isolated on flowering plants stayed longer than those crowded or isolated on any of the other developmental stages tested. Similarly the number of offspring produced before take‐off was inversely related to the degree of crowding and positively to the time spent on a plant before take‐off.