Some effects of crowding on the biology of Megoura viciae

SUMMARYCrowdingMegour a viciae(Buckton) on bean plants affects both the nymphs and adults. Crowded nymphs show a low mortality, develop more rapidly to produce light adults after a series of synchronized moults: isolated nymphs show a high initial mortality, develop more slowly to heavier adults, the duration of nymphal stages being extremely variable, with no synchronization of moulting. Development is discussed in terms of both weight gain and linear growth rate.Crowding does not affect adult mortality but it does reduce the rate at which nymphs are produced. The significance of these findings in relation to the formation and maintenance of the aphid colony is considered, and possible controlling factors are discussed.