Population ecology of winter moth (Operophtera brumata) on apple in relation to larval dispersal and time of bud burst.
The populations of Operophtera brumata (L.) on 8 cider apple trees of 4 cultivars were monitored from October 1972 until May 1975 in Western England. At three stages in the life-cycle there were significant differences in the densities of insects on different cultivars. There was significant variation between cultivars in the mortality occurring after oviposition and before larvae fed in the foliage. Larval density on each tree showed no relationship to egg density because of the importance of dispersal of newly-hatched larvae. Throughout the larval stages, more advanced buds were preferred to less advanced ones. The density of larvae in the foliage of each tree was related to the degree of development of the buds and foliage clusters, and this was shown to account for almost all of the intercultivar variation in larval density. Control of damage by O. brumata to fruit trees by the alteration of tree phenology is discussed.