Natural enemies and environmental factors affecting the population dynamics of the gypsy moth

Abstract The population densities of the gypsy moth ( L ymantria dispar ; Lepidoptera: Lymantriidae) may reach outbreak levels that pose considerable economic and environmental impacts to forests in E urope, A sia, A frica and N orth America. Compared with the situation in its native European range feeding damage by gypsy moth is often found to be more severe in N orth America and other parts of the world. Thus, the release from natural enemies can be interpreted as an important cause for high feeding damages. Natural enemies, especially parasitoids, can cause delayed density‐dependent mortality, which may be responsible for population cycles. In N orth America where only few parasitoids have been introduced and the parasitism rates are considerably lower than in Europe, generalist predators play a larger role than in E urope. Many other factors seem to influence the population dynamics of the gypsy moth such as the host plants and weather. Nevertheless, much of the variability in population densities of the gypsy moth may be attributed to interacting effects of weather conditions and attack by natural enemies. In spite of the considerable number of studies on the ecology and population dynamics of the gypsy moth and the impact of their natural enemies, more quantitative information is required to predict the population dynamics of this pest species and to control its economic and ecologic impact.