History and Impact of Gypsy Moth in North America and Comparison to Recent Outbreaks in Europe

Abstract

The article summarizes information about the introduction, spread, population dynamics, and impacts of the gypsy moth in North America and elucidates comparisons with the importance of this forest pest in Europe. Additionally, the natural enemies (parasites, predators, and pathogens) that help regulate gypsy moth populations, are discussed at length. Gypsy moth outbreaks on both continents are associated with the presence, abundance and characteristics of oak forests. While oak forests in Europe are rather fragmented and their area has declined, oak forests in North America are both extensive and contiguous. Consequently there is an obvious disparity in the magnitude, impact, and synchrony of gypsy moth outbreaks in Europe and in North America. Even if the frequency and severity of outbreaks in Europe will increase in the future, the spread of outbreaks will be limited by the availability of suitable hosts and climatic factors. Conversely, gypsy moth will continue to spread to West and South in the United States and the area infested will increase significantly until it eventually occupies the natural distribution of oak species. Because of this prognosis, an emphasis has been placed on slowing the spread of the gypsy moth rather than treating defoliating populations.