Natural Population Densities of the European Red Mite 1 on Apple in Quebec

Abstract

During the period 1960–1967, the seasonal populations of Panonychus ulmi (Koch) were comparable from year to year. Peak densities occurred either in July or August. Summer mite densities were not necessarily related to initial densities of overwintering eggs. Natural-control factors resulted in an average survival of 45% from the overwintering eggs and 30% from the summer stages. Biotic factors responsible for the natural reduction were predacious mites, arachnids, coccinellids, pentatomids, thrips, and mirids. Abiotic factors were mainly ice, snow, and low temperatures.