Studies of Predators of the Balsam Woolly Aphid Adelges piceae (Ratz.) (Homoptera: Adelgidae): IX. Pullus impexus (Muls.) (Coleoptera: Coccinellidae), An Introduced Predator in Eastern Canada,

Abstract

Pullus impexus (Muls.) is one of many species of predators that have been introduced into Eastern Canada since 1933 as part of a biological control program against the balsam woolly aphid, Adelges piceae (Ratz.) Delucchi (1954) has published many details of the systematics, biology, and natural control of this species in Europe where he found it to be associated with all A. piceae infestations. According to Pschorn-Walcher and Zwölfer (1960), it is one of a group of predators that are usually associated with lower population densities of A. piceae and other related adelgids, rhan are Aphidoletes thompsoni Möhn and Laricobius erichsonii Rosen. Because it is common on adelgid infestations in Europe and because it can easily be reared en masse, large numbers have been released in North America. The purpose of the present paper is to bring together available information on releases, life-history and natural control, and control value of this species, obtained from studies carried out over the past nine years in New Brunswick.