Insect parasitoids : a Canadian perspective on their use for biological control of forest insect pests

Abstract

An overview of biological control programs against forest insect pests is presented with emphasis on Canadian case histories. The work is examined in the context of conservation, introduction, and augmentation (environmental manipulation and inoculative and inundative release) of insect natural enemies, specifically parasitoids. Historically, studies have concentrated on introductions of exotic parasitoids for control of introduced pests where a number of successes have been recorded. More recent work has entailed inoculative and inundative releases of parasitoids against native pests in an attempt to establish new host-parasitoid relationships to reduce pest populations. These have had limited success and are still being explored by Canadian researchers. Current strategies for using natural enemies are inundative release of native species against native pests and conservation of native parasitoids through selective insecticide timing and forest manipulation. Future directions in biological control programs will include these approaches with increased emphasis on biotechnology and the genetic selection or manipulation of 'desired strains' for release. Continued ecological studies will be essential to ensure a more complete understanding of the interaction between these 'selected parasitoids' and the forest/tree parameters which will influence their success (tri-trophic interactions). These parameters, such as tree vigour (pest resistance), spatial distribution and diversity, will also be targeted for selection to improve the effect of insect natural enemies in the forest environment.

A history of biological control in Canadian forests, 1882–2014

“…Historically, Canada has been a world leader in the field of biological control for forest insects (Pschorn-Walcher 1977;Kelleher and Hulme 1984;Smith 1993), and many of its biological control programmes have been considered successful (e.g., Munroe 1971;Hulme 1988;Wallace 1995). Much of this success is rooted in the extensive population studies and basic research typical of Canadian forest entomology (Nealis and Wallace 1991;Quiring et al 2015).…”

Parasitoid Biodiversity and Insect Pest Management

“…Niche specialization, keystone species, potential cascade effects with parasitoid extinction, and the importance of parasitoids are all factors affecting this delicate balance (Greathead 1986, Hawkins et al 1992, LaSalle and Gauld 1993, Hawkins 1994. By the addition of one or more natural enemies from the country of origin, or the effect of host shifts by native predators or parasitoids, introduced pests may be brought under control (Huffaker 1969, Clausen 1978, Caltagirone 1981, Smith 1993, Van Dreische and Bellows 1996. Biological control programs in agricultural systems over the last century provide key insights into future problems that will be caused by habitat fragmentation, climate change, and loss of primary habitat in all ecosystems.…”