Biological Control Attempts by Introductions Against Pest Insects in the Field in Canada

Abstract

This is an analysis of the attempts to colonize at least 208 species of parasites and predators on about 75 species of pest insects in the field in Canada. There was colonization by about 10% of the species that were introduced in totals of under 5,000 individuals, 40% of those introduced in totals of between 5,000 and 31,200, and 78% of those introduced in totals of over 31,200. Indications exist that initial colonizations may be favoured by large releases and by selection of release sites that are semi-isolated and not ecologically complex but that colonizations are hindered when the target species differs taxonomically from the species from which introduced agents originated and when the release site lacks factors needed for introduced agents to survive or when it is subject to potentially-avoidable physical disruptions. There was no evidence that the probability of colonization was increased when the numbers of individuals released were increased by laboratory propagation. About 10% of the attempts were successful from the economic viewpoint. Successes may be overestimated if the influence of causes of coincidental, actual, or supposed changes in pest abundance are overlooked. Most of the successes were by two or more kinds of agents of which at least one attacked species additional to the target pests. Unplanned consequences of colonization have not been sufficiently harmful to warrant precautions to the extent advocated by Turnbull and Chant but are sufficiently potentially dangerous to warrant the restriction of all colonization attempts to biological control experts. It is concluded that most failures were caused by inadequate procedures, rather than by any weaknesses inherent in the method, that those inadequacies can be avoided in the future, and therefore that biological control of pest insects has much unrealized potential for use in Canada.

Global patterns of introduction effort and establishment success in birds

“…The few previous studies that have included information on propagule size have found it to be the major correlate of success, but to date such studies have been either localized in extent (Newsome & Noble 1986;Veltman et al 1996;Duncan 1997) or limited in scope (Beirne 1975;Dawson 1984;Greustad 1999). Our results show that propagule pressure is the primary determinant of introduction success for an entire higher taxon, where releases have occurred for a variety of reasons (e.g.…”

Active Ingredients in Cade Oil That Synergize Attractiveness of α-Ionol to Male <I>Bactrocera latifrons</I> (Diptera: Tephritidae)

“…Classical biological control literature is divided over whether it is a better strategy to release a large number of parasitoids in a few places (e.g., Beirne 1975;Cameron et al 1993;Grevstad 1999) or a small number of insects in many places (e.g., Campbell 1976;Memmot et al 1998) to increase the probability of establishment. In the present study, over 10,000 D. kraussii adults were released over eight separate occasions, which is a large number in reference to the threshold of 1,000 insects recommended by Hopper and Roush (1993) as necessary to ensure establishment of introduced parasitoids.…”

No evidence for establishment of the wasp parasitoid,Sphecophaga vesparum burra(Cresson) (Hymenoptera: Ichneumonidae) at two sites in New Zealand

“…Biological control literature is divided over whether it is a better strategy to release a large number of individuals in a few places (e.g., Beirne 1975;Cameron et al 1993;Grevstad 1999), or a small number of individuals in many places (e.g., Campbell 1976;Memmott et al 1998) to increase the overall probability of establishment. The optimum establishment strategy is likely to vary with species and environment.…”