Environmental Impacts Of Classical Biological Control

The Safe Use of Fungi for Biological Control of Weeds

“…As McFadyen (1998) observed, despite improved techniques for risk analysis and a good track record, with some notable and even spectacular successes, opposition to the introduction of biocontrol agents appears to be increasing (Howarth, 1991;Simberloff & Stiling, 1996). Indeed, McFadyen (1998) made an éloquent plea, stressing that unnecessary-necessary and ever increasing bureaucracy and red tape should not be allowed to discourage or disrupt classical biological control initiatives which, for many alien weed problems, offer ".... the only safe, practical and economically feasible method that is sustainable in the long term".…”

Invasive Melastomataceae in Seychelles

“…Due to the large number of brief reports of control attempts for this species and the dispersion of the published accounts, detailed consideration of control measures is beyond the scope of the present paper. It is worth noting that any attempt at this means of control in Seychelles would probably encounter the usual problems of biological control (Howarth, 1991), with the additional complication of further endangering the reduced populations of Melastoma malabathricum, which used to be an important constituent of natural habitats on Silhouette. It has been suggested that careful tests for hostspecificity prior to release would eliminate this possibility.…”

“…It has been suggested that careful tests for hostspecificity prior to release would eliminate this possibility. However, the cumulated evidence of many years of biological control programmes suggests that it is no longer possible to believe that such solutions are reliable, given the possibilities of dietary switching and local phytochemical changes that may induce such switching (Howarth, 1991). Although cutting and uprooting the main areas affected would be labour intensive and would require continuous management this is probably the most reliable means of exercising some control of C. hirta without threatening already reduced populations of rare plants.…”

Effects of mass releases of Trichogramma brassicae on predatory insects in maize

“…Non-target effects have become important in insect biological control projects over the past decade, and several review papers have addressed this issue (Howarth, 1991;Simberloff & Stiling, 1996;Stiling & Simberloff, 2000;Lynch et al, 2001). Non-target effects may arise if either non-target herbivores or natural enemies present in the habitat are attacked by the biological control agent.…”

“…Natural enemies may be affected in two ways: they may be directly attacked by the biological control agent or may suffer from interspecific competition by the biological control agent. There is a general agreement that the potential for non-target effects to occur is higher in polyphagous than in specialist parasitoids (Howarth, 1991). Egg parasitoids of the genus Trichogramma are known to parasitise mainly species within the order Lepidoptera, but were also reared from hosts of other insect orders.…”