Ips Bark Beetles Biological Control
From: Bellows, Thomas S. ,Carol Meisenbacher, and Richard C. Reardon, 1998, Biological Control of Arthropod Forest Pests of the Western United States: A Review and Recommendations, USDA, FS, FHTET-96-21.
The genus Ips contains 25 species recognized in the western United States, and these form the second most destructive group among the western bark beetles. The species are multivoltine (from two to five generations per year, occasionally univoltine at high latitudes). They typically attack windfalls, cut trees, slash, or trees weakened or predisposed to attack of drought or attack of other bark beetles. While Ips spp. have a number of predaceous and parasitic natural enemies, densities of Ips species appear to be largely limited by the quantity of available host material. In a quantity of freshly cut slash or windfall, a large beetle population can develop. This population usually does not remain at high densities once the breeding material is exhausted. Direct control of these beetles has rarely been practiced, because of the brevity and focused nature of these outbreaks. Management practices focus on limiting breeding material during logging operations, and on harvesting or salvaging windthrown timber. Direct control by felling infested trees and treating felled timber can be employed on extensively used areas, such as recreation areas.
The 25 species of Ips in North America are all native and have similar ecological contexts regarding the possibilities for biological control. We will examine Ips pini, the principal western species, as typical of this group.
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