Habitat diversification for improving biological control: abundance of Anagrus epos (Hymenoptera: Mymaridae) in grape vineyards
1996
Murphy, B.C. | Rosenheim, J.A. | Granett, J.
A frequently cited habitat diversification tactic is the use of prune tree refuges that support overwintering populations of Anagrus epos (Girault), a mymarid egg parasite of the western grape leafhopper, Erythroneura elegantula Osborn, in vineyards. Here we test the effect of prune trees on early-season abundance of adult A. epos in vineyards. A. epos was found in vineyards downwind of prune trees at more than twice the densities of vineyards lacking prune trees, despite significant variation in A. epos immigration from sources outside the prune tree-vineyard system. Densities of A. epos overwintering within prune trees explained a significant amount of the variation in A. epos trap capture in vineyards. Furthermore, another factor associated with prune trees was found to influence A. epos abundance in vineyards: a windbreak effect created by the prune trees concentrated dispersing A. epos on the leeward side of the prune trees, thereby further enhancing A. epos numbers.
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