Factors affecting settlement rate of the hemlock woolly adelgid, Adelges tsugae, on eastern hemlock, Tsuga canadensis
1 We assessed the importance of several factors potentially affecting the settlement rate of the invasive hemlock woolly adelgid Adelges tsugae (Hemiptera: Adelgidae) on uninfested foliage of the eastern hemlock, Tsuga canadensis. We conducted our experiments in Massachusetts (U.S.A.) with overwintering sistens adelgids, and applied standard densities of infested foliage to uninfested branches in a planned multiple-comparison design.
2 Settlement rates of progrediens crawlers produced by the overwintering sistens were highest when adelgid-infested foliage was loosely attached to uninfested foliage and both branches were then enclosed in a mesh sleeve.
3 Early-emerging crawlers settled at a higher rate than did late-emerging crawlers.
4 Increasing the density of infested branches did not affect settlement rates.
5 We also tested whether less severe winter conditions improved settlement, and found that overwintering infested foliage in a refrigerator decreased settlement rate relative to foliage overwintered outdoors.
6 Our results suggest a protocol for adelgid inoculations that could substantially increase the success rate of experimental manipulations and encourage additional research on the population dynamics of this pest.
Document Type: Research Article
Affiliations: Department of Plant, Soil, and Insect Sciences, University of Massachusetts at Amherst, Amherst, MA 01003, U.S.A.
Publication date: August 1, 2007