1. Establishment and postrelease recovery of Laricobius nigrinusand Laricobius osakensis(Coleoptera: Derodontidae), released for biological control of Adelges tsugae(Hemiptera: Adelgidae), in the Northeastern United States
- Author
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Crandall, Ryan S, Chandler, Jennifer L, Dietschler, Nicholas J, Andersen, Jeremy C, and Elkinton, Joseph S
- Abstract
Hemlock woolly adelgid (HWA), Adelges tsugaeAnnand, is a major forest pest in the eastern United States responsible for killing millions of eastern hemlock, Tsuga canadensis(L.) Carrière and Carolina hemlock, T. carolinianaEngelmann. The US biological control program for HWA has largely invested in the rearing and release of Laricobius nigrinusFender and more recently L. osakensisMontgomery and Shiyake. Though the establishment of L. nigrinushas been well-documented in the southern, mid-Atlantic, and coastal portions of the northeastern United States, documentation in interior areas of the northeastern United States is limited. Establishment of L. osakensisin the northeastern United States has not yet been documented. Release locations in the northeastern United States were surveyed for L. nigrinusand L. osakensisestablishment to examine the relationship between establishment success and winter temperatures, as winter minimum temperatures likely limit the northern range of introduced Laricobiusspecies. Our results suggest that L. nigrinusestablishment is limited by winter minimum temperatures and that the probability of establishment declines as absolute minimum temperature declines. We found L. nigrinusestablished at sites in Maine, New York, and Pennsylvania, but did not recover any L. nigrinusin Massachusetts, New Hampshire, or Vermont. Similarly, we found L. osakensisestablished at sites in New York and Pennsylvania and recovered individuals in Maine, though further sampling is necessary to confirm presence of the F3generation. We also report the first field observation of reproduction of silver flies, Leucotaraxis argenticollis(Diptera: Chamaemyiidae), released predator of HWA, in the eastern United States.
- Published
- 2023
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