Laricobius nigrinus Fender (Coleoptera: Derodontidae), native to western North America is being evaluated as a potential biological control agent of the hemlock woolly adelgid, Adelges tsugae Annand (Homoptera: Adelgidae) in the eastern United States. Members of the genus Laricobius are known to feed on adelgids. The hemlock woolly adelgid is an exotic insect pest of eastern (Tsuga canadensis (L.) Carrière) and Carolina (T. caroliniana Engelmann) hemlocks.
Temperature-dependent development was determined for egg, larval, pre-pupal and pupal stages of L. nigrinus at five constant temperatures (9, 12, 15, 18 and 21°C). Linear regressions of developmental rate against temperature were used to determine the minimum threshold temperature for each developmental stage. To validate the model, field data were collected during a 2-year field study near Victoria, British Columbia. Twig cuttings of T. heterophylla (Raf.) Sargent infested with A. tsugae were made. All eggs and larvae of L. nigrinus per cm of twig were counted throughout the development period. These numbers were transformed to proportions for each date. The model was run using daily maximum and minimum air temperatures.
Comparison of thermal development requirements with A. tsugae in Virginia will help determine whether L. nigrinus is synchronized with suitable prey stages of the hemlock woolly adelgid. This will provide clues to its suitability as an effective biological control agent of A. tsugae in the eastern United States.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA