A phloem sandwich allowing attack and colonization by bark beetles (Coleoptera: Scolytidae) and associates
Much of the life cycles of bark beetles and their associates are spent under the bark of the host tree and are impossible to observe under completely natural conditions. To observe the behavior and development of insects in the phloem layer, phloem sandwiches have been developed, in which a piece of bark and phloem is removed from a live tree and pressed against a glass plate (Bedard, 1933, J. Econ. Entomol. 26: 1128-1134; Borden, 1969, Can. Entomol. 101: 870- 878; Schrnitz, 1972, Can. Entomol. 104: 1723-1728; Salom et al., 1986, J. Entomol. Sci. 21: 43-51; Langor and Raske, 1987, Can. Entomol. 119: 965-992). Previous designs (e.g., Kinn and Miller, 1981, USDA-FS Res. Note 50-239) required that the insects be placed into the sandwich by the researchers. This has precluded studies of the attack process (e.g., response to aggregation pheromones) and of the interactions among naturally-created combinations and densities of species. We report on a modification which allows insects to freely and naturally colonize the phloem sandwich.