Killing Adult Elm Bark Beetles in the Bark, 1981

Abstract In 1979 five elm bolts, each 8 inches long by 4 inches diam and in separate 5-gal screened lard cans, were each infested with 25 male and 25 female adults. The cans were in a continuously lighted room maintained at 85°F. After 3 wk these parent adults were removed from the logs and cans with a vacuum cleaner, thus leaving the logs infested only with progeny as eggs and larvae under the bark. One log was set aside as an untreated check and each of the other logs was sprayed to run-off with a particular insecticide using a laboratory paint gun sprayer. The insecticides were used at the equivalent rate of 16 lb AI/100 gal spray except Pydrin was used at 3.2 lb AI/100, which is 16X the recommended agricultural rate. Sprays were buffered to pH 6.0. After drying the sprayed, infested logs were again confined in the lard cans at ca 75°F. From 3 to 11 wk after treatment progeny adults emerged from the logs and were counted. After adult emergence ceased the bark on each log was examined under a 10-power microscope and the bark routed to the depth of the bark beetle pupal chamber with a drill bit in a Moto-Tool. The dead adults in the bark were counted. Their locations varied from the pupal chamber to partial protrusion from the bark, with the more toxic insecticides stopping movement nearer the pupal chambers. This experiment was repeated again in 1980 and in 1981. With each year serving as a replicate the 3 years data were subjected to a 2-way ANOVA.