RESUMEN
Lindgren funnel traps baited with aggregation pheromones are widely used to monitor and manage populations of economically important bark beetles (Coleoptera: Scolytidae). This study was designed to advance our understanding of how funnel trap catches assess bark beetle communities and relative abundance of individual species. In the second year (2005) of a 3-yr study of the bark beetle community structure in north-central Arizona pine (Pinus spp.) forests, we collected data on stand structure, site conditions, and local bark beetle-induced tree mortality at each trap site. We also collected samples of bark from infested (brood) trees near trap sites to identify and determine the population density of bark beetles that were attacking ponderosa pine, Pinus ponderosa Douglas ex Lawson, in the area surrounding the traps. Multiple regression models indicated that the number of Dendroctonus and Ips beetles captured in 2005 was inversely related to elevation of the trap site, and positively associated with the amount of ponderosa pine in the stand surrounding the site. Traps located closer to brood trees also captured more beetles. The relationship between trap catches and host tree mortality was weak and inconsistent in forest stands surrounding the funnel traps, suggesting that trap catches do not provide a good estimate of local beetle-induced tree mortality. However, pheromone-baited funnel trap data and data from gallery identification in bark samples produced statistically similar relative abundance profiles for the five species of bark beetles that we examined, indicating that funnel trap data provided a good assessment of species presence and relative abundance.
Asunto(s)
Escarabajos , Pinus ponderosa/parasitología , Corteza de la Planta/parasitología , Animales , Arizona , Ecosistema , Densidad de Población , Proyectos de InvestigaciónRESUMEN
Insecticides that might protect pine trees from attack by engraver beetles (Ips spp.) have not been rigorously tested in the southwestern United States. We conducted two field experiments to evaluate the efficacy of several currently and potentially labeled preventative insecticides for protecting high-value ponderosa pine, Pinus ponderosa Dougl ex. Laws., from attack by engraver beetles. Preventative sprays (0.19% permethrin [Permethrin Plus C]; 0.03, 0.06, and 0.12% bifenthrin [Onyx]; and 1.0 and 2.0% carbaryl [Sevin SL] formulations) and systemic implants (0.875 g per capsule acephate [Acecap] and 0.650 g per capsule dinotefuran) were assessed on bolts (sections of logs) as a surrogate for live trees for a period of 13 mo posttreatment. The pine engraver, Ips pini (Say), was the most common bark beetle found attacking control and treated bolts, but sixspined ips, Ips calligraphus (Germar), and Ips lecontei Swain also were present. After approximately 13 mo posttreatment in one experiment, the spray treatments with 2.0% carbaryl, 0.19% permethrin, and 0.06 or 0.12% bifenthrin prevented Ips attack on the bolts at a protection level of > or = 70%. The acephate and dinotefuran systemic insecticides, and the 0.03% bifenthrin spray, provided inadequate (< or = 36%) protection in this experiment. For the other experiment, sprayed applications of 1.0% carbaryl, 0.19% permethrin, and 0.06% bifenthrin prevented beetle attack at protection levels of > or = 90, > or = 80, and > or = 70%, respectively, when bolts were exposed to Ips beetle attack for approximately 9-15 wk posttreatment. The sprays with 0.19% permethrin and 0.06% bifenthrin also provided > or = 90% protection when bolts were exposed for approximately 15-54 wk posttreatment. We concluded that under the conditions tested, 1.0 and 2.0% carbaryl, 0.19% permethrin, and 0.06 and 0.12% binfenthrin were acceptable preventative treatments for protecting ponderosa pine from successful engraver beetle attack for one entire flight season in the U.S. Southwest.
Asunto(s)
Escarabajos/efectos de los fármacos , Insecticidas/farmacología , Pinus ponderosa/parasitología , Animales , Factores de TiempoRESUMEN
The coupling of the valley drift (VALDRIFT) atmospheric dispersion/deposition model with the agricultural dispersal (AGDISP) aircraft wake model generates a modeling system for predicting the off-target drift of pesticides sprayed in a mountain valley. The approach uses the AGDISP near-field spray model to estimate the mass fraction of pesticide remaining airborne after initial application, then the VALDRIFT complex terrain model to estimate the drift of pesticide from the target area. The modeling system inputs include detailed spray information, a measure (or estimate) of winds in the valley, and the valley topographic characteristics; the results are pesticide concentrations throughout the valley atmosphere and pesticide deposition to the valley surface. The AGDISP and VALDRIFT models are operated independently, with the results from AGDISP being used as input to VALDRIFT through user-created data files. The modeling system was evaluated using pesticide drift data from spray trials conducted in the Mill Creek Canyon of Utah's Wasatch Mountains, USA, during the late spring of 1993. The predicted deposition compared within a factor of three of the observations (70% of the time) at all sampling locations extending several kilometers down-valley from the spray treatment block. The overall average ratio of predicted-to-observed deposition was 0.9.