ABSTRACT
The efficacy of tree injected with emamectin benzoate (EB) against the Asian long-horned beetle (ALB) was tested in a heavily infested willow forest in Beijing, China. In a 1.7-ha plot, 240 out of 310 trees were treated with two EB formulations at various rates. After fall application, the larval population decreased by 89% in the following spring and by >99% during the second year detected by monitoring new frass emission from marked holes. Consequently, the number of exit holes of emerging adults decreased to 0 in the second year. Re-infestation occurred in the third year after application. This high efficacy and lasting activity might be contributed to: a) a favorable translocation of EB in trees when injected into the sapwood; b) the high intrinsic activity against ALB larvae with LC50 of 20-30 ppb; and c) a reduced lifespan of ALB adults by over 60% when feeding on twigs of EB-treated trees. On untreated control trees, the larval population decreased during the first winter. In the second year after application, the larval population was wiped out during winter and a re-infestation started from border trees by adults flying in from outside the trial plot. This pattern indicates an eradication of the ALB population in the 1.7-ha plot can be expected 2 yr after EB treatment. The benefit of treating with EB on the surrounding population was observed in both the untreated trees and imidacloprid-treated trees, suggesting that treatment of EB benefits both the treated trees and the surrounding trees in the area.
Subject(s)
Coleoptera , Insecticides , Animals , China , Ivermectin/analogs & derivativesABSTRACT
Near-surface atmospheric CO2 concentration and δ13C value in four greenspaces and on their adjacent roads in Beijing were measured by off-axis integrated cavity output spectroscopy to analyze the influence of urban greenspace on spatial distribution of near-surface atmospheric CO2. The results showed that atmospheric CO2 concentration and δ13C value varied substantially both temporally and spatially. The highest CO2 concentration was found in the urban area, followed by the suburbs, and the lowest CO2 concentration was in the outer suburbs. There was a clear near-surface atmospheric CO2 dome, but a reverse pattern for δ13C value. During the non-growing season, the ΔCO2 and Δ13C between greenspace and adjacent roads were low. The differences among the four experimental sites were not significant. In the growing season, the ΔCO2 and Δ13C at the BLA4th RR (Beijing Institute of Landscape Architecture and 4th Ring Road) and BOP5th RR (Beijing Olympic Forest Park and 5th Ring Road) in urban areas were significantly higher than those at DPSR (Daoxianghu Park and Sujiatuo Road) and MTGMR (Mentougou forest experimental station and an adjacent road) in the suburbs. During the growing and non-growing seasons, CO2 concentration of all examined sites was significantly positively related with the traffic volume, indicating that traffic volume was an important factor affecting the spatial distribution of CO2. The δ13C value was significantly negatively related with traffic volume during non-growing season, but no significant relationship was found during the growing season. The ΔCO2 concentration between the four green-spaces and their adjacent roads were significantly negatively related with leaf area index (LAI). The Δ13C value were significantly logarithmically related to LAI. Results from stepwise regression showed that solar radiation, temperature, and LAI significantly affected ΔCO2 in urban areas and suburbs during the growing season, and that temperature and solar radiation were the major driving factors for Δ13C. During the growing season, plants in the greenspaces assimilated CO2 via photosynthesis and thus reduced the near-surface atmospheric CO2 concentration. Our results indicate that green-spaces play a positive role in improving ecological environment in urban areas.
