Effects of aerial insecticide sprays on ant communities to control pine wilt disease in Korean pine forests

Pine wilt disease is one of the most serious diseases in the pine forests of Korea. Since the first report of the disease in Busan, Korea, in 1988, the disease has been gradually spreading into neighboring regions and now occurs in many regions of the southern part of the Korean Peninsula. The control of the disease is focused on the killing of the sawyer, Monochamus alternatus, an insect vector, by aerial insecticide spraying for adult control and by fumigation or burning infected trees for larval control. This study was conducted to evaluate the effects of aerial insecticide application on pine forest fauna by comparing ant communities in insecticide-sprayed and unsprayed areas. Samples were collected from five regions using three different sampling methods (pitfall trap, sweeping net, and shaking net). The results showed that community indices such as abundance, species richness and species diversity were not significantly different between insecticide-sprayed sites and unsprayed sites. According to a cluster analysis and a correspondence analysis, ant communities were generally grouped based on the location of the sampling sites with a slight variation of insecticide application, but not grouped by insecticide application, showing that ant community structures were not significantly different between the insecticide-sprayed sites and the unsprayed sites. Our results, overall, support the theory that the impact of the aerial insecticide application on pine forest fauna may be less severe than expected.