A new management tactic for Eucryptorrhynchus scrobiculatus (Coleoptera: Curculionidae) based on factors influencing the weevil population density.

BACKGROUND: The tree of heaven root weevil, Eucryptorrhynchus scrobiculatus (TRW), is one of the most damaging pests of Ailanthus altissima in China. A limited number of studies have examined the effects of different variables on the population density of TRW adults. We investigated the relative impacts of the diameter at breast height of host trees (DBH), number of tree species in plots (NTS), weed coverage rate of the host tree base (WCR), plot area (PA), distance from plots to the nearest farmland (DNF), nearest human community (DNHC), nearest irrigation canal (DNIC), and nearest road (DNR) on TRW population density. We then evaluated the effect of removing weeds at the base of the tree trunk (RW) on TRW population density.

RESULTS: We found that DBH, WCR, PA, and DNHC significantly affected the population density of TRW adults, whereas NTS, DNF, DNIC, and DNR did not. Adult TRW density was positively correlated with DBH, WCR, and PA but was negatively correlated with DNHC. Further field trials showed that RW treatments significantly reduced the density of adult TRW (an average annual reduction of 51.7% compared to untreated trees).

CONCLUSION: This information on the factors affecting the population density of TRW promoted the development of new TRW management strategies. Our results demonstrate that RW is an effective method for reducing the population density of TRW adults. Therefore, this new physical method using RW could be recommended as an alternative for TRW management in the framework of integrated pest management. © 2021 Society of Chemical Industry.