Pruning can recover the health of wild apple forests attacked by the wood borer Agrilus mali in central Eurasia

Abstract

The invasive apple wood borer Agrilus mali Matsumura (Coleoptera: Buprestidae) threatens the viability of wild apple forests in Xinjiang, China, imperiling the preservation of apple germplasm resources in Central Eurasia. Pruning infested branches can reduce the likelihood of outbreaks of various pests and associated damage, but its efficacy and feasibility for managing A. mali has not been well-studied. Therefore, we examined the efficacy of pruning at three different times of the year in commercial orchards in 2018 and 2019. We evaluated the efficacy of pruning for longer-term sustainable management of A. mali in wild apple forests over a five-year period from 2016–2019. Autumn pruning resulted in mortality of all immature A. mali in pruned branches, increased flowering in individual trees, and a significant reduction in both pest density and tree damage on the landscape. Simulation modeling showed that a single well-timed pruning treatment could maintain low pest density for at least 6–10 years. Recurring pruning schedules may be an effective long-term management tool, suppressing A. mali populations in wild apple forests and facilitating ecosystem recovery. This practical tactic could prove instrumental in managing A. mali and sustaining ecosystem health, particularly in the face of future invasions in wild apple forests in central Eurasia.