Approaches to Forecasting Damage by Invasive Forest Insects and Pathogens: A Cross-Assessment

Abstract

Nonnative insects and pathogens pose major threats to forest ecosystems worldwide, greatly diminishing the ecosystem services trees provide. Given the high global diversity of arthropod and microbial species, their often unknown biological features or even identities, and their ease of accidental transport, there is an urgent need to better forecast the most likely species to cause damage. Several risk assessment approaches have been proposed or implemented to guide preventative measures. However, the underlying assumptions of each approach have rarely been explicitly identified or critically evaluated. We propose that evaluating the implicit assumptions, optimal usages, and advantages and limitations of each approach could help improve their combined utility. We consider four general categories: using prior pest status in native and previously invaded regions; evaluating statistical patterns of traits and gene sequences associated with a high impact; sentinel and other plantings to expose trees to insects and pathogens in native, nonnative, or experimental settings; and laboratory assays using detached plant parts or seedlings under controlled conditions. We evaluate how and under what conditions the assumptions of each approach are best met and propose methods for integrating multiple approaches to improve our forecasting ability and prevent losses from invasive pests.

Identifying the generalizable controls on insect associations of native and non‐native trees

“…Identifying and predicting the actual insect–host associations before the associations can occur in the native range of the host can be an important tool to guide risk analyses to inform prevention and surveillance activities. Such predictions could be accomplished in the future through a combination of modeling efforts, like that described here, as well as by experimental sentinel plantings (Eschen et al., 2019 ; Raffa et al., 2023 ).…”

Hosts and impacts of elongate hemlock scale (Hemiptera: Diaspididae): A critical review

“…Widespread tree mortality from Fiorinia externa has never been documented, even on preferred hosts. Evidence from prior pest activity and sentinel trees ( 62 ) indicates that although future host mortality from F. externa is possible, extensive host mortality is unlikely.…”

Forest Health in the Southern Cone of America: State of the Art and Perspectives on Regional Efforts

“…Research is needed to address critical gaps in our abilities to forecast and manage the impacts of forest pests in natural, commercial, and urban forest ecosystems [70]. For example, the development of new and effective management techniques for important pests, such as native leaf-cutting ants, is an urgent challenge due to increasing restrictions on the use of chemical-based insecticides [71][72][73].…”