# Predicting Phloeosinus cupressi (Coleoptera: Curculionidae: Phloeosinus) Distribution for Management Planning Under Climate Change

## TL;DR

This study predicts the future spread of an invasive bark beetle, Phloeosinus cupressi, under climate change to help manage its impact on Cupressus trees globally.

## Contribution

The study introduces a predictive model using CLIMEX and random forest to forecast the beetle's distribution under future climate scenarios.

## Key findings

- Suitable habitats for P. cupressi are projected to expand northward under future climate conditions.
- Climatic variables like coldest-quarter precipitation and annual temperature range are key drivers of distribution.
- Regions like southern Europe and South China may see reduced suitability, while areas in Argentina and Australia may become more suitable.

## Abstract

Phloeosinus cupressi Hopkins poses a serious threat to forest ecosystems and urban greenery worldwide. While currently absent from China, future climate change could alter its distribution and exacerbate its damage. In this study, we employed CLIMEX and random forest models to predict the global potential distribution of this pest based on its host Cupressus, under both current and future climate scenarios, thus quantifying the impacts of climate change. Under future climate projections, the total suitable area is expected to expand. Its native habitat is projected to experience significant northward expansion, posing a major challenge for forest management. Our predictions provide crucial evidence for the current and future global potential distribution of P. cupressi, serving as an important reference for identifying regions susceptible to potential infestation by this pest.

Phloeosinus cupressi Hopkins is an invasive bark beetle that poses a serious threat to Cupressus trees, with potential ecological and economic impacts globally. Native to North America, it has spread to Australia and New Zealand, and climate change may further alter its range. Global trade increases the risk of spread, highlighting the need for predictive modeling in management. In this study, we employed CLIMEX and random forest (RF) models to project the potential global distribution of P. cupressi, incorporating host distribution data for Cupressus. Climatic suitability is concentrated in temperate, subtropical, and Mediterranean zones, including Europe, the U.S., South America, China, Australia, and New Zealand, totaling 10,165.22 × 104 km2. Coldest-quarter precipitation (bio19) and annual temperature range (bio7) were identified as the most influential variables. Under RCP6.0 scenarios, suitable areas are projected to expand northward, increasing by ~18%. Regional shifts include contraction in southern Europe and South China, expansion in southern Argentina, southeastern Australia, and coastal New Zealand. Temperature sensitivity is expected to exceed precipitation, enhancing colonization. Due to global Cupressus trade, quarantine and monitoring should focus on high-risk regions. Our findings support early detection, long-term monitoring, and control measures for managing P. cupressi under climate change.