Factors affecting intra- and interspecific variation of impacts by alien forest insects

Forests face increasing pressure from climate change, extreme climatic events and biological invasions. Alien insects can alter forest structure and functioning, but their impacts vary considerably. Some species have relatively minor effects, while others can cause substantial ecological damage. The severity of these impacts may also differ between regions and environmental conditions.

Although the impacts of alien species have been studied extensively in many ecosystems, much less is known about the factors that determine the magnitude of impacts caused by alien insects in forests. Existing evidence suggests that impact severity may depend on a combination of species traits, host relationships, environmental conditions and management. However, previous studies have often been geographically limited or based on relatively small numbers of species, making broader generalizations difficult.

This Working Group will investigate the factors underlying both interspecific and intraspecific variation in the impacts of alien forest insects. A selected set of species representing different ecological groups, including woodborers, defoliators and sap-sucking insects, and introductions across different continents will be assessed.

A central part of the project will be the Environmental Impact Classification for Alien Taxa (EICAT), a standardized framework developed under the auspices of the IUCN for comparing the magnitude of environmental impacts caused by alien species. Existing EICAT assessments will be compiled and extended to species that have not yet been assessed.

The group will combine these impact assessments with information on species traits and phylogenetic relationships, as well as environmental and management factors such as climate, geographic region and regulation. Statistical analyses will then be used to identify associations between these factors and the magnitude of observed impacts, and to examine why the same alien species may have different effects in different places.

By bringing together international experts in forest entomology, invasion biology, risk analysis, ecology and EICAT assessment, the Working Group aims to develop a broader and more systematic understanding of what drives the impacts of alien forest insects. The results will contribute to improved prediction and management of invasive forest pests and will include an expanded EICAT database, a scientific manuscript and a policy brief on managing their impacts.