Climate change impacts on insect pests associated with Sitka spruce

This project aims to investigate what the potential effects of a changing climate, particularly increased temperatures, might have on the population dynamics of the insect pests associated with the UK’s most widely planted conifer tree species, Sitka spruce. By establishing experimental plots over a range of elevational gradients (and hence temperature/climatic gradients) in Sitka spruce forests in Wales, and by using a variety of insect trapping techniques, the current project will investigate how indigenous pests of Sitka spruce are likely to respond to projected changes in temperature and precipitation.

Research objectives

The key objectives are to identify the influence of temperature and precipitation on:

  • Bark beetle population dynamics, particularly abundance and population densities, timing of emergence and flight periodicity.
  • Other insect pests of Sitka spruce, particularly defoliating insects including the primary pest of Sitka spruce, the green spruce aphid ( E. abietinum), along with sawflies and Lepidoptera pests (e.g. Epinotia spp.).
  • Response of natural enemies, particularly those associated with the green spruce.

Results so far

The first year of insect sampling (2013) revealed that most insect pests associated with Sitka spruce were higher at lower elevations than at higher elevations. However, natural enemy populations were also higher at the lower elevations in 2013, and this may have an impact on pest insect populations in subsequent years. The second year of insect sampling (2014) has just been completed and the insects collected are currently being identified and the data collated.


This project started in 2012, and the first year of insect sampling was undertaken in 2013. The project is due to be completed in 2016-17 when three consecutive years of insect sampling and the processing of the material have been concluded.

Related Resources

Impact of pests and pathogens under changing management  

Impact of insects on tree growth

Combating climate change – a role for UK forests

Biosecurity Programme Board


Dr David Williams

Funders and partners

This research is currently funded by the Forestry Commission under the programme, Advice and Scientific Support for Tree Health

Forestry Commission policy
This research underpins the evidence base for the delivery of healthy and resilient forests and wider ecosystems which is part of the Tree Health and Plant Biosecurity Action Plan