No simple answers on future problems with pest insects

The study was recently published in the journal Frontiers in Ecology and the Environment.

That the climate is warming is shown by countless studies across the globe, and a common fear is that warming climates will lead to more damage from insects on plants. For example, the area of damaged arctic birch in Northern Scandinavia has increased significantly during the last decades, and this can partially be explained by increasing winter survival and range expansion of two species of moths, the winter moth (Operopthera brumata) and the autumn moth (Epirrita autumnata).

An international research team studied about 30 of the globally most detrimental pest insects and for almost all of them, the researchers indeed found that damage also increased, as expected. These include for instance the European spruce bark beetle (Ips typographus) and the bird cherry-oat aphid (Rhopalosiphum padi), two well-known pest insects in Northern Europe.

But quite surprisingly, for over half the species the researchers could find examples of both increased and decreased damage, but in different part of the species range. This is seen for instance for the hemlock wooly adelgid (Adelges tsugae) in North America, where damage is increasing in the northern part of the range, and decreasing in southern parts of the range.