In Finland, the pine pest Panolis flammea — commonly known as pine beauty moth — is shifting its range northward to escape climate change 50 years ahead of earlier predictions, according to a study published in the Scandinavian Journal of Forest Research. The authors found that both changes in the distributions and size of the pine beauty moth are connected to higher temperatures.
In the past, researchers have predicted that this move would happen, but not so soon. “This is not unexpected since many scientists have previously predicted that some insect pests will shift their distribution range northward as a result of rising temperatures caused by climate change,” said Doctoral Researcher Alexander Pulgarin Diaz from the University of Eastern Finland. “However, what is astonishing is that this is happening 50 years ahead of earlier predictions.”
The larvae of the pine beauty moth need to feed on pine species found across Central Europe. Outbreaks sometimes occur but can be controlled with chemical insecticides. Often, these outbreaks occur together with other insect pests and diseases, and — if not controlled — they may reach thousands of hectares.
Normal distributions extend from Spain over to southern France, central Italy, and sometimes Central Europe. Outbreaks have not been reported in Finland, but they’re expected soon as conditions for their development are becoming more favourable. This is the result of increasing temperatures combined with a decline in forest health, which are consequences of climate change.
Many studies have linked temperature and the distribution of insects. To assess the distribution and size of the pine beauty population in Finland, the team from the University of Eastern Finland, Joensuu, Finland, used pheromone-based traps throughout Finland in 2019–2020. They found this insect spread all the way into northern Finland (up to 68°51’N), but its abundance was higher in warmer locations, including southern Finland. In the 1970s, its distribution limit was reported only to reach 64°N.
Given these results, the authors expected that, as climate change continues and temperatures increase in Finland, the range and population density of the pine beauty moth are also likely to increase and spread further. It may even become a common and abundant pine-feeder throughout the country. For the authors, this is vital work as understanding the effects of temperature on insect populations will allow them to predict their most likely future distribution and population dynamics.
This is similar to what happened with another major pine eater, the Nun moth (Lymantria monacha), which also has spread to large areas in Finland since 2000.
Díaz J, Melin M & Tikkanen O (2022) Thermal sum drives abundance and distribution range shift of Panolis flammea in Finland, Scandinavian Journal of Forest Research, DOI: 10.1080/02827581.2022.2060303