Rising temperatures could boost populations of harmful insects
Researchers have noticed a new phenomenon among moths in Finland, which could prove bad news to the country’s agriculture and forestry in the future.
Entomologists have noticed that with increasingly warm years, the number of generations that moths go through in a single season has increased.
The study is based on research on moths conducted by the Kainuu Centre for Economic Development, Transport and the Environment and the Finnish Environment Institute. The study encompassed more than two million individual moths.
The increasing number of generations that a moth population goes through in a summer is generally not seen as a problem, but the change suggests that certain harmful insects, which have previously been quite rare in Finland, might become more commonplace.
For instance, certain pests that are common in Central Europe would only need a couple of generations for their populations to reach levels that are seriously harmful notes Juha Pöyry, special researcher at the Finnish Environment Institute. Therefore, climate change could make Finland more hospitable for such pests.
The Black Arches, or Nun Moth (Lymantria monacha), which has caused damage to forests in Russia, has spread from the south all the way to Central Finland. Henri Vanhanen, who has studied the distribution of harmful insects in his doctoral dissertation.
These moths have not yet caused extensive damage to coniferous trees in Finland, but if the growing season for plants in Finland gets much longer, and if summer days with temperatures over 20 degrees Celsius become more commonplace, Finnish pine and spruce forests could suffer.
Leafy trees could also be harmed by newcomers, Vanhanen says. The Gypsy Moth (Lymantria dispar) has damaged oak trees in Central Europe, and to birch in Russia. There are fears that it might eventually settle in Finland as well.
Unwanted migration could take place within Finland as well, as species that have normally been restricted to southern parts of the country start moving north.
Juha Pöyry says that the change is already happening, although there is less follow-up information about them than there is of the moths.
The European spruce bark beetle (Ips typographus) has shown a tendency to become multi-generational in the south of Estonia and in Southern Sweden, says Pekka Niemelä, Professor of Biodiversity and Environmental Research at the University of Turku.
Henri Vanhanen predicts that the same will happen in Finland. He has worked with Niemelä and others to produce forecasts of the distribution of insects for the International Panel on Climate Change. According to the forecasts, a 1.5-degree rise in the Finnish average temperature would make it possible for the beetle to go through two generations in a single summer.
Professor Niemelä attributes the increase in the number of generations taking place in a single summer to warmer summers.
Moth researcher Pöyry will not say if the insects are reacting to warmer summers, or if the species has evolved.
The moth study is to be published in the journal Global Ecology and Biogeography.