Climate Change Impacts Insect Populations: Temperatures and Plant Pests

Temperature makes all of the difference when it comes to insects. That's why it's more important than ever to see how climate change might affect these six-legged creatures in the future. Now, scientists have discovered that temperature-driven changes alter outbreak patterns of tea tortrix, an insect that's known as a pest to plants. The findings could have implications for pest control.

The tea tortrix is native to Japan and remains dormant during the winter months. Once temperatures warm, though, the first generation of these insects emerges all at once. Similar species exist in North America, as well, including the spruce bud moth, the grape berry moth, the light brown apple moth and the summer fruit tortrix.

"While the influence of temperature on individual-level life-history traits is well understood, the impact on population-level dynamics, such as population cycles or outbreak frequency is less clear," said the researchers in a news release.

In order to examine how tea tortrix might be affected by climate, the researchers looked at more than 50 years of data on this insect. Then they developed an independent mathematical population model that could predict population dynamics under both constant and seasonally driven temperature regimes.

"When the temperatures are high, the reproduction rate is high and the developmental rate of the tea tortrix is high," said Ottar Bjørnstad of Penn State in a news release. "The population grows very fast and becomes unstable. Above a certain temperature, the population numbers overshoot the carrying capacity and the population crashes. After a bit, another generation comes in."

The findings are crucial for understanding how to control pest populations, especially as climate warms. If researchers can predict when an insect population is most likely to emerge or peak, they can schedule ways to help keep populations low.

"Understanding the timing of generations is important because typically insecticides work only during one or two of the life stages of these pests," said Bjørnstad.

As our climate warms, the researchers predict that these cycles of infestations may be more violent and more frequent. This means that it's more important than ever to understand how these insect populations function and emerge.

The findings are published in the journal Science.