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For millennia, insects and the plants they feed on have been engaged in a co-evolutionary battle: to eat or not be eaten. Until recently, the two antagonistic sides have maintained a stalemate of sorts. With climate change, however, warmer temperatures could tip the balance in favor of the insects and spell danger for crops and the farmers that tend to them.
Our research team at Michigan State University’s Plant Resilience Institute watched what happened in hotter weather when hornworm caterpillars attacked a tomato plant. The tomato lost. We saw a surprising trade-off by the plant during the heat wave: It defended itself against the caterpillars but this effort prevented it from dealing with the harmful effects of heat. This caused the plant to overheat, which strengthened the caterpillars’ hand.
A study by researchers in 2018 predicted that each degree of global warming will increase crop loss from insects by 10% to 25% because insect populations and their appetites surge in warm temperatures. Other climate-related variables, including prolonged droughts or floods, are likely to compound those losses.
But although scientists have identified these varied challenges to food production, they still don’t know much about how the combination of heat and insects will affect the plants’ built-in defense systems.