Behavioural plasticity of a pest species may aggravate global wheat yield loss under climate change.

Extreme heat events are expected to increase under global climate change, which may depress the abundance of most insect species, including agricultural pests. However, here our experimental observations show that the behavioural plasticity within fine-scale microhabitats, which is often neglected in pest damage and crop loss predictions, can buffer the exposure to simulated extreme high temperatures in a small pest aphid species. As expected, this buffering effect promotes aphid population growth in our lab experiments. Our model predictions further suggest that this buffering effect can aggravate pest damage and wheat yield losses globally during 1977-2017 (8.7 million tons/year, accounting for ~1.2% of global production), assuming a moderate initial pest density if no pesticides are applied. This estimated yield-loss aggravation may even worsen faster ( + 2.6% per year) than the reported increase of global wheat production ( + 2.0% per year) under warming. More than 4/5 countries may undergo increasingly aggravated losses, including most of the countries with the largest wheat production, particularly serious for less developed countries. Global food security will be greatly challenged, considering many other pest insects may also cause aggravated crop loss via buffering climate impacts through behavioural plasticity.