Warming can potentially change crop pest population size and composition, consequently affecting crop production and food security. To examine warming impact on crop pests, we investigated predicted warming effect (2-4^oC) on aphid population size and composition (alate proportion), and then manipulated initial alate proportion accordingly to compare aphid colonization under ladybug presence/absence.

Warming had no effect on population size, but reduced alate proportion from 5% to 1 % and interacted with ladybug presence. Specifically, aphid outbreaks in high alate proportion happened earlier with ladybug presence, while aphid outbreaks in low alate proportion happened later without ladybugs. These results were supported by modeling. Our findings suggest that warming may not necessarily increase crop pest population, but limit their colonization by changing population composition (alate proportion), making pests more susceptible to predation. In other words, biocontrol by predators may become more promising under future warming.