Soybean aphids, Aphis glycines Matsumura, seriously impact soybean production. Warming may enhance aphid population growth, yet it may also reduce alate (winged) aphids, potentially impeding aphid colonization. This study examined how climate warming (2 – 4^oC) may affect the population growth and colonization of soybean aphids currently living near their optimal temperature.

We first conducted a laboratory experiment, examine warming impact on aphid population size and structure (alate proportion). We then set up a field colonization experiment, examining how warming impact on aphid population size and structure may consequently affect aphid colonization with ladybugs (predators; biocontrol). The results showed that warming reduced alate production, but had no effect on overall aphid population size, suggesting that warming could change pest population structure without affecting pest population size. Ladybugs failed to control aphid colonization under high alate proportion (ambient scenario), but succeeded under lower alate proportion (warming scenario). Our results imply that warming may limit soybean aphid colonization, by reducing the production of alate aphids and facilitating the biocontrol by ladybugs.