miR-252 targeting temperature receptorCcTRPMto mediate the transition from summer-form to winter-form ofCacopsylla chinensis

Temperature determines the geographical distribution of organisms and affects the outbreak and damage of pests. Insects seasonal polyphenism is a successful strategy adopted by some species to adapt the changeable external environment.Cacopsylla chinensis(Yang & Li) showed two seasonal morphotypes, summer-form and winter-form, with significant differences in morphological characteristics. Low temperature is the key environmental factor to induce its transition from summer-form to winter-form. However, the detailed molecular mechanism remains unknown. Here, we firstly confirmed that low temperature of 10°C induced the transition from summer-form to winter-form by affecting the cuticle thickness and chitin content. Subsequently, we demonstrated thatCcTRPMfunctions as a temperature receptor to regulate this transition. In addition, miR-252 was identified to mediate the expression ofCcTRPMto involve in this morphological transition. Finally, we foundCcTre1andCcCHS1, two rate-limiting enzymes of insect chitin biosyntheis, act as the critical down-stream signal ofCcTRPMin mediating this behavioral transition. Taken together, our results revealed that a signal transduction cascade mediates the seasonal polyphenism inC. chinensis. These findings not only lay a solid foundation for fully clarifying the ecological adaptation mechanism ofC. chinensisoutbreak, but also broaden our understanding about insect polymorphism.