Abstract: Studies on the summer population of rice water weevil (Lissorhoptrus oryzophilus) in double cropping rice area of Zhejiang Province indicated that food condition rather than air and soil temperature or day length was the main stimuli of summer diapause of the first generation adults.Under natural conditions, the first generation adults in early rice fields never changed their reproductive diapause status even if they were caged in the paddy.However, if feeding on rice seedlings, first generation adults both newly emerged and in reproductive diapause status would normally develop their ovaries, and the reproductive diapause of the aestivating first generation adults would be over.Meanwhile, the newly emerged and the aestivating adults would develop their ovaries and flight muscles simultaneously.If the food condition was kept, their flight muscles would degenerate and oviposition would be seen.

Key words: Rice water weevil, Double-cropping rice area, Summer diapause, Stimuli, invasion duration, nutrient element, ecological stoichiometry, Cyperus malaccensis