Variation of Body Size in Rice Water Weevil (Coleoptera: Curculionidae) and Its Associations with Population Biology

Life history characteristics help us to determine the ability of invasive species to establish and thrive in an exotic environment. However, so far, there have been very few reports concerning geographic variation in the body size of invasive insects and the associations between body size variation and population biology. In this study, we surveyed the geographic variation in body size of an invasive agricultural pest, the rice water weevil Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), in China. Its body size variation was found to follow Bergmann’s rule, a size cline related to latitude/altitude in which weevils tended to be larger in higher latitude/altitude localities. Moreover, using adults of different body size within populations, we also characterized the relationship between body size and some population traits of this weevil, including reproduction, food consumption, cold tolerance, and agility. The results showed that, large and mid-size adults (within populations) tended to consume more rice leaves, and larger adults also laid more and longer eggs, when compared with smaller adults. However, smaller adults appeared to have higher agility. In conclusion, body size of rice water weevil varies significantly with geography, and body size variation (within populations) may affect life history traits.