PARENT SESSION
Poster Session 30: Invertebrate Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Estimation of the food habits for carabid beetles using stable isotope analysis.

IKEDA, Hiroshi^*,1, KUBOTA, Kohei¹, ¹ The University of Tokyo, Bunkyo-ku, Tokyo, Japan

ABSTRACT- The food habits of carabid beetles have been revealed through breeding and field observation. With respect to larval diets, carabid beetles are carnivorous in general, and are divided into three types: insect larva feeder (feed on lepidopteran and dipteran larvae), snail feeder and earthworm feeder. Adult beetles of these three types tend to be omnivorous. Nitrogen and carbon stable isotope ratios in the animals are constant to some extent according to their trophic level, because their stable isotope ratios are detected by what they ate. Therefore, ¹³C and ¹⁵N have been used to estimate the food habits of various groups of animals. We revealed the food habits of carabid beetles in the field using stable isotope analysis. We sampled middle sized and large sized carabid beetles whose larval diets were known as insect larvae, land snails, or earthworms. In addition, insect larvae (lepidopteran larvae and maggots), land snails, slugs and earthworms were sampled as the food resource of carabid beetles. The stable isotope ratios in the adults of insect larva feeders showed that they fed on little dipteran larvae. It is suggested that they fed on herbivorous insect larvae. The food habits in adults of middle sized species seemed to be the same as larval ones. In the case of large sized species, adult food habits seemed to be different from larval ones, and could not be determined by stable isotope ratio analysis, probably because of their omnivorousness.

Key words: insect larva feeder, snail feeder, earthworm feeder