Res. Popul. Ecol. (1985) 27, 171-184. ~) by the Society of Population Ecology LIMITATION OF REPRODUCTION BY FEEDING CONDITION IN A CARABID BEETLE, CARABUS YACONINUS Teiji SOTA Entomological Laboratory, College of Agriculture, Kyoto Un;versity, Kyoto 606, Japan INTRODUCTION In many arthropod predators, the rate of potential population growth will be limited by food consumption, which will influence developmental rate, survival and adult fecun- dity (e.g. ANDREWARTHA and BrotH, 1954; HASSELL, 1978). Especially food consumption during the reproductive period directly determines egg production. Previous experi- mental studies have examined predator's reproduction at various prey densities or at various levels of food supply (e.g. DIXON, 1959 for a lady beetle; TURNBULL,1962, KESSLER, 1971, Suzum and KIRITANI, 1974 and WISE, 1975 for spiders; HORI, 1982 for a tiger beetle; MATSURA and MOROOKA, 1983 for a mantid). Generally, the number of eggs laid by predators increases proportionally with the amount of food consumed. Evaluation of the feeding condition of arthropod predators in the field has been attempted: e.g. MIYASHITA, 1968, ANDERSON, 1974 and HUMPHREYS, 1975 for spiders; MATSURA et al., 1975 for a mantid; LAWTON, 1971 for a damselfly during the immature period of the predators, and EISENGERGet al., 1981 and MATSURAand NAOAI, 1983 for mantids; HUMPHREYS, 1975 for a spider during the reproductive period. However, quantification of feeding rates in the field is difficult, and has been a challenge in popula- tion studies of arthropod predators. This paper concerns the extent to which the quantity of food may limit the reproduc- tion of the polyphagous carabid beetle, Carabus yaconinus BATES. In carabid beetles, a direct influence of the amount of food on egg production has been shown experimentally (e.g. MOLS, 1979; HEESSEN, 1980; VAN DIJK, 1983), and limitation of food in the field has been suggested (e.g. LENSKI, 1982, 1984; VAN DIjK, 1983). In this study, I reared the carabid beetles at some different feeding conditions in the laboratory and examined the effects of amount of food consumed on body weight, egg production and survival. On the basis of the experimental results, the rates of food consumption and egg production of female beetles are estimated in the field. MATERIALS AND METHODS The species Carabus yaconinus BATES iS a wingless species of ground beetle (body length: 22- 30 mm). The adults reproduce from April to early summer in the year next to their