Limitation of reproduction by feeding condition in a carabid beetle, Carabus yaconinus

Abstract

Summary Effects of the amount of food consumed on reproduction of the carabid beetle, Carabus yaconinus B., were studied in the laboratory by rearing beetles at different food levels, and the feeding and oviposition rates in the field were estimated on the basis of the relationships between the amount of food consumed, body weight and egg production obtained in the experiment. The maximum amount of food consumed was 150 mg of minced beef per day. The number of eggs laid per day and the mean body weight increased with an increase in the amount of food consumed. High mortality occurred only when the beetles consumed less than 25 mg of minced beef per day. The ratio of current body weight to the minimum one just before death by starvation, W/Wmin, was used for the estimation of the rates of food consumption and egg production. The relationships between mean W/Wmin ratio, the amount of food consumed and the number of eggs laid per day were clarified. The relationships between ovary states (ovary weight and the number of mature eggs in the ovary) and W/Wmin ratio were examined for the females caught in the field. Females with higher values of W/Wmin ratio had more mature eggs. The amount of food consumed by females in the field during the reproductive period was estimated to be 50–70% of the maximum value attained in the experiment and the estimated rate of oviposition was 45–59% of the maximum rate attained in the experiment.