Activity Pattern and Reproductive Behavior of the Plum Moth Illiberis rotundata Jordan (Lepidoptera : Zygaenidae : Procridinae)

Abstract

The adult activity and reproductive behavior of the plum moth Illiberis rotundata Jordan were investigated. Illiberis rotundata is univoltine and adults emerge from May to June in western Japan. Most adults emerged early in the morning especially within 2 hours after the beginning of the light phase under the laboratory conditions. Sex ratio at emergence was approximately 0.5. Females lived for 21.1±4.5 days (Mean±SD) and males lived for 24.0±5.4 days in the laboratory, taking only water. In the field, mating behavior was mainly observed in the afternoon. Females showed a characteristic calling posture as reported in other Procridinae species. Pair-bonds usually continued until the following noon, while some were ended even two or more days after (Median=21 h 57 m, Qr=1 h 57 m). Females copulated and oviposited repeatedly. The mean number of copulation was 7.1±4.5 (range : 2-16) under the experimental conditions. Oviposition was observed during the afternoon. The number of eggs that females deposited within a day decreased slowly. Fecundity, fertility and oviposition period of females which mated freely were 563.8±150.6 eggs, 80.6±17.8% and 11.9±3.1 days, respectively. We discussed the adaptive significance of their long copulation period, comparing them with those of other Lepidoptera.