Photoperiodic control of larval development and wing form inModicogryllus sp. (Orthoptera: Gryllidae)

Abstract

The bivoltine cricket locally known as ‘Tambo-Koorogi’ (Modicogryllus sp.) hibernates as a half-grown larva, and shows a developmental response to changing as well as stationary photoperiod. At 25°C, larvae matured in about 7–10 weeks in continuous or 16 h daily light, but took 10–20 weeks or more in 14 h and shorter days. A day of 15 h exerted an intermediate effect, giving a development time of 7–17 weeks. However, an increase in daylength from 12 to 15 h in the early larval life prevented diapause, while a decrease from 15 to 12 h retarded development more than a constant 12 h day. Short-winged adults occurred only when the photophase was 15 h or shorter, and their frequency increased with decreased daylength. Although the short-winged form took longer to mature than the long-winged form under the same conditions of photoperiod, delayed growth was not always associated with brachypterism.