The pre-calling period and starting time of calling by females of three Japanese populations of the cotton bollworm, Helicoverpa armigera Hubner (Lepidoptera : Noctuidae)

This study examined the distributions of the pre-calling period (PCP) and t he time at which calling starts in three Japanese Helicoverpa armigera popu lations collected from Ushimado and Souja (both in Okayama Prefecture) and Ishigaki Island (Okinawa Prefecture) in September 1996. Around 50% of the f emales called at night 2 (the night of eclosion of a female moth was design ated at night 0), although the range of the calling occurred from night 1 t o night 6. However, the distribution of the PCP was significantly different among populations. The Souja moths called significantly earlier than the O kinawa and Ushimado moths. About 75% of the Ushimado and Souja moths starte d calling in the last 2 h of the night while the start of calling by the Ok inawa moths was almost uniformly distributed in the 2nd half of the night. The start of calling by the Okinawa population (average = 5.9 h after light s-off) was significantly earlier than the Souja and Ushimado populations. T hese results suggested that there are genetic variations in the PCP and the starting time of calling among local populations of H. armigera in Japan.