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

Abstract

This study examined the distributions of the pre-calling period (PCP) and the time at which calling starts in three Japanese Helicoverpa armigera populations collected from Ushimado and Souja (both in Okayama Prefecture) and Ishigaki Island (Okinawa Prefecture) in September 1996. Around 50% of the females called at night 2 (the night of eclosion of a female moth was designated at night 0), although the range of the calling occurred from night 1 to night 6. However, the distribution of the PCP was significantly different among populations. The Souja moths called significantly earlier than the Okinawa and Ushimado moths. About 75% of the Ushimado and Souja moths started calling in the last 2 h of the night while the start of calling by the Okinawa 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 lights-off) was significantly earlier than the Souja and Ushimado populations. These results suggested that there are genetic variations in the PCP and the starting time of calling among local populations of H. armigera in Japan.