Factors affecting flight activity of Ophraella communa (Coleoptera: Chrysomelidae), an exotic insect in Japan.
The exotic beetle Ophraella communa LeSage was first found in 1996 in Japan and has rapidly expanded its distribution. This study examined the effect of several factors on the flight activity of this beetle and estimated its dispersal potential by measuring its flight time on a flight mill system. The beetles exhibited low flight activity at the age of 1-3 d posteclosion; however, after 4 d, it increased and thereafter remained high. The beetles reduced flight activity under the dark photophase, although they flew during both light and dark phases. Flight activity was lower in adults reared from hatching under a 12:12 (L:D)-h photoperiod than in those reared under a 16:8-h photoperiod; the shorter photoperiod was found to induce reproductive diapause. This photoperiodic response could explain seasonal changes in flight activities in which fourth-generation adults displayed the lowest activity before overwintering. The female beetles flew, at maximum, for 385 min during a 23-h experimental period. Based on this value, the flight distance was estimated to be 25 km/23 h, suggesting a high dispersal potential of this beetle.