Comparison in the flight ability between the soybean pod gall midge, Asphondylia yushimai and the aucuba fruit gall midge, A. aucubae (Diptera: Cecidomyiidae)

Abstract

The flight ability was compared between a host-alternating and multivoltine gall midge, Asphondylia yushimai Yukawa and Uechi (Diptera: Cecidomyiidae) and a monophagous and univoltine congener, A. aucubae Yukawa and Ohsaki (Diptera: Cecidomyiidae) using devices with a CCD camera and an apparatus for analyzing tethered flight sounds. The total flying time of their females was more than 2 h on average. The maximum continuous flying time was nearly 10 h in A. yushimai and 5 h in A. aucubae. The speed of wing-beat stroke was higher in males than in females in the two species, being adapted to mobile flight for swarming of the males, while the lower speed of stroke enables the females to fly long distance. In particular, the larger wing size of A. yushimai females was considered to support their gentle flight for long-distance. The flying speed of A. yushimai was 22.9 m/min. The flying speed and the maximum continuous flying times indicate that the A. yushimai females carry the potential strong flight ability, i.e. continuously 13.7 km within 10 h. Besides phototaxis, A. yushimai females flew to an upward direction, indicating that they fly up to the sky after mating, which was confirmed by finding a pupa in a soybean pod gall on the 19 m high rooftop of a building. The current results were reflected well in the different life history traits between A. yushimai and A. aucubae. The long-distance flight ability of A. yushimai supports the possibility of its annual northward dispersal in northern Honshu, Japan.