Genetic Variation in Flight Activity of <I>Ophraella communa</I> (Coleoptera: Chrysomelidae): Heritability Estimated by Artificial Selection

Abstract

The exotic beetle Ophraella communa LeSage (Coleoptera: Chrysomelidae) was first found in 1996 in Japan and has rapidly expanded its distribution. This study investigated variation in flight activity and its genetic basis in this beetle by measuring its flight time on a flight mill system. The O. communa population exhibited substantial variation in flight activity among individuals. More than 30% of the beetles did not fly at all during a 23-h experimental period, whereas 20-26% of the beetles flew for over 60 min. Bidirectional artificial selection based on total flight time (0 or > 60 min) significantly shifted the distributions of flight time and percentage of beetles flying after several generations. Repeatability of the following five flight components was analyzed: the total flight time, longest duration of single flight, mean duration of single flights, number of single flights, and a fly-or-not criterion (flying at least once [1] or nothing at all [0]) because it defines a theoretical upper limit of heritability. Among them, the fly-or-not criterion had the highest repeatability (0.797), followed by the total flight time (0.648). The fly-or-not criterion assumes a threshold trait, whereas the total flight time is regarded as a continuous trait. The realized heritabilities of these traits were estimated at 0.206-0.864 based on the threshold trait and 0.125-0.531 based on the continuous trait.