LAUSR

The oriental armyworm, Mythimna separata is a major long-distance migratory insect pest of grain crops in China and other Asian countries. Migratory flights and reproductive behavior usually occur at night, regulated by a circadian rhythm. However, knowledge about the linkages between adult flight, reproduction and clock genes is still incomplete. To fill this important gap in our knowledge, a clock gene (designated Msper) was identified and phylogenetic analysis indicated that the encoded protein (MsPER) was highly similar to PER proteins from other insect species. qRT-PCR assays demonstrated significantly different spatiotemporal and circadian rhythmic accumulations of mRNA encoding MsPER occurred during development under steady light-dark conditions of 14L : 10D. The highest mRNA accumulation occurred in adult antennae and the lowest in larvae. Msper was expressed rhythmically in adult antennae, relatively lower in photophase and higher entering scotophase. Injecting siRNA into adult heads effectively knocked down Msper mRNA levels within 72 h. Most siRNA-injected adults reduced their evening flight activity significantly and did not exhibit normal evening peak of flight activity. They also failed to mate and lay eggs within 72 h. Adult mating behavior was restored to control levels by 72 h post injection. We infer that Msper is a prominent clock gene which acts in regulating adult migratory flight and mating behaviors of M. separata. Because of its influence on migration and mating, Msper may be a valuable gene to target for effective management of this migratory insect. This article is protected by copyright. All rights reserved.