RNA interference of laccase2 gene in a new model beetle superworm, Zophobas atratus Fab.

The superworm, Zophobas atratus Fab., is a large beetle allowing the physiological and biochemical studies which require microsurgery and large amount biological material. Additionally, in order to develop a molecular tool, we tested the efficiency of RNA interference (RNAi) by targeting the laccase2 that is well known essential gene for cuticle sclerotization in the beetles, red flour beetle,Tribolium castaneum, and pine sawyer beetle, Monochamus alternatus. A highly conserved partial sequence of laccase2 was cloned by using a degenerate PCR. Injection of double stranded RNA (dsRNA) into the body cavity in the postembryonic stages, in the larval stage and in the prepupal stages, showed strong suppressions of the messenger RNA levels and resulted in the lack of cuticle tanning. At the high doses of the dsRNA, mild levels of developmental delay in the pupal stage were observed. The superworm provides an excellent model system to study the physiology of beetle species allowing the use of various physiological and molecular tools.