PCR-based detection of Wolbachia, cytoplasmic incompatibility microorganisms, infected in natural populations of Laodelphax striatellus (Homoptera: Delphacidae) in central Japan: has the distribution of Wolbachia spread recently?

摘要

Cytoplasmic incompatibility is caused in various insects by intracellular infection with rickettsia-like microorganisms of the genus Wolbachia. In Japan, Laodelphax striatellus [L. striatella] shows unidirectional cytoplasmic incompatibility betweennortheastern and southwestern populations. In this study, 9 natural populations of L. striatella collected from central Japan, including the geographic boundary between the 2 cytotype populations, were analysed for Wolbachia infection by polymerase chain reaction using primers specific to Wolbachia 16S ribosomal DNA. The geographic pattern of the infection rates of the southwestern (high) and the northeastern (low or zero) populations broadly resembled that of a previous study of incompatibility. In populations which originated from the boundary regions between the southwestern and northeastern populations, the infected and uninfected cytotypes coexisted. It is suggested that in some populations of L. striatella, which formerly had been uninfected with Wolbachia, the infection property had changed to the infected. Based on these results, it is conclude that the distribution of Wolbachia-infected L. striatella populations has spread north-easterly during the last 12 years.