Prevalence, Symbiosis with Rickettsia, and Transmission of Tomato yellow leaf curl virus of Invasive Bemisia tabaci MED Q2 in Japan

The whitefly, Bemisia tabaci, is a notorious insect pest that transmits plant pathogenic viruses to a wide range of economically important crops. An invasive genetic group of B. tabaci, Mediterranean Q2 (MED Q2), has recently spread to Europe, USA, and Asia. In the present study, we investigated the prevalence of MED Q2 in Japanese agricultural sites and found that its distribution has expanded since it was initially detected in 2013. A polymerase chain reaction ana-lysis revealed that all MED Q2 individuals were infected with Rickettsia. Rickettsia titers increased during nymphal development, presumably in response to the nutritional needs of the host. A fluorescence in situ hybridization ana-lysis revealed that Rickettsia was densely located near Portiera-containing bacteriocytes at all growth stages. Therefore, Rickettsia may play an important role, such as supplying nutrients to the host, in cooperation with Portiera. Transfer experiments indicated that MED Q2 was as effective a vector for Tomato yellow leaf curl virus as MED Q1 and, thus, is a high-risk agricultural pest. These results provide important insights into the biology and ecology of invasive MED Q2 to effectively control its spread and minimize its impact on crops.