After-effects of Tsunami on distribution and abundance of mosquitoes in rice-field areas in Miyagi Prefecture, Japan in 2011

The Tsunami caused by the Great East Japan Earthquake on 11 March 2011 in north-eastern Japan destroyed urban and rural environments completely, including buildings, dwellings, roads, bridges, agricultural fields and natural vegetation. The after-effects of the Tsunami on the distribution and abundance of mosquitoes were studied in rice field areas in Miyagi Prefecture, Japan during June to August 2011. Adult mosquitoes were collected by traps enhanced with 1 kg dry ice and the density was compared between the "Tsunani" area and "No Tsunami" area. A total of 6,542 adults of 9 species in 4 genera were collected and the following 4 species were dominant：Culex pipiens pallens, Cx. inatomii, Cx. tritaeniorhynchus and Aedes albopictus. The high density and expanded distribution of Cx. inatomii was marked. The adult density of the former 3 dominant species was significantly higher in the Tsunami area than No Tsunami area, while Ae. albopictus was significantly abundant in the No Tsunami area. Ground pools in disaster areas contained brackish water with 0.47 and 0.21 % average salinity in June and August 2011, respectively. The percentage of water samples with mosquito larvae increased from 2.7% in June to 79.5% in August, suggesting the expansion of the larval distribution of Cx. inatomii and Cx. tritaeniorhynchus as well as Anopheles sinensis-group.