Influence of the Distribution of Host Species on Adult Abundance of Japanese Encephalitis Vectors Culex Vishnui Subgroup and Culex Gelidus in a Rice-cultivating Village in Northern Vietnam

A field study was conducted in a village in northern Vietnam to investigate how host distribution influences Japanese encephalitis (JE) vector abundance. Indoor and outdoor collections were conducted from 50 compounds. We collected three JE vector species--Culex tritaeniorhynchus and Culex vishnui that comprised the Culex vishnui group, and Culex gelidus. Spatial autocorrelation was not observed in the mosquito assemblies at any scale larger than the house compounds. Multivariate analyses revealed that the Cx. gelidus density correlated positively with both the host proximity to the breeding sites and cattle density; however, the Cx. vishnui subgroup density correlated positively only with cattle density. These results showed that the number of cattle in a compound influenced the JE vector abundance in that compound, and the abundance of Cx. gelidus, not of the Cx. vishnui subgroup, was affected by the host proximity to the breeding sites in the village.