Vector competence of geographic strains of Aedes albopictus and Aedes polynesiensis and certain other Aedes (Stegomyia) mosquitoes for Ross River virus.

The vector competence of geographic strains of Aedes albopictus and Ae. polynesiensis and Fiji strains of Ae. pseudoscutellaris and Ae. aegypti was assessed for Ross River (RR) virus, the etiologic agent of epidemic polyarthritis. Strains of Ae. polynesiensis from Fiji, Rarotonga, Somoa and Tahiti were the most susceptible to infection per os (MID50 less than or equal to 10(1.2) Vero cell plaque-forming units [PFU]/blood meal). Virus transmission data were variable, but all strains except the one from Fiji transmitted virus at 14 to 21 days postinfection. Shanghai and Hawaii Ae. albopictus and Fiji Ae. pseudoscutellaris were also highly susceptible to per os infection with RR virus (MID50 10(2.0) to 10(2.6) PFU). Singapore and Sri Lanka Ae. albopictus and Fiji Ae. aegypti were the least susceptible (MID50 10(4.0) to 10(4.2) PFU). With one exception, virus transmission rates for Ae. pseudoscutellaris and Ae. aegypti and the four strains of Ae. albopictus ranged from 52 to 100%. A total of 4,718 third- and fourth-instar larvae from the second gonotrophic cycle of potentially infected females were tested for RR virus in 39 pools. Infection rates in parental females ranged from 87 to 100% in Ae. albopictus, Ae. pseudoscutellaris and Ae. polynesiensis and 40 to 48% in Ae. aegypti. Virus was not isolated from larval progeny.