Insecticide susceptibility status of Culex quinquefasciatus Say, the vector of bancroftian filariasis against temephos in Delhi and National Capital Region.

Lymphatic filariasis is the second leading cause of long-term disability in the world. In India, filariasis is endemic in 250 districts in 20 states and union territories with about 553 million people at risk of infection. Temephos is being used as a larvicide to control the population of Culex quinquefasciatus mosquito, the vector of bancroftian filariasis. The susceptibility status of Cx. quinquefasciatus to temephos in various urban zones of Delhi and the national capital region (NCR) was evaluated using the WHO standard susceptibility test kit. Results of the test revealed that the larval mortality in urban zones ranged from 2.8 to 56.5%, while that in rural zones ranged from 45.0 to 71.0%. Among the urban zones, the lowest larval mortality was recorded from Karol Bagh zone (2.8%) and highest mortality was recorded from Shahdara South zone (56.5%). In the NCR, the larvae were collected from the areas surrounding Delhi, and the larval mortality ranged from 75.0 to 87.5%. The present study indicates the possible development of resistance against temephos in the larvae of Cx. quinquefasciatus mosquitoes in some urban areas.