Anopheles arabiensis: abundance and insecticide resistance in an irrigated area of eastern Sudan.

The abundance of Anopheles arabiensis and its susceptibility to insecticides was studied in New Halfa, eastern Sudan, from March 1999 to June 2000. Of 4854 females anophelines collected, 4847 (99.9%) were An. arabiensis and 7 (0.1%) An. pharoensis. Female An. arabiensis were breeding throughout the year, with 2 peak densities, during the rainy (158.4 females/room/day and 84.7 larvae/10 dips) and irrigated seasons (136.8 females/room/day and 44.8 larvae/10 dips). The mean biting activity was 28.8 bites/person/ night, found throughout the night, mainly outdoors. Susceptibility of An. arabiensis to insecticides dichloro-diphenyl-trichloroethane (DDT), malathion and fenitrothion was 97.8%, 96.3% and 100% respectively. An. arabiensis is the sole malaria vector in the area and is perennial rather than seasonal.