Insecticide susceptibility status of the malaria vector Anopheles arabiensis in Khartoum city, Sudan: differences between urban and periurban areas

ABSTRACT

Vector resistance to insecticides is becoming a major obstacle to malaria prevention measures. A baseline survey was carried out in Khartoum city, Sudan, during September-November 2007, to map the insecticide susceptibility status of Anopheles arabiensis and to examine the correlation with insecticide usage in urban agriculture. Susceptibility tests were conducted in 6 sentinel sites representing urban and periurban strata of the city. Mortality rates and knockdown times were calculated for 8 insecticides on a total of 9820 specimens. An. arabiensis was susceptible to bendiocarb [98.1%], propoxur [100%], fenitrothion [100%], deltamethrin [99.8%] and lambda-cyhalothrin [99.2%]. Susceptibility rates were significantly different between urban and periurban sites for malathion [80.8% vs 56.0%], DDT [99.0% vs 95.0%] and permethrin [98.5% vs 96.3%]. The 50% knockdown times were significantly higher in periurban than urban populations of An. arabiensis for deltamethrin, lambda-cyhalothrin and malathion