Effect Of The Nutritional Status Of Anopheles Arabiensis (Culicidae) On Its Susceptibilty To Dicholoro – Diphenyl Trichloroethane (Ddt)

Abstract

Tests on susceptibility to DDT 4% were carried out with adult females of Anopheles arabiensis strains from Donglola and Sennar, to investigate the effect of nutritional status of female on their susceptibility by using the WHO (world health organization) adult-test method within 60 min., 30min., 20min., and 10minutes. Different nutritional status of adult female of Anopheles arabiensis with various stages of blood feeding (single or multiple blood meals) and sugar feeding were exposed to DDT in two series of experiments. The results indicated that mean knockdown times (KT50) value for DDT 4% against An. arabiensis was (KT50 X04; 20min.) in sugar fed females; that in blood fed females was (KT50 X05; 30min.) in both strains. At exposure of 60min and 30min., regardless of pretest conditioning (blood and sugar fed), females were found completely susceptible to DDT in Dongola and Sennar strains of An. arabiensis. Susceptibility decreased when the females exposed to DDT 4% for 20min. and 10min. There was significant difference (P < 0.05) in the susceptibility of blood fed An. arabiensis females on one hand and that of sugar fed An. arabiensis females on the other hand when they exposed for 10min. to DDT. The susceptibility of An. arabiensis decreased very rapidly when females fed on blood prior the test at 10 min. exposure time. Previously 24 hour blood fed and multiple blood fed females exhibited high resistant to DDT. Filial generations (one, two …) from An. arabiensis females previously fed on blood (single or multiple) showed steadily increase in resistance. In this connection, Dongola and Sennar give similar trends. The number of eggs oviposited by the treated females and egg hatchability decreased with successive generation. Adult longevity or survival decreased after exposed to DDT, this, however, increased with successive generation