Baseline Susceptibility and Resistance Levels of Xenopsylla cheopis and Ctenocephalides felis to DDT and Dieldrin

Abstract

Wild Xenopsylla cheopis (X.cheopis) were live-collected from the Faculty of Veterinary Medicines laboratory colonies of white mice and Mastomys natalensis captured at the University campus, Morogoro. Ctenocephalides felis (C.felis) were live-collected from young goats belonging to the Faculty of Veterinary Medicine. Both colonies were reared in captivity. Parental colonies were discarded and F1 off-springs were used as stock colonies. Experimental colonies raised from stock colonies were tested with DDT and Dieldrin, employing the standard World Health Organisation (1975) test kit. A 24 hours exposure of the fleas to 1% DDT killed 83.9% and 100% of X.cheopis and C. felis respectively. Lt_50’s with DDT were respectively 7.6 hours and 3.1 hours. Similar exposure to 0.2% Dieldrin killed 51.7% X. cheopis and 59.5% C. felis. Lt_50’s for the two species were 21.2hours and 16.6hours respectively. It was generally concluded that both populations were significantly resistant to Dieldrin and X. cheopis was potentially so to DDT. The cause of the observed resistance was attributed to wide and continuous use of chlorinated hydrocarbons in controlling pests of stored products and livestock in the area. Besides its hazards to environment and non-target organisms, Dieldrin was also ineffective for controlling flea pests and vectors in the area. Use of alternative insecticides including synthetic pyrethroids was recommended