Browsing by Author "Baraka, Germana Thomas"

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    Susceptibility and resistance status of bed bugs against pyrethroid (permethrin) and organophosphate (dichlorvos) insecticides in Dar es salaam, Tanzania
    (University of Dar es Salaam, 2018) Baraka, Germana Thomas
    Cimex hemipterus (Hemiptera: Cimicidae) is one of the bed bug species that feeds on human blood. Bed bugs have now become the problem in most of the countries. They are very challenging and are pest of significant to public health not only in developed countries but also in most of the developing countries and around the world. Residual insecticides are the most common methods currently used for control strategies although resistance against insecticides commonly used is currently a great problem. The aim of this study was to assess susceptibility and resistance status of bed bugs against pyrethroid (permethrin) and organophosphate (dichlorvos) insecticides in Dar es Salaam. Cross sectional design was employed during the study, and a total of 200 bed bugs were used for susceptibility test during an experiment where they were exposed to 1.5m/l, 3m/l and 6ml/l of permethrin and 15ml/l, 30ml/l and 60 ml/l of dichlorvos. Generally knockdown efficiency of dichlorvos on bed bugs was (99%) higher than that of permethrin (43%) considered significantly different where U = 24.5, P = 0.0001, < 0.05. Mortality at the end of 24 hours was higher in dichlorvos than in permethrin considered significantly different with P = 0.0002, < 0.05. Bed bug resistance was noted in permethrin while there was no any sign of resistance against dichlorvos exposure. Variations in concentration was noted in permethrin, Dunn’s multiple comparison test showed significant difference among concentration P <0.001. Dichlorvos concentrations were able to kill bed bugs at the end of 24 hours. LC50 and LC95 values for permethrin were 3.36 (2.356-4.364) and 2887.39 (2886.37-2888.39) respectively, while those of dichlorvos were 7.91 (3.85-11.97) and 44.39 (40.33-48.45). The findings complement to other concurrent research conducted in various parts of the world, indicating the presence of resistance patterns in permethrin. It’s recommended that, there is a need to shift from pyrethroid use to organophosphate since the use of dichlorvos is essential due to its efficacy in causing bed bug mortality so as to avoid resistance problem. On top of that there is no need to go for higher concentrations of dichlorvos as recommended by the manufactures since LC50 = 7.91 can cause mortality to half of the population.