Susceptibility Status of Culex quinquefasciatus to Malathion in Brebes Regency, Indonesia

Abstract

Brebes Regency is a bancroftian filariasis endemic area. Culex quinquiefasciatus mosquito is accused as a vector transmitting bancroftian filariasis. The eradication of disease vector that has been widely performed in Indonesia relies on the use of malathion insecticide. The use of such insecticide in the long term might decrease susceptibility status for the targeted vector. The determination on the susceptibility status in Cx. quinquefasciatus in Brebes Regency should be pursued to monitor the insecticide use. The research was to elucidate the susceptibility status of Cx. quinquefasciatus on malathion insecticide and to review the activity of non-specific esterase enzyme Cx. quinquefasciatus that have been collected from endemic (Ketanggungan district) and nonendemic (Paguyangan district) bancroftian filariasis in Brebes, Central Java, Indonesia. The determination on the susceptibility status was performed by CDC bottle bioassay method on malathion with the diagnostic dose 400 μg/bottle. Then, the biochemical assay was conducted by performing Lee method with substrate α-naphthyl acetate to test the presence of activity on non-specific esterase enzymes. Culex quinquefasciatus mosquitos that had been collected from endemic area and non-endemic area were still susceptible to malathion; percentage of mortality is 100%. In addition, the biochemical assay showed increasing activity on non-specific esterase enzymes on both locations. This preliminary research reflects that there is decomposition of insecticides that enter the body which may lead to resistance. Therefore, further molecular research needs to be done to determine genetic mutation in Cx. quinquefasciatus in Brebes.