Aedes albopictus(Skuse) susceptibility status to agrochemical-insecticides used in durian plantating systems in southern Thailand

ABSTRACT High rates of dengue, chikungunya, and zika morbidity occur in southern Thailand. The intensive application of insecticides in orchards could impact not only agricultural insect pests, but also non-target insects, such as mosquitoes, or non-target beneficial insects. In this study, the population density and insecticide susceptibility of Aedes albopictus populations to field application concentrations of four agrochemical insecticides – cypermethrin, chlorpyrifos, carbaryl, and imidacloprid were examined. Mosquito eggs were collected from durian cultivation sites in five provinces in southern Thailand and hatched and allowed to develop to the adult stage. The study sites were categorized into three groups based on insecticide application; intensive-application of insecticides (IA), less-application of insecticides (LA), and no application of insecticides (NA). Twenty ovitraps were deployed for at least three consecutive days at each study site to collect mosquito eggs and to determine the Ae. albopictus population density then WHO tube assays being used to determine the susceptibility of adult mosquitoes to selected insecticides. This study represents the first report of the agrochemical insecticide susceptibility status of Ae. albopictus collected from durian orchards in southern Thailand. The study found that the populations of Ae. albopictus were susceptible to chlorpyrifos, but showed reduced mortality following exposure to lambda-cyhalothrin, carbaryl, and imidacloprid which is suggestive of the existence of resistance. These findings provide new insights into mosquito insecticide resistance focusing on Ae. albopictus populations and has important implications for mosquito and mosquito-borne disease control in Thailand as well as providing baseline data on which future studies can develop.