INSECTICIDE EFFICACY OF SPATIAL REPELLENT COMPOUND-METOFLUTHRIN AGAINST SUSCEPTIBLE AND RESISTANT STRAINS OF AEDES AEGYPTI
Spatial repellents (SR), include pyrethroid insecticides that are highly volatile at low temperatures and with high lethal activities against mosquitoes, mainly Aedes vectors of arboviral diseases. Of these SR, metofluthrin is widely used in various devices for repellent consumer products. This article reports the susceptibility status of Ae. aegypti Puerto Rico permethrin-resistant laboratory strain (PR) and Orlando susceptible laboratory strain (ORL) to metofluthrin and permethrin using the CDC glass bottle bioassay. The time-mortality relationships showed that the permethrin-resistant PR strain is highly resistant to both permethrin and metofluthrin compared to the susceptible ORL strain. The resistant ratio (RR) based on the killing time (KT) (KT50 -PR/KT50 -ORL) was 30- and 5- folds for permethrin and metofluthrin, respectively. The results also showed that the PR strain is less resistance to metofluthrin than to permethrin, with a three-fold RR (KT50 -PR-per/KT50 -PR-met). These results indicate the potential risk of developing cross-resistance of metofluthrin in permethrin-resistant mosquitoes. Integrated vector management in mosquito control should be considerate of how consumer products and field operations interact to accelerate cross resistance to pyrethroids.