Control of Aedes dorsalis with sustained-release methoprene pellets in a saltwater marsh

The efficacy and persistence of sustained-release methoprene (Altosid) pellets were evaluated in a tidal, saltwater marsh primarily against Aedes dorsalis. Pellets were applied prior to marsh inundation at 3.4 kg/ha. They provided > 99% control through the July and August high tide series (up to 42 days posttreatment), 86.4% control during the November high tide series (131 days posttreatment) and 66.6% control during the February high tide series (240 days posttreatment). Proportions of partially emerged adults increased over the course of the study, constituting 0, 0.7, 16.2 and 18.9% of the unsuccessfully emerging mosquitoes in July, August, November and February, respectively. Sixty-six percent of the completely emerged mosquitoes from the treated region of the marsh were found dead on the water surface, compared with only 0.7% from the control region. This implies that exposure to low concentrations of methoprene impairs the ability of the completely emergent mosquito to fly.