Biologist Delta Mosquito and Vector Control District, California, United States
Abstract: Delta Mosquito and Vector Control District (DMVCD) has traditionally relied on property inspections to control Aedes aegypti (L.) populations through source reduction of mosquito breeding sites. While effective, this method is time consuming, labor intensive, and heavily dependent on resident cooperation. In recent years, DMVCD has been implementing an areawide larviciding strategy in suburban neighborhoods, tracking adult mosquito populations before, during, and after applications, to assess its impact. In this study, we selected six sites with historically high Ae. aegypti abundance and similar population dynamics. Two sites were treated in May as early intervention during the mosquito’s lag growth phase (weeks 19-22), two sites were treated in June as regular intervention at the beginning of the exponential growth phase (weeks 23-26), and two sites remained untreated as controls. At the treatment sites, Altosid SR-20 was applied at a rate of 0.75 oz per acre using a truck-mounted A1 Super Duty Sprayer with a 150-foot swath width. Applications were conducted weekly for four consecutive weeks for each intervention. Mosquito abundance was monitored at all six sites using BG-Sentinel traps, with five traps deployed per site for a total of 30 traps, each baited with dry ice. Trapping started 2 weeks prior to treatments and continued weekly until 2 weeks after the last treatment. Both treatment interventions showed measurable reductions in adult mosquito counts compared to untreated control sites. The early intervention sites exhibited a statistically significant decrease compared with the other groups; however, this effect may be temporary, as a rebound in mosquito counts was observed across all sites. This study is preliminary and will need further improvements, but it does potentially offer an effective method of treatment for Ae. aegypti.
