Further Development and Testing of a Compact Wind Tunnel for Exposing Mosquitoes to Formulated Insecticide Products

Insecticide resistance is increasing globally, and tools must be developed to combat this issue facing mosquito control programs that protect public health and inform operational decisions. Field trials to assess insecticide formulated products (FPs) are logistically demanding and weather-dependent and the Centers for Disease Control and Prevention bottle bioassays are optimized to test technical active ingredient (AI) residue, not aerosolized FP. Here, the methodological gap between AI and FP efficacy testing is addressed. The current study assessed the knockdown/mortality of laboratory and wild populations of Aedes albopictus and Culex pipiens/quinquefasciatus to four FPs (Biomist^®, Duet^®, AquaDuet^®, ReMoa Tri^®) in wind tunnel experiments. The number of FP droplets on mosquitoes was analyzed. Regression analyses showed that droplet counts on mosquitoes were significantly (p < 0.05) related to mosquito mortality for some FPs. The wild Culex population was resistant to all FPs in the wind tunnel. Here, when wind tunnel experiments resulted in a relatively low mortality rate (<90%), this indicates mosquito resistance to the FP. In these situations, a field trial would likely not achieve good results and may not be necessary. Alternatively, when wind tunnel experiments resulted in a nearly perfect mortality rate, a confirmatory field trial could be conducted, if needed.