114 - Insecticide Dispersal Efficiency Across Varied Landscapes in Operational ULV Fogging Scenarios

Abstract: Insecticidal space spraying is the primary mode of mosquito control in the United States, as it allows for mosquito population reduction over a broad land area. Ultra-low volume (ULV) fogging, characterized by an aerosolized mist forced out of a pressurized nozzle, is a common form of space spraying. ULV fogging is influenced by many environmental and physical parameters that can affect the product’s dispersal and effectiveness. Further, spray swath, or spray area size, directly affects the level of reduction in abundance of mosquitoes post-fogging. We assessed whether the swath of ultra-low volume fogging was affected by different obstructive landscape features. We hypothesize that fogging in urban and suburban landscapes results in reduced spray swath compared to rural landscapes due to the higher density of tall and impenetrable features such as skyscrapers and residential structures. We quantified droplet dispersal following both operational and open field fogging trials with Permanone 30-30® in Maricopa County, AZ, across different landscapes. Spinning impingers were positioned using a stratified random design based on landscape feature type, with each placement controlled by positioning one impinger at a point and another 180° opposite that feature. In open field trials, spinning impingers were placed in a standard grid. We found that droplet dispersal in an operational setting, when controlled for wind direction and distance from fogging truck, was less than in an unobstructed setting. The reduction in droplet density was more pronounced at further distances (2.78x) than those nearer (2.18x) to the fogging path. Collected data show some reduction based on the effect of landscape obstructions on the deposition of insecticide droplets, and more trials are scheduled to validate this claim. These results provide valuable insight into the relationship between ULV droplet dispersal and landscape structure, informing both operational decisions and future research aimed at maximizing vector control effectiveness.