Assessing efficacy, exposure, and risk for insecticide drift reduction technologies

Pesticide use is often a contentious issue because of the potential for various unintended effects that they may cause. Organisms or areas unintended for their use are referred to as “non-target receptors” and may include human bystanders and residents, livestock, and terrestrial or aquatic ecosystems. There is a substantial body of knowledge regarding the factors affecting spray drift and the effectiveness of certain drift reduction technologies (DRTs). However, knowledge is still lacking on how tank mix (formulation type and formulation/adjuvant combinations) contributes to the reduction in spray drift upon application. The relationship between the drift reduction potential of a tank mix and its biological efficacy is also not well known. Additionally, exposure assessments of pesticides could be refined by incorporating more realistic exposure scenarios by including off-site spray characteristics of actual environmental concentrations. And finally, it is still unclear if pesticide drift data, generated from wind tunnel experimentation, could be substituted for more expensive field trials. To investigate the relationship between insecticide formulation type and formulation/adjuvant combinations field experiments were conducted during the summers of 2014 and 2015. Analysis of off-target deposition data suggest that formulation type has a significant effect on drift. Actual environmental concentrations were estimated from ground deposition measurements as well as rotary impingers which provided droplet size distributions at different heights and distances from the spray source. Environmental concentrations are used to estimate exposure and risk to non-target insects.