80 - Correlating Survival Curve Analyses of CDC Bottle Bioassay Data to Pesticide Exposure Endpoints in Semi-field Environments

Abstract: The CDC Bottle Bioassay (BB) is a widely used laboratory method designed to assess the level of insecticide resistance in mosquito populations. It can be applied across various species, field- or lab-derived strains, and with a wide range of insecticidal active ingredients or formulations. While the BB is a standard tool employed by mosquito control professionals nationally and internationally, few studies have clearly established how BB results correlate with outcomes observed in semi-field or field settings. Although anecdotal evidence suggests that BB outcomes can sometimes reflect semi-field or field mortality, a consistent and standardized approach to compare these datasets is lacking. In collaboration with the Insecticide Resistance Working Group of the Northeastern Center of Excellence in Vector-Borne Diseases, we investigated the relationship between reanalyzed BB data and semi-field mortality outcomes. Using Kaplan-Meier survival analysis, we calculated mean lethal times (MLTs) for various mosquito strain/insecticide pairings from BB data. This analysis encompassed over 15 combinations for which corresponding semi-field trial data (from truck-mounted ULV spray trials) were available. Preliminary results showed that MLTs were consistent for the same strain/insecticide pairings, even when tests were conducted on different days, underscoring the robustness of this method. We then compared these BB-derived MLTs with semi-field mortality outcomes recorded at various distances and times from the ULV spray transect. A strong correlation (r = 0.78, p = 0.002) was found at one specific combination of distance and time (300 ft, 12 hours), indicating predictive potential. Comparisons of BB data to other semi-field outcomes (mortality at different distances, knockdown, etc,) will also be discussed. These findings suggest that this novel analytical approach may be valuable in forecasting semi-field or field outcomes. Importantly, because it adheres to the existing CDC BB protocol, implementing this analysis would require minimal changes to current testing procedures for mosquito control programs.