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Sensitivity analyses for simulating pesticide impacts on honey bee colonies
Kuan, C., G. DeGrandi-Hoffman, R. Curry, K. Garber, A. Kanarek, M. Snyder, K. Wolfe, AND Tom Purucker. Sensitivity analyses for simulating pesticide impacts on honey bee colonies. ENVIRONMENTAL MODELLING AND SOFTWARE. Elsevier Science Ltd, New York, NY, 376:15-27, (2018).
Sensitivity analysis of the VarroaPop+Pesticide model provides future guidance for model development. Linear sensitivity analysis reveals queen strength and forager lifespan as consistent, critical parameters for colony dynamics regardless of pesticide exposure. The relative importance of pesticide parameters is a function of toxicity and application, and can fluctuate over time as displayed in the time conditional sensitivity analysis. Adult contact LD50 and application rate became critical parameters of colony dynamics in the foliar application method simulations, whereas pollen load was the most critical toxicological parameter in the soil application method simulations. Sensitivity indices of the soil application method did not unveil critical toxicological parameters, nor did simulation results display colony dynamics that deviated strongly from the control condition. Daily time series of sensitivity values allows for detailed observation of model behavior and interactions between critical parameters. The sensitivity results will be used to guide future model applications and additional data collection efforts designed to inform sensitive model parameters. The updated VarroaPop+Pesticide model is expected to become an EPA regulatory model used for assessing exposure and risks to pollinators for the pesticide registration process under FIFRA.
We employ Monte Carlo simulation and sensitivity analysis techniques to describe the population dynamics of pesticide exposure to a honey bee colony using the VarroaPop + Pesticide model. Simulations are performed of hive population trajectories with and without pesticide exposure to determine the effects of weather, queen strength, foraging activity, colony resources, and Varroa populations on colony growth and survival. The daily resolution of the model allows us to conditionally identify sensitivity metrics. Simulations indicate queen strength and forager lifespan are consistent, critical inputs for colony dynamics in both the control and exposed conditions. Adult contact toxicity, application rate and nectar load become critical parameters for colony dynamics within exposed simulations. Daily sensitivity analysis also reveals that the relative importance of these parameters fluctuates throughout the simulation period according to the status of other inputs.