A Mechanistic Model of Drosophila suzukii Population Dynamics In Contemporary and Future Climates

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Langille, Brent Aaron Bradley
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University of Guelph

Drosophila suzukii is a relatively new threat to the soft-skinned fruit industry in North America. The presence of this pest in North America is a concern and assessing the risk of potential infestation and damage can help guide regional management strategies. In this work, I present a mechanistically-realistic population model parameterized with empirical data based on laboratory observations. The principle environmental driver of vital rates for the model is temperature though I include considerations for reproductive diapause and quality of fruit available. Relative population estimates are produced for important berry producing locations using contemporary temperature data. Southern regions appear to be most suitable for supporting high population densities due to warm temperatures throughout the year though some temperate regions also may be at risk. Understanding D. suzukii’s potential to shift in abundance and range due to changing climate is an important part of long term mitigation and management strategy. The population dynamics model is run using temperature data derived from several Global Circulation Models (CMIP5) with a range of relative concentration pathway (RCP) predictions. Mean consensus between the models suggest that without adaptation to both higher prolonged temperatures and higher short-term temperature events D. suzukii population levels are likely to drop in currently higher-risk regions. Northern latitudes may experience increased populations due to milder winter and more developmentally-ideal summer conditions though many of these regions are not currently known for soft-skinned fruit production. Finally, effective communication of model design, implementation and execution details are of genuine importance. These details are provided using a modified version of the standardized Overview, Design Concepts and Details protocol proposed by Grimm et al. (2006, 2010) in hopes that the D. suzukii population dynamics model may be used or extended by third parties. A discussion of parsimony as it relates to mechanistically-rich models in the context of modelling objectives is presented as is a brief discussion of model validation. I conclude with a “user manual” for the population dynamics model and a brief overview of a web-based version.

Drosophila suzukii, mechanistic model, climate change, population dynamics, invasive pest