UC Davis Agricultural and Resource Economics

Paul Mwebaze, CSIRO and UC Davis

Hazard Modelling of Insect Invasion Risk Globally – Identifying the Relative Role of International Trade and Other Drivers

Date and Location

Thursday, May 20, 2021, 4:10 PM - 5:30 PM
Online Meeting, Zoom


The socioeconomic and biological drivers of historical global ant invasions were investigated by fitting a Cox proportional hazards model. Invasion is a function of historical trade-flows and biogeographic factors, such as climatic similarity (CS) to the native range, and individual species life history traits. The model accounts for invasions from both the native range and from previously invaded regions (i.e. “bridgehead regions”). The model was fitted using historical country-level records of the 36 most widespread alien ant species across the world during a 2012-year period (1800-2012). A model that includes imports from both native ranges and previously invaded regions performs better than the model with imports only from the native range highlighting the importance of bridgehead imports in explaining invasion risk. Our results show that including trade and CS separately as well as their interaction, performs better than using CS or trade alone. We find that cumulative imports during the decade prior to species discovery is an important predictor of invasion presumably as a result of delays between initial species establishment and discovery. A 1% increase in cumulative imports from the past decade each year increases the marginal risk of invasion for that year by about 10% on average. The relative risk of invasion also varies by species attributes, native regions of a species and by importing region. Ultimately, these results are useful for predicting invasions from and for targeting biosecurity efforts to prevent new invasions.

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