How are the niches of weed biocontrol insects likely to respond to perturbations such as climate change? How will these responses affect biocontrol effectiveness and safety? The ecological niche provides a quantitative description of the requirements of a biological control organism (e.g. host range), what it can tolerate (e.g. climatic tolerances), and possible impacts on the resident community. A deeper understanding of how niches evolve or remain conserved is crucial for answering the above questions. A prevailing view is that host and climatic ranges of introduced biological control organisms are conserved. If so, biological control organisms would respond not by niche evolution, but by local extinction, moving to higher latitudes and elevations, or plasticity in phenology. Host and habitat specificity will be conserved within the abiotic and biotic bounds set by a constant niche. However, recent research shows that some introduced biological control organisms harbor appropriate genetic variation in phenotypic traits (e.g. phenology and temperature tolerance) that can fuel rapid microevolutionary change in novel environments, leading to observable changes in the ecological niche that expand geographic ranges, realized host ranges, and environmental impacts. Findings from this research should motivate regulators to require pre-evaluation of micro-evolutionary potential of candidate biological control organisms prior to release, and we offer some methods to comply with this requirement.
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Peter McEvoy is a professor at Oregon State University. His research focuses on the ecology and biological control of invasive plant species. He is also interested in population and community ecology, ecological genetics, host-plant selection by phytophagous insects, and the ecology and evolution of life history traits.