Modeling the combined impacts of host plant resistance and biological control on the population dynamics of a major pest in wheat

Authors: Rand, Tatyana; RICHMOND, COURTNEY - ROWAN UNIVERSITY

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2020
Publication Date: 3/28/2020
Citation: Rand, T.A., Richmond, C.E. 2020. Modeling the combined impacts of host plant resistance and biological control on the population dynamics of a major pest in wheat. Pest Management Science. https://doi.org/10.1002/ps.5830.
DOI: https://doi.org/10.1002/ps.5830

Interpretive Summary: Single tool approaches often fail to provide effective long-term pest suppression, such that combining several tools into an integrated management strategy is critical. Yet studies that harness the power of population models to explore the relative efficacy of various management tools and their combinations remain rare. We constructed a Leslie matrix model to evaluate the potential of crop resistance, acting alone or in combination with biological control, to reduce populations of the wheat stem sawfly, Cephus cinctus, a major pest of wheat in North America. Our model projections indicated that crop resistance reduced, but did not stop, C. cinctus numbers from increasing, suggesting that implementing multiple management tools will be necessary for longer term control of this pest. The levels of parasitism needed to stop numbers from increasing were much lower in model projections for resistant solid-stemmed compared with hollow-stemmed cultivars (22 vs 86%). Furthermore, even when accounting for the reduced levels of parasitism observed in solid-stemmed cultivars, projected population growth rates were always lower in solid-stemmed compared with hollow-stemmed wheat cultivars. Despite some empirical evidence for antagonistic interactions between resistance and biological control management, our models suggest that combining these two approaches will always pest numbers to lower levels than implementing either strategy alone. More work focused on integrating biological control into crop resistance breeding programs, and determining how these approaches affect performance of limiting pest life stages, will be important to optimize sustainable approaches to integrated pest management in this system and more broadly.

Technical Abstract: Single tool approaches often fail to provide effective long-term suppression of pest populations, such that combining several tools into an integrated management strategy is critical. Yet studies that harness the power of population models to explore the relative efficacy of various management tools and their combinations remain rare. We constructed a Leslie matrix model to evaluate the potential of crop resistance, acting alone or in combination with biological control, to reduce populations of the wheat stem sawfly, Cephus cinctus, a major pest of wheat in North America. Our model projections indicated that crop resistance reduced, but did not stop, C. cinctus population growth, suggesting that implementing multiple management tools will be necessary for longer term control of this pest. The levels of parasitism needed to curtail population growth were much lower in model projections for resistant solid-stemmed compared with hollow-stemmed cultivars (22 vs 86%). Furthermore, even when accounting for the reduced levels of parasitism observed in solid-stemmed cultivars, projected population growth rates were always lower in solid-stemmed compared with hollow-stemmed wheat cultivars. Despite some empirical evidence for antagonistic interactions between resistance and biological control management, our models suggest that combining these two approaches will always reduce population growth rates to lower levels than implementing either strategy alone. More work focused on integrating biological control into crop resistance breeding programs, and determining how these approaches affect performance of limiting life stages, will be important to optimize sustainable approaches to integrated pest management in this system and more broadly.