Resistance: Understanding the impact of management agreements on reducing evolution of resistance in agriculture - sea lice management as an exemplar

点击翻译按钮获取中文摘要

Sea lice (Lepeophtheirus salmonis) are a parasite that affects the growth and performance of farmed and wild salmon, as well as decreasing their immune response, making them more susceptible to disease. Efforts to combat sea lice cost the salmon industry in Scotland an estimated £40M to control each year. Sea lice in the farmed salmon population in Scotland are managed cooperatively under agreements between managers within an area, though much of this collaboration is on a voluntary basis. Unfortunately, there are indications that sea lice are becoming resistant to current treatments, requiring managers to either increase the amount of treatment used, increase the frequency of treatment, or investigate alternative methods of integrated pest management. This bears significant extra cost and could have serious environmental consequences. In the context of this rising threat of resistance, management programs must be designed to slow the evolution of resistance, but strategic use of control agents can be complicated by the actions of other decision-makers, and by uncertainty about the levels of resistance present.Compared to terrestrial pests, little is known about how sea lice evolve resistance, but new information (under investigation by one of our team members (Dr. Sturm) under project BB/L022923/1) suggests that the mechanisms may be more complicated than expected, with at least one type of resistance transmitted only through the female line. Because of uncertainty about mechanisms of resistance, tests for resistance in sea lice are not universally reliable, and can be subject to failure if sampling of the lice is not done properly. Therefore, decision-makers managing sea lice face not only uncertainty about the actions of fellow producers, but also about the level of resistance currently present in the sea lice population.In this project, we will combine mathematical and game theoretic modelling methods with expert knowledge of sea lice and the salmon industry to build a model of sea lice evolving resistance in a setting of multiple managers making decisions about how to treat sea lice. This combination of an epidemiological model of sea lice spread with a game theoretic model of treatment use will help us understand how management agreements between managers of fish farms can impact the risk of sea lice evolving resistance to treatments, and therefore help industry bodies better build and support these management agreements. Our project team has close links to industry bodies, and includes experts in the evolution of resistance in sea lice, in game-theoretic and epidemiological modelling, in high-performance computing, and in modelling of farmed fish. Using this expertise, our project will contribute to successful sea-lice management in Scotland, impacting not only the salmon industry, but also potentially wild salmon stocks, and therefore the wider marine environment.