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

海虱（Lepeophtheirus salmonis）是一种寄生虫，影响养殖和野生鲑鱼的生长和性能，并降低它们的免疫反应，使它们更容易患病。据估计，苏格兰鲑鱼业每年为防治海虱花费4000万英镑。苏格兰养殖鲑鱼种群中的海虱是根据区域内管理者之间的协议进行合作管理的，尽管这种合作大部分是在自愿的基础上进行的。不幸的是，有迹象表明，海虱正在对目前的处理产生抗药性，这就要求管理人员要么增加使用的处理量，增加处理的频率，要么研究综合虫害管理的替代方法。这将带来巨大的额外成本，并可能造成严重的环境后果。在耐药性威胁不断上升的背景下，必须设计管理程序以减缓耐药性的演变，但由于其他决策者的行动以及目前耐药性水平的不确定性，战略性地使用控制剂可能会变得复杂。与陆地害虫相比，我们对海虱如何进化出抗性知之甚少，但新的信息（由我们的一个团队成员（Sturm博士）在BB/L022923/1项目下进行的调查）表明，其机制可能比预期的更复杂，至少有一种抗性只通过雌性传播。由于耐药机制的不确定性，海虱的耐药试验并非普遍可靠，如果对海虱取样不当，可能会失败。因此，管理海虱的决策者不仅面临着其他生产者行动的不确定性，而且还面临着目前海虱种群中存在的抗性水平的不确定性。在这个项目中，我们将把数学和博弈论建模方法与海虱和鲑鱼产业的专家知识结合起来，建立一个在多个管理者决定如何处理海虱的情况下海虱进化抗性的模型。海虱传播的流行病学模型与治疗使用的博弈论模型相结合，将帮助我们了解养鱼场管理者之间的管理协议如何影响海虱对治疗产生抗药性的风险，从而帮助行业机构更好地建立和支持这些管理协议。我们的项目团队与行业机构有着密切的联系，其中包括海虱耐药性进化、博弈论和流行病学建模、高性能计算和养殖鱼类建模方面的专家。利用这些专业知识，我们的项目将有助于苏格兰成功的海虱管理，不仅影响鲑鱼产业，还影响潜在的野生鲑鱼种群，从而影响更广泛的海洋环境。

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.