Effects of environmental change: increased nematode pest status on UK crops.

植物寄生线虫是一种重要的经济、农业害虫。它们既直接作为取食的结果对作物造成损害，也作为疾病的病毒媒介，如在土豆上喷洒。植物寄生线虫可以归类为栖息性线虫，如马铃薯和甜菜胞囊线虫和根结线虫，或自由生活的线虫，如粗根线虫和针状线虫。杀线虫剂历来被用来控制线虫问题，但往往是广谱和相对持久的。立法已经导致最近损失了两种主要的杀线虫剂，以回应它们的使用引起的环境问题。欧盟相关指令的修订将导致剩余的三种杀线虫剂从市场上消失，获得安全替代品的前景有限。对许多英国种植者来说，失去杀线虫剂的控制和潜在的气候变化是一个可怕的情况。气候变化预计将使英国夏季气温上升2.4-4摄氏度，并改变降雨模式，夏季预计将更加干燥30%(几个气候模型的中值)。气候变化可能会导致已经在英国流行的线虫造成的经济损失增加。较高的土壤温度会增加植物寄生线虫的发育速度，导致一些线虫繁殖更多，从而对寄主作物造成更大的损害。较早成熟的马铃薯孢囊线虫可能会影响进入休眠期的第二代的比例，从而使作物在一个生长季节内更容易再次感染。甜菜孢囊线虫的世代数也可能增加。当作物还必须像土豆、甜菜和其他作物那样承受干燥土壤的非生物胁迫时，孢囊线虫的影响就会增强。气候变化可能会导致在英国流行但很少造成破坏的线虫物种成为重要的农艺害虫。土壤干燥不利于谷孢囊线虫的防治。它们通常受到真菌的自然控制，但在干燥的夏天这种抑制作用会减弱，因为它们的一些真菌敌人用游动孢子感染线虫，这些游动孢子需要高土壤湿度才能活动。这可能会对下一季谷类作物造成损害，因为越冬的谷类孢囊线虫种群数量增加。降雨量的变化也会影响那些攻击植物的自由生活的线虫。例如，高土壤湿度会增强靠近土壤表面的毛状线虫和长叶线虫的活动，导致幼苗受损，就像甜菜对接障碍一样。气温上升可能会导致更大的威胁，因为线虫物种很少有记录(但当发现大量存在时)在英国变得普遍。随着英国土壤变暖，在欧洲其他地方大量存在的外来根结线虫物种有可能成为既定的害虫。在这项工作中，线虫学家将收集气候影响建模人员所需的生物信息，以将新信息与现有信息相结合，以预测随着气候变化的继续，英国农业线虫虫害风险的增加。将利用土壤温度和水分与线虫发育、繁殖率和作物损害相关的主要数据，开发和测试英国线虫种群的模拟模型。该模型将使用二级生物数据进行精炼和测试，然后与UKCP09气候数据一起使用，以预测未来线虫发生的风险。分辨率将达到25平方公里，并与土壤类型有关。所获得的见解将用于制定虫害管理战略，以减轻线虫虫害状况变化的影响。这是必要的，因为在欧盟立法改变后，种植者不太可能像过去广泛使用的那样对线虫进行化学控制。

Plant parasitic nematodes are important, economic, agricultural pests. They cause crop damage both directly as a result of their feeding and as viral vectors of diseases such as spraing on potatoes. Plant parasitic nematodes can be classified as either sedentary e.g. potato and beet cyst nematodes and root knot nematodes, or free-living e.g. stubby root and needle nematodes. Nematicides have historically been used to control nematode problems but have tended to be broad spectrum and relatively persistent. Legislation has already resulted in the recent loss of two major nematicides in response to the environmental concerns that their use raised. Amendments to relevant EU directives will cause loss from the market of the three remaining nematicides with limited prospects for safe alternatives becoming available. The loss of nematicide control and potential changes in climate present a dire situation for many British growers.Climate change is predicted to increase summer temperatures in the UK by 2.4-4 oC and alter rainfall patterns with summers predicted to be drier by 30% (a median value from several climate models). Climate change could result in increased economic damage caused by nematodes that are already prevalent in the UK. Higher soil temperatures will increase the rate of development of plant parasitic nematodes resulting in greater multiplication of some and hence more damage to host crops. Earlier maturity of potato cyst nematodes may influence the proportion of the second generation that enters a period of dormancy, allowing greater re-infection of the crop within a growing season. The number of generations of beet cyst nematodes may also increase. The impact of cyst nematodes is enhanced when crops must also withstand the abiotic stress of dry soils as reported for potato, beet and other crops. Climate change may cause nematode species that are prevalent, but infrequently damaging in the UK, to become important agronomic pests. Dry soils are detrimental to control of cereal cyst nematodes. They are normally under natural control from fungi but this suppression is reduced in dry summers because some of their fungal enemies infect nematodes with zoospores that require high soil moisture levels for their activity. This risks damage to the next cereal crop from an increase in overwintering population levels of cereal cyst nematodes. Changes in rainfall will also impact on those free-living nematodes that attack plants. For instance, high soil moisture enhances the activity of trichodorids and longidorids close to the soil surface leading to seedling damage as in Docking disorder of sugar beet.Increased temperatures could lead to a greater threat from nematode species that are recorded rarely (but when found are present in high numbers) becoming widespread in the UK. There is a risk that alien species of root-knot nematodes, that are abundant elsewhere in Europe, can become established pests as UK soils warm. In this work, nematologists will collect the biological information necessary for a climate impacts modeller to integrate the new information with that already available to predict increased risks from nematode pests of UK agriculture as climate change continues. Simulation models of UK nematode populations will be developed and tested using primary data relating soil temperature and moisture to nematode development, multiplication rates and crop damage. The model will be refined and tested using secondary biological data prior to being used with the UKCP09 climate data to project the risk of future nematode occurrence. Resolution will be to 25km2 and be related to soil type. The insights gained will be used to develop pest management strategies to mitigate the impact of changes in nematode pest status. This is necessary given chemical control of nematodes as used widely in the past is unlikely to be available to growers following changes in EU legislation.