Nutrient-specific foraging and the role of spiders as biocontrol agents.

蜘蛛是谷类作物中蚜虫（和其他害虫）的主要捕食者，是低投入和有机农业中害虫控制的重要组成部分。然而，它们对农民的经济价值受其密度和对害虫和非害虫的相对捕食率的影响。在实验室中已经证明，捕食者可以通过特定营养的觅食来平衡他们的饮食（Mayntz等人，Science 2005）。因此，如果它们一直在吃富含糖分的蚜虫，它们可能会优先增加对富含蛋白质的线虫或苍蝇的捕食。蜘蛛不能单靠蚜虫生存，农学家需要在作物中保存非蚜虫猎物的必要性方面得到指导。然而，营养特异性觅食从未在该领域得到证实。我们的目的是比较蜘蛛可以得到的东西和蜘蛛吃的东西。将分析常见猎物的主要营养物质（例如Hawley等人，PlosOne 2014）。我们将使用分子方法分析蜘蛛的饮食，然后将可用的食物与食用的食物进行比较，寻找平衡它们营养摄入的随机喂养的偏差。根据野外猎物密度和蜘蛛的饮食，中观实验将证实是否营养特异性觅食，而不是其他因素，正在调节猎物的选择。第一个轮转项目-形态和分子鉴定。该博士学位要求具有相关物种的分类学和分子鉴定方面的专业知识。识别蜘蛛和“困难”的猎物群体需要训练。相关物种将需要DNA条形码。这些领域的培训将主要在WOCS实验室进行，由洛桑研究所的JRB（蜘蛛）和威尔士国家博物馆的分类学家协助。第二个轮岗项目——猎物营养成分分析。博士课程的主要内容是分析主要营养物质对猎物选择的影响。学生将学习如何在CTM的指导下进行生化分析。他/她将分析来自耕地的有关物种，确定它们的营养含量以及作物和季节的影响。

Spiders are major predators of aphids (and other pests) in cereal crops and are an essential element of pest control in low-input and organic agriculture. However, their economic value to farmers is affected by their density and relative predation rates on pest and non-pest insects. It has been demonstrated in the lab that predators can exercise nutrient-specific foraging to balance their diets (Mayntz et al., Science 2005). Thus, if they have been eating sugar-rich aphids they may preferentially increase predation on protein-rich Collembola or flies.Spiders cannot survive on aphids alone and agriculturalists require guidance on the need to preserve non-aphid prey within crops. However, nutrient-specific foraging has never been demonstrated in the field. Our aim will be to compare what is available to the spiders with what the spiders have eaten. Major nutrients will be analysed for common prey (e.g. Hawley et al., PlosOne 2014). We will analyse diets of spiders using molecular methods then compare what is available with what is eaten, looking for deviations from random feeding that balance their nutrient intake.Mesocosm experiments, informed by prey densities in the field and spider diets, will confirm whether nutrientspecific foraging, rather than other factors, is regulating prey choices.First rotational project - Morphological and molecular identification. This PhD requires expertise in the taxonomy and molecular identification of the species involved. Identification of spiders and 'difficult' prey groups will require training. Relevant species will need DNA barcoding. Training in these areas will primarily be in the lab of WOCS, assisted by JRB at Rothamsted (spiders) and taxonomists in the National Museum of Wales.Second rotational project - Analysis of prey nutrients. A major element within the PhD will be analysis of the effects of major nutrients on prey choice. The student will learn how to conduct the biochemical analyses needed, supervised by CTM. S/he will analyse relevant species from arable fields, establishing their nutrient content and the effects of crop and season.