Next generation biopesticides for environmentally benign control of crop pests

农药是提高农业生产力和应对因可供耕种的土地面积不断减少而增加粮食供应的挑战的重要工具。农作物的无脊椎动物害虫，包括昆虫和其他节肢动物，如毛虫、蚜虫、甲虫、苍蝇和螨虫，以及软体动物，如鼻涕和蜗牛，如果不加以治疗，可能会导致农作物全部损失。然而，无节制地滥用化学农药对环境和人类健康的负面影响是有据可查的。在寻找新的环境友好型杀虫剂的过程中，许多研究人员已经确定了利用蜘蛛、蝎子和其他捕食者等生物天然产生的各种蛋白质和多肽毒素来控制昆虫和其他无脊椎动物害虫的可能性。这些毒素有许多优点--它们是有效的，它们的作用具有高度的特异性，对高等动物没有影响；它们也容易在环境中被生物降解。然而，将这些毒素运送到它们的作用部位--通常是在中枢神经系统--仍然是一个持续存在的问题，这阻碍了它们被用作杀虫剂；而捕食性有机体可以叮咬或叮咬猎物，将毒素引入其循环系统，目标有机体通过接触或喂养的方式传递通常是无效的。融合蛋白质技术使通常需要进入有机体循环系统才能有效的蛋白质或多肽毒素转化为口服给药时有效的杀虫剂。这是通过将毒素融合到蛋白质“载体”上来实现的，这种蛋白质“载体”能够穿过目标生物体的肠壁进入循环系统。融合蛋白在单一多肽中同时包含毒素和载体，由重组表达系统中的合成基因产生，要么用于外源应用，要么在作物中内源产生。当目标生物体摄取含有融合蛋白的物质时，融合的毒素成分由“载体”运输到循环系统；它现在能够接触到它的目标。因此，融合蛋白是诱饵或喷雾剂中的有效杀虫剂。融合蛋白技术已被开发出来，用于生产更针对目标物种的新型杀虫剂，对蜜蜂等有益生物的副作用最小。由于融合蛋白是可生物降解的，它们在环境中不会持续存在，考虑到目前对水中杀螺剂残留的担忧，这是及时的。拟议的项目旨在开发两种融合蛋白原型，已被证明对毛虫、甲虫、苍蝇和蚜虫具有杀虫活性，并对鼻涕虫具有杀螺活性，以至于与潜在客户合作，准备在商业环境中对生物农药原型进行评估。这将涉及优化生产过程，并进行配方和产品开发。同时，将积累必要的背景测试，以准备农药登记数据；这将包括评估对目标害虫的药效，以及生态毒理学和环境研究。该项目还将致力于进一步开发融合蛋白生物杀虫剂，以建立适合不同应用的产品组合。它还将研究潜在目标对融合蛋白生物杀虫剂抗药性的发展，制定管理这些产品使用的战略，以最大限度地减少有效性的损失；一系列具有不同作用模式的融合蛋白的可获得性也将是抗药性管理的宝贵资源。

Pesticides are an essential tool for increasing agricultural productivity and meeting the challenge of providing increased food supplies from diminishing land areas available for cultivation. Invertebrate pests of crops, which include both insects and other arthropods, such as caterpillars, aphids, beetles, flies and mites, and molluscs, such as slugs and snails, can cause total crop losses if not treated. However, the negative effects of unregulated use of indiscriminate chemical pesticides on the environment, and human health, are well-documented. In the search for new environmentally-friendlypesticides, many investigators have identified the possibility of using examples from the wide range of protein and peptide toxins produced naturally by organisms such as spiders, scorpions and other predators to control insect and other invertebrate pests. These toxins have many advantages - they are effective, can be highly specific in their action, with no effects on higher animals; they are also susceptible to biodegradation in the environment. However, delivery of these toxins to their sites of action - usually in the central nervous system - has remained a consistent problem which has prevented their adoption as pesticides; whereas a predatory organism can sting or bite its prey to introduce toxins into its circulatory system, delivery through contact or feeding by the target organism is usually ineffective.Fusion protein technology enables the conversion of a protein or peptide toxin which normally requires access to the circulatory system of an organism to be effective, into a pesticide which is effective when orally delivered. This is achieved by fusion of the toxin to a protein "carrier", which is able to transport across the gut wall of the target organism into the circulatory system. The fusion protein, containing both the toxin and the carrier in a single polypeptide, is produced from a synthetic gene in a recombinant expression system, either for exogenous application or produced endogenously in the crop. When the target organism ingests material containing the fusion protein, the toxin component of the fusion is transported by the "carrier" into the circulatory system; it is now able to access its targets. Fusion proteins are thus effective pesticides in baits or sprays. Fusion protein technology has been developed to produce novel pesticides which are more specific towards target species, with minimal side effects on beneficial organisms, such as bees. Since fusion proteins are biodegradable, they do not persist in the environment, which is timely in view of current concerns about molluscicide residues in water supplies.The proposed project aims to develop two prototype fusion proteins, which have been shown to have insecticidal activity towards caterpillars, beetles, flies and aphids, and molluscicidal activity towards slugs, to the point where a prototype biopesticide is ready for evaluation in a commercial setting, in collaboration with potential customers. This will involve optimising the production process, and carrying out formulation and product development. At the same time the necessary background testing for preparing data for pesticide registration will be accumulated; this will include evaluation of both efficacy towards target pests, and ecotoxicological and environmental studies. The project will also aim to develop further fusion protein biopesticides, to allow a portfolio of products suitable for different applications to be built up. It will also look at development of resistance towards fusion protein biopesticides in potential targets, to develop a strategy for managing use of these products to minimise loss of effectiveness; the availability of a range of fusion proteins with differing modes of action will also be a valuable resource in resistance management.