Enhancing resistance to existing and emerging insect pests of UK cereals

小麦是英国农业的主要作物，受到各种害虫和疾病的侵袭。英国小麦的两种主要害虫是小麦球茎蝇和谷物蚜虫。小麦球茎蝇幼虫（幼虫）在幼苗的茎中打洞，导致主要茎组织死亡，不能产生谷物。谷物蚜虫从小麦植物的叶子和生长的谷物中吸取汁液，导致发育迟缓，也传播病毒性疾病，特别是大麦黄矮病毒（影响小麦，大麦和燕麦）。目前，必须喷洒小麦作物以保护它们免受这些害虫的侵害;然而，喷洒非特异性的杀虫剂效率低、成本高，并且由于对其他昆虫和整个生态系统的影响而对环境不利。更糟糕的是，在农民意识到问题存在之前，球茎蝇幼虫的破坏往往已经完成。气候变化的影响，这是增加平均气温与温暖的冬天，正在扩大范围和严重程度的攻击这些害虫，甚至可能导致新的害虫扩大其范围到英国。由于所有这些原因，从经济和环境的角度来看，保护小麦免受昆虫侵害的新方法的开发越来越被视为优先事项。拟议的研究方案调查了开发新的作物保护方法的三种互补方法。首先，它研究了小麦植株受到谷物蚜虫和球茎蝇幼虫攻击时的反应。这些反应中的一些将由植物组织的任何损伤产生，但其他的将是特定于被特定昆虫攻击的植物。通过分析这些反应，我们将能够确定小麦如何试图保护自己免受害虫的侵害，无论是在小麦产生的具有杀虫活性的化合物方面，还是在小麦如何识别它受到昆虫攻击方面。这些反应将与小麦植株中的基因有关。然后，这些基因可以用于小麦育种计划，以实现改善小麦防御反应的定向策略。其次，该方案调查了谷物蚜虫和小麦球茎蝇如何能够应对小麦植物使用的防御策略。已知小麦对谷物蚜虫表现出部分抗性，这是由于植物产生的化学物质。然而，蚜虫能够耐受这些化学物质，并存活下来。同样，小麦球蝇能够耐受植物防御。通过研究昆虫如何适应以小麦产生的物质为食来保护自己，这些物质是杀虫的，可以设计出对抗昆虫适应的方法。这些可以采取喷雾的形式来阻止谷物蚜虫耐受小麦防御化学品的能力（这将是特定的，对其他昆虫不会造成环境损害），或者用增加量的化合物培育小麦的策略，这些化合物在赋予抗性方面最有效，例如专门针对球茎蝇消化的抑制剂。第三，将两种新的生产杀虫化合物的策略应用于该系统。一种策略是使用抗体来阻止昆虫从肠道中摄取糖或氨基酸;这种方法已经在另一种谷类作物害虫水稻褐飞虱中取得了一些成功。第二种策略使用可以由微生物或植物产生的新型蛋白质。这些新的蛋白质是两种独立的天然成分的融合，其中一种是杀虫毒素，另一种是与昆虫肠道结合的蛋白质。虽然两种组分在单独饲喂时都不具有杀虫性，但融合蛋白被转运到昆虫循环系统，在那里它是有活性的。该方案的这一部分将导致新的环境友好型杀虫剂方法。

Wheat is a major crop in British agriculture, which is subject to attack by a variety of pests and diseases. Two of the major insect pests of wheat in the UK are wheat bulb fly and cereal aphids. Wheat bulb fly larvae (grubs) burrow in the stem of young plants, leading to death of the main stalk tissue, and failure to produce grain. Cereal aphids suck sap from the leaves and growing grains of wheat plants, causing stunting, and also transmit viral diseases, particularly barley yellow dwarf virus (which affects wheat, barley and oats). Currently, wheat crops have to be sprayed to protect them against these pests; however, spraying with pesticides which are not specific is inefficient, costly, and environmentally undesirable due to effects on other insects and throughout the ecosystem. Worse, damage by bulb fly larvae is often done before the farmer has realised the problem is present. Effects of climate change, which are increasing mean temperatures with warmer winters, are extending the range and severity of attacks by these insect pests, and may even result in new pests extending their range into the UK. For all these reasons, development of new methods for protecting wheat against insects are increasingly being regarded as a priority from economical and environmental viewpoints. The proposed research programme investigates three complementary approaches to developing new crop protection methods. First, it looks at the responses made by wheat plants when they are attacked by cereal aphids and bulb fly larvae. Some of these responses will be produced by any damage to the plant tissues, but others will be specific to plants attacked by a particular insect. By analysing these responses, we will be able to identify how wheat tries to defend itself against insect pests, both in terms of compounds wheat produces which have insecticidal activity, and in terms of how wheat recognises that it is under attack by an insect. The responses will be linked to genes in the wheat plant. These genes can then be used in wheat breeding programmes, to allow a directed strategy for improving wheat's defensive responses to be carried out. Secondly, the programme investigates how cereal aphids and wheat bulb fly are able to deal with the defensive strategies used by wheat plants. Wheat is known to exhibit partial resistance to cereal aphids, due to chemicals produced by the plants. Nevertheless, the aphids are able to tolerate these chemicals, and survive. Similarly, wheat bulb fly is able to tolerate plant defences. By studying how the insects are adapted to feeding on substances produced by wheat to defend itself, which are meant to be insecticidal, ways to counter the insect adaptation can be devised. These could take the form of a spray to block the cereal aphid's capacity to tolerate wheat defensive chemicals (which would be specific and environmentally non-damaging to other insects), or a strategy for breeding wheat with increased amounts of compounds which were most effective in conferring resistance, such as inhibitors specifically targetted towards bulb fly digestion. Thirdly, two novel strategies for producing insecticidal compounds are applied to this system. One strategy uses antibodies which block the uptake of sugars or amino acids from the insect gut; this approach has been tried with some success in another insect pest of cereal crops, the rice brown planthopper. The second strategy uses novel proteins which can be made by microorganisms, or in the plant. These novel proteins are a fusion of two separate naturally-occurring components, one of which is an insecticidal toxin, and the other is a protein that binds to the insect gut. While neither component is insecticidal when fed separately, the fusion protein is transported to the insect circulatory system, where it is active. This part of the programme will lead to new environmentally-friendly insecticide methods.