Biopesticides for Africa: A model system

非洲农业受到一系列压力的影响，导致产量损失，其中作物害虫是一个主要问题。据估计，农作物病虫害造成全球作物损失的30%左右。传统的化学农药在保护这类作物方面非常有效，但通常价格昂贵，例如在坦桑尼亚，超过70%的农民负担不起。撒哈拉以南非洲大部分地区的情况类似。除了成本问题外，那些负担得起的农民由于缺乏适当的安全装备而面临着接触有害化学物质的风险。此外，许多化学农药危害有益昆虫，如传粉昆虫、牲畜和更广泛的环境；在欧洲，这导致了过去二十年来允许用于作物保护的化学产品数量的急剧减少。在全球范围内，特别是整个非洲，都迫切需要开发更便宜、更环保的化学农药替代品，这也是我们项目的重点。用于保护农作物的生物农药来源于植物和微生物，如真菌、细菌和病毒。它们的开发成本通常比新化学品要低得多，目前，生物农药的全球销售额估计为23亿美元，约占整个农药市场的5%，并以每年16%左右的速度增长。我们提出的研究的长期目标是在坦桑尼亚开发一种新型、廉价、有效和当地生产的生物农药（称为SpexNPV），以对抗撒哈拉以南非洲最臭名昭著的害虫之一。这种害虫是非洲粘虫蛾（Spodoptera免税）的毛虫阶段。该产品将从一种自然产生的病毒中提取，这种病毒永远存在于粘虫的自然种群中，但数量很少。虽然我们的建议必须解决粘虫- spexnpv系统特有的问题，但它可以更好地被视为一个模型系统，用于理解与新型生物农药的大规模生产、大规模应用和配方相关的通用技术和生产问题，特别是在非洲。拟议研究的总体目标是使用一个特定的宿主-生物农药系统（非洲粘虫- spexnpv杆状病毒）作为模型，探索与在非洲开发和部署一种新的生物农药相关的一些关键问题。我们将通过更好地了解开发和应用生物农药的过程来做到这一点。具体来说，我们将测试生物农药对目标昆虫的影响（例如，随着时间的推移，它会对农药产生抗药性吗？），它的肠道微生物群落（例如，这是保护还是伤害它的宿主？）以及生物农药本身的有效性（随着时间的推移，它会进化出不良性状吗？）以及利用这些知识开发新的生物防治策略的潜力（例如，我们能否设计出病毒和细菌的新组合，使生物农药更有效、更便宜？）

African agriculture is impacted by a range of stresses leading to losses in yield, of which insect crop pests are a major problem. It has been estimated that agricultural crop pests account for around a 30% loss of crops grown globally. Conventional chemical pesticides are highly effective at protecting such crops, but are generally expensive and in Tanzania, for example, more than 70% of farmers cannot afford them. It is a similar story throughout most of sub-Saharan Africa. In addition to the problems with cost, those farmers who can afford them risk exposing themselves to harmful chemicals due to a lack of appropriate safety gear. Moreover, many chemical pesticides harm beneficial insects such as pollinators, livestock and the wider environment; in Europe this has resulted in a drastic reduction in the number of chemical products allowed in crop protection over the last two decades. Both globally and across Africa in particular, there is a pressing need to develop cheaper, environment-friendly alternatives to chemical pesticides, and this is the focus of our project. Biological pesticides used to protect agricultural crops are derived from plants and microorganisms, such as fungi, bacteria, and viruses. They are often much cheaper to develop than new chemicals and, currently, global sales of biopesticides are estimated to be worth $2.3 billion, around 5% of the overall pesticides market and growing at around 16% per annum.The long-term goal of our proposed study is to develop a novel, cheap, effective and locally-produced biopesticide in Tanzania (known as SpexNPV) to combat the one of the most infamous insect pests in sub-Saharan Africa. This pest is the caterpillar stage of the African armyworm moth (Spodoptera exempta). The product will be derived from a naturally-occurring virus, which is ever-present in natural populations of the armyworm in small amounts. Whilst our proposal necessarily addresses issues that are specific to the armyworm-SpexNPV system, this can better be viewed as a model system for understanding generic technical and production issues associated with the mass-production, mass-application and formulation of novel biopesticides, especially in Africa.The overall objective of the proposed study is to use a specific host-biopesticide system (African armyworm-SpexNPV baculovirus) as a model for exploring some of the key issues associated with developing and deploying a new biopesticide in Africa. We will do so by better understanding the process of developing and applying the biopesticide. Specifically, we will test to see what impact application of the biopesticide has upon the target insect (e.g. will it develop resistance to the pesticide over time?), its gut microbial community (e.g. does this protect or harm its host?) and the effectiveness of the biopesticide itself (does it evolve undesirable traits over time?), and the potential to utilise this knowledge to develop novel biocontrol strategies (e.g. can we design novel combinations of viruses and bacteria to make the biopesticide more effective and cheaper?).