Biopesticides for Africa: A model system

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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?).