Improving food safety by reducing pesticide residues: developing a pheromone alternative to insecticides for control of thrips on legumes in Kenya

豇豆在英国很少被食用，但它是撒哈拉以南非洲地区的主要作物，据估计，那里有3800万户家庭（1.94亿人）种植豇豆，每年收获600万吨。豇豆主要由小农种植，是负担不起肉类、鱼类或奶制品的城乡贫困人口的重要蛋白质来源。不幸的是，许多小农在努力控制害虫的同时过于频繁地使用化学杀虫剂，因此供国内消费的作物往往含有高得令人无法接受的农药残留。相比之下，出口到欧洲的农产品被要求含有最少的残留物，因此获得无农药农产品是不公平的。在肯尼亚，豇豆的主要害虫是豆花蓟马，这是一种非常小的昆虫，繁殖速度快，对许多杀虫剂有抗药性。小农最终反复喷洒杀虫剂，小农的这种误用和过度使用对当地消费者产生了负面影响，特别是因为豇豆是一种主食。该项目的目的是为管理肯尼亚豇豆和其他类似作物中的豆花蓟马提供一种杀虫剂的替代品。这将减少农药的使用量，从而提高食品安全。它还将带来更高的产量，更好的农场工人的安全，减少对环境的影响和更可持续的农业。雄性蓟马聚集在一起交配。它们通过释放特殊的化学物质（信息素）来吸引雄性和雌性。我们之前在豆花蓟马中发现了两种雄性产生的化学物质，初步实验表明它们吸引雄性和雌性。我们将合成这些化学物质，然后在实验室和农作物中进行测试，以了解它们如何影响蓟马的行为。然后，我们将以多种方式利用信息素来开发一种控制豆花蓟马的方法。将开发利用信息素吸引大量的蓟马到粘性陷阱进行大规模诱捕，并扰乱和阻止交配。我们将测试的另一种方法是使用信息素将蓟马从作物吸引到可以喷洒杀虫剂的地方。尽管这种方法仍然使用杀虫剂，但使用量要少得多，而且不喷洒在作物上，避免了农药残留。我们还将开发一种称为“引诱和感染”的信息素的使用方法，我们将把蓟马吸引到一个装置上，在这个装置上，蓟马会吸收一种自然产生的真菌的孢子，这种真菌会杀死蓟马。然后，蓟马与孢子一起扩散，并将它们传播给作物上的其他蓟马。这项研究将涉及英国基尔大学和哈珀亚当斯大学的研究人员，他们将与肯尼亚国际昆虫生理学和生态学中心（icipe）的研究人员合作。这将建立肯尼亚蓟马研究的能力，并为肯尼亚和英国之间的学生实习和交流提供机会。

Cowpea is rarely eaten in the UK, but it is a major crop across Africa south of the Sahara, where it is estimated that 38 million households (194 million people) grow it and harvest a total of 6 million tonnes per year. Cowpea is mainly grown by smallholder farmers and is an important source of protein to the urban and rural poor who cannot afford meat, fish or milk products. Unfortunately, many smallholder farmers apply chemical insecticides too frequently while struggling to control pests, so that crops for domestic consumption often contain unacceptably high levels of pesticide residues. In contrast, produce for export to Europe is required to have minimal residues, so access to pesticide-free produce is not equitable.The main pest of cowpea in Kenya is the bean flower thrips, which is a very small insect that breeds fast and is resistant to many insecticides. Smallholders end up spraying the crop repeatedly with insecticides, and this misuse and overuse by smallholder farmers has negative consequences for local consumers, particularly as cowpea is a staple food.The aim of the project is to provide an alternative to insecticides for managing the bean flower thrips in cowpea and other similar crops in Kenya. This will reduce the amount of pesticide used and so improve food safety. It will also lead to higher yields, better safety for farm workers, reduced environmental impact and more sustainable agriculture.Male thrips form aggregations for mating. They do this by releasing special chemicals (pheromones) that attract males and females. We have previously identified two male-produced chemicals in the bean flower thrips and preliminary experiments show that they attract males and females. We will synthesise these chemicals and then test them in the laboratory and in crops to understand how they affect thrips behaviour. We will then exploit the pheromone in various ways to develop a control method for the bean flower thrips. The use of the pheromone will be developed to attract large numbers of thrips to sticky traps for mass trapping and to disrupt and prevent mating. Another approach we will test is the use of the pheromone to attract thrips away from the crop to areas that can be spot-sprayed with insecticide. Although this still uses insecticide, it uses far less and it is not sprayed on the crop, which avoids residues. We will also develop the use of the pheromone for a method known as "lure and infect" in which we will attract thrips to a device where the thrips pick up spores of a naturally occurring fungus that kills thrips. The thrips then disperse with the spores and spread them to other thrips on the crop. The research will involve researchers from Keele University and Harper Adams University in the UK, working with researchers from the International Centre of Insect Physiology and Ecology, known as icipe, in Kenya. This will build the capacity for thrips research in Kenya and provide an opportunity for student placements and exchanges between Kenya and the UK.