Biological crop protection: a new 'slow down/speed up' strategy for aphid management

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Aphids are important insect pests of a wide range of crop plants. For crops grown outdoors, including field vegetables and arable plants, the standard way of managing aphids has been to apply synthetic chemical insecticides. Originally these were very effective, but excessive use of pesticides has caused some key aphid pests to evolve resistance. At the same time, there are concerns about the environmental impact of pesticide use, which has led to many products being withdrawn from sale. Such as the neonicotinoids. This has left farmers with few workable options for controlling aphid pests which have now become a major threat to farm production. A sustainable form of aphid management that can be used by farmers is urgently needed. To make crop protection more sustainable and less prone to resistance, it is better not to over-rely on any one intervention. Diversification of tactics can be achieved through Integrated Pest Management (IPM), a way of controlling pests by combining different, complementary control agents in an environmentally sensitive way. These should principally be biological methods that include breeding pest resistant crop varieties, the use of natural enemies such as parasitic wasps, together with 'biopesticide' products based on beneficial microbes or natural products. These crop protection tools are safe for people and the environment and so they should provide a better form of crop protection. Chemical insecticides do have a role in IPM, but they are used only when necessary in order to reduce the chances of pests evolving resistance to them. Unfortunately, because farmers have been so reliant on chemical insecticides as the principle form of pest control, there is currently no effective IPM system in place yet for the majority of aphid pests in field crops. The development of IPM has been held back by a lack of new pest control agents and the knowledge about how they interact when used together. The project involves five interlinked pieces of work. (1) Data on gene expression from multiple brassica crop types is used to identify plant lines that have a high probability of showing resistance to aphids, and this will be confirmed in experiments with aphids feeding on plants in the laboratory. The gene expression data will allow genetic makers to be developed that can be used by seed companies in their plant breeding programmes. (2) The biological basis for plant resistance to aphids is determined using a series of laboratory and field experiments. (3) Research on fungal biopesticides is done to determine how their performance is affected by the environmental conditions in the field, and also to understand how crop plant resistance affects their efficacy against aphids. (4) Complementary research looks at how different types of brassica plant, with resistance to aphids, affect the function of parasitic wasps, which are important natural control agents of aphids on field crops. (5) The interaction of resistant crops, fungal biopesticides and parasitoids are studied in the field in an IPM system. The aim of this project is to develop the new knowledge and tools needed for an IPM system for aphid pests of field crops. The work centres on the peach potato aphid, Myzus persicae, which is a pest of a wide range of crops and has evolved resistance to many commonly used insecticides. The experiments involve vegetable brassicas and oilseed rape but the intention is to extend the system to other crops (sugar beet, potatoes) in future research. The research is based on a hypothesis that brassica plants with partial resistance that slows down aphid development makes the pest more susceptible to biological control agents and speeds up control with biopesticides and parasitic wasps. The project will benefit farmers and growers and others in the supply chain. The general public will benefit from improved food security and better care of the environment.