Friendly fungi devour grain eating insects

Overview

Results

The team

Related information

So what's the problem?

For every loaf of bread baked, the grain from the harvested crop is first stored in barns on local farms or in huge regional grain silos. This is great news for a host of insects, as there is an ample source of food for them to feed on and reproduce amongst. This can prove to be a huge problem as not only do these pests deplete the quality of the grain, but if insects are found to be contaminating their product, farmers face having batches rejected by the market which can cost the farmer anywhere between £3-£20 per tonne.

In the UK, over 8 million tonnes of grain is stored annually and a variety of treatments are used to control pest infestations. In the most recent UK pesticide usage survey, 61% of grain stores are treated using a ‘fabric’ treatment only. This involves the surfaces within the grain store being treated while the store is empty of grain. However, the number of chemicals available for farmers to treat their grain stores is reducing. This is due to a number of factors, including legislation from the EU; food and environmental safety issues; and in some cases the insects have developed a resistance to the chemicals. The EU is currently reviewing the list of active ingredients which can be used as plant protection products, ensuring all meet modern safety standards. As a result, a number of active ingredients have been withdrawn from use. In addition, pressure from consumers for green, organic produce has also led supermarket chains to demand grain which has not been treated with pesticides. As a result, bread manufacturers which supply the supermarkets often demand higher standards than the law requires as organic bread fetches a higher price. The need for an organic, safe, natural control method is clear.

What is this project doing?

An alternative to chemical pesticides are biopesticides which use fungi as a way of controlling the insects. Using their experience and expertise of working with fungi, CABI scientists – along with scientists from the Central Science Laboratory (CSL), Exosect Ltd and Sylvan Somycel – investigated the possibility of tackling the problem by developing a new biopesticide. The current project builds on the results of a previous project whereby 10 samples of naturally occurring insect killing fungi were collected from UK grain stores. Identification showed eight of these to be the fungal species Beauveria bassiana. In laboratory trials, some strains of this fungus proved 100% effective at killing a range of beetles, moths and mites but when tested in drier environmental conditions similar to grain stores, the kill rates dropped significantly. The scientists needed to find a way of increasing the virulence of the fungus by increasing the production of fugal spores and maximising their uptake by the pests.

The current project selected the two most virulent strains of B. bassiana and looked into ways of improving their efficacy within the grain store environment. Different mass production techniques were investigated in order to improve the ability of the fungus to survive and germinate in drier environments. Different formulations were also investigated to enhance the efficacy of the fungus within the grain store. As a living organism, the fungus needs to be able to survive and replicate after being formulated and as a commercial product the fungus will need to be sold in an easily applicable formula such as an emulsion, oil or powder. So, these different mediums need to be tested to ensure they can still be effective and have a realistic shelf life. Grain stores can be made of a variety of different materials so the affect of applying the fungus to a variety of grain store fabrics over a period of time was also investigated.

Results so far

CABI researchers have found that the majority of formulations can be stored and remain effective over a period of 12 months; this is important for a potential commercial product. They have also conducted tests on surfaces which are found within the grain store. Results from these trials are promising as none had a detrimental effect on the action of the fungi. Project collaborators at the Central Science Laboratory have also carried out trials assessing the effectiveness of the fungus in a variety of conditions. These have shown very promising results indicating that the fungus can be effective within difficult dry conditions.

Current legislation is working in favour of biopesticides and their development. A new scheme set up by the Pesticide Safety Directorate is making the process for registering natural, biological pesticides easier, whilst still conforming to the strict controls to protect human and animal health, and the environment.

Through this groundbreaking work, CABI and partners hope to solve the problem of insect pests which reduce grain quality. This work will help to create a safer, natural control method which could enable high quality, organic grain to be produced around the world.

Project Manager