Wireworm in potatoes and cabbage stem flea beetle in oilseed rape are two of the arable industry’s biggest pest challenges. They can result in catastrophic yields for farmers and disrupt the entire supply chain.

Both these pest problems are being tackled with a novel approach to research developed by Fera Science, which unites farmers and scientists in a collaboration with multiple industry partners to deliver practical solutions and plug knowledge gaps.

See also: Where is the crop industry with nematode biocontrols?

In 2022, Fera began Enigma I, a research and development project tackling wireworm problems in UK potato crops.

Building on its success, subsequent Enigma projects were launched, tackling issues such as tomato brown rugose fruit virus (ToBRFV) and spraing, (caused by tobacco rattle virus) in potatoes.

It is now working on Enigma V, which focuses on mitigating the impact of cabbage stem flea beetle (CSFB) and its effect on OSR.

Adam Bedford, collaborative projects director at Fera, explains: “By collaborating with industry partners, we ensure the research projects align with industry needs and that any costs are shared between partners, as is any resulting IP from the innovations we develop together.”

(1) Wireworm case study

Martyn Cox, an independent agronomist from Norfolk who works with numerous potato growers, has seen first-hand the severe impact of wireworm infestations.

“It became clear that wireworm has become major problem in East Anglia; the losses farmers were undergoing were massive,” he says.

“Both myself and the farming industry have no scientific knowledge of wireworm, so I got in contact with Fera and that’s when Enigma I was started. We had six industry partners involved from across the supply chain, including agronomists and grower groups.”

No pesticides

Wireworms are particularly destructive because there are no pesticides available to combat them.

The pest damages root crops early in the season, making it impossible to mitigate losses by harvesting early.

“To understand wireworms further, we need to understand how climate change, crop rotation practices and cover crops affect them,” says Martyn.

Since its launch two years ago, Enigma I has made significant progress.

The project brought scientists together with farmers, who together have monitored wireworm larvae and created a visual guide to identify the main species which are concerning UK producers.

 “Wireworm has always been considered as a pest, but in fact it is dependent on the species; 80% of wireworm are not pests,” says Martyn.

“I have seen lot of land that, before this research, would not have been used for potatoes.”

The threshold for wireworm is one worm in 10 traps – some land had up to 120 wireworms in 12 traps. But that particular species doesn’t cause damage, so this land was still able to be cropped.

Knowledge sharing

There have been several more key areas to the study.

Knowledge sharing workshops have been held to educate project partners on how to differentiate between wireworms, click beetles and other similar insects, empowering farmers with practical insights.

To gain a further understanding of the issue, a literature review has taken place, attempting to identify the species which are more prevalent in UK agriculture, and identifying gaps in existing knowledge data, of which there were many.  

The gaps in findings will guide future research and targeted interventions. For example, most research has taken place outside of the UK, so any life study information gathered now will take place at temperatures which are relevant to the UK.

A geographical map illustrating wireworm distribution has also been developed, overlayed with soil temperature and moisture levels, and including predictions for 2040.

“By understanding the potential spread of these pests, both farmers and researchers are able to source measures to cope,” says Martyn.

“It has been remarkably rewarding and we have made a phenomenal amount of progress in such a short amount of time.”

Martyn is now beginning the second part of Enigma I, seeking new collaborations and partners within the industry.

(2) Cabbage stem flea beetle

Cabbage stem flea beetle is a pest that primarily affects brassica crops such as OSR, cabbage and other cruciferous plants.

It has become a significant problem for OSR growers, with 2024 marking the lowest OSR planted area in 40 years, according to the AHDB.

“It was a huge problem in East Anglia, but due to climate change its territory is spreading further north than ever before,” says Hannah Fenton, a senior scientist at Fera and project manager of Enigma V.

“Previously farmers could use neonicotinoids to control the pests, but when these were withdrawn in 2013 there was a reliance on pyrethroid insecticides.

“Unfortunately, due to overuse and lack of alternatives on the market this has led to resistance in beetle populations, making these insecticides less effective.”

Cabbage stem flea beetle in oilseed rape © Fera

Because of this resistance, farmers are now struggling to protect their crops and are producing smaller yields as a result.

Not only does this mean that the profitability of OSR is dropping, so is its overall viability.

And this not only affects growers, but the wider landscape, with OSR needed for both oil production and livestock feed.

This is where the project’s partners, including United Oilseeds, Frontier, Limagrain, ADM and PepsiCo, come in, as it is in their best interest for yields to improve.

“Even if we did set out with trying to find an effective treatment for CSFB, the optimum result is just to identify a way for yields to improve again,” says Hannah.

How CSFB affects the crop

OSR is most vulnerable at emergence, and this is when adult flea beetles damage the growing point of the crop; as soon as the cotyledons emerge the beetles feed on them, which can cause entire crop failure.

“Even if the plant is able to develop, the beetles’ offspring then hatch out and burrow through the stems. By this point the plant is more resilient to damage and can still produce a crop, but the yields are not what they could have been,” she says.

Hannah, who studied a PhD in pesticide resistance, is hopeful that her research will benefit farmers.

“As it is the farmers and the wider supply chain that this will be affecting, to me it is important that the project is led and directed by them,” she notes.

Botanicals

Laboratory trials demonstrated that botanicals can improve the efficacy of synthetic pyrethroids and reduce the amounts of pesticide required for effective control of CSFB.

The aim of the Enigma V project is to evaluate whether this can be transferred to the field.

“My main aim is to see if we can improve control of CSFB, but also reduce pesticide application. The botanicals are natural products, which are not as persistent as synthetic pesticides and, therefore, may be less harmful to the environment.”

While initial tests are now being conducted in a glasshouse setting, successful results could lead to field trials.

“It is not going to be a silver bullet, but we hope this work and the results will be part of an integrated approach to managing CSFB, alongside other methods such as earlier drilling times to improve establishment and intercropping.”