Current: ABCD of Aphid IPM

Timescale: Initially one year 2022
Project Lead: Dr Alistair Wright
Project Sponsor: Defra and BBRO

Project Summary

The virus yellows complex (VY) in sugar beet can result in severe yield losses, as witnessed in the 2020 epidemic in the UK sugar beet crop. 38.1% of the crop was estimated to have become infested with virus yellows, and resulted in around 20% yield loss, worth over £54m. This had a direct impact upon the budget available from the industry to tackle VY, since BBRO levy receipts for the 2020/21 were £500,000 lower than the previous 5-year average.

Main Objectives

Each year BBRO delivers an aphid monitoring survey during the spring to guide growers on local aphid levels and progression of the migration. This acts as a guide for growers to monitor their crops and see if their fields have reached the population threshold for control (e.g. one green wingless aphid per four plants up to the twelve leaf stage) at which they are advised to treat the crop with a foliar aphicide. As of 2022, two aphicides are registered in sugar beet; flonicamid, sold as Teppeki by Belchim Crop Protection or Afinto by Syngenta and acetamaprid, a neonicotinoid, marketed as InSyst by Certis. Both currently offer effective control of aphids. However, they require broadacre spraying and these can potentially have indirect impacts on natural predators of aphids also on the crop. M. persicae is also known to develop resistance to insecticides and therefore these may not offer complete or long-term aphid management into the future. Considering the limitations of relying on chemical seed treatments or broad-acre sprays, and the drawbacks these pose to the environment, BBRO is keen investigate commercially adaptable IPM strategies for aphid control in future sugar beet crops. This will include the aforementioned new virus tolerant or resistant varieties, but there are other techniques which warrant investigation. These are outlined below and illustrate a range of work packages which BBRO will deliver to take advantage of the high aphid pressure BBRO’s ABCD of Aphid IPM 3 expected in 2022 to understand how we can start developing integrated aphid management approaches in sugar beet. The research is proposed as four individual work packages; A- Attractants and Alternative hosts B- Beneficial insects C- Camouflage cropping D- Deterrents and Repellents These areas will also form the knowledge exchange strategy to the UK grower base: ‘BBRO’s ABCD of Aphid IPM’ over the coming year. Using our website, podcasts, British Sugar communications and grower events we will keep growers up-to-date with the findings to ultimately produce a practicable and forward looking IPM strategy.

BBRO’s ABCD of Aphid IPM 4 Work Package A: Attractants and Alternative Hosts

The first research package capitalises on utilising an aphids’ inherent dislike of sugar beet. Trials will be undertaken to investigate alternative host crops planted either amongst or around sugar beet fields. Our VY variety assessment trials, now part of BBRO’s operation Emerald, already deploy brassica buffer strips into the design to draw away virus-carrying aphids (either naturally occurring or those used to inoculate the plots) from the trial. This approach has been successful in preventing excessive unwanted virus infection within the trials, especially in the uninoculated control plots. BBRO’s Project Goliath in 2019 was our first trial to deploy brassica attractant strips to deter virus carrying aphids from our plots spreading into non-target areas of the trial. We now intend to extend this methodology into commercial fields. To achieve this we will plant brassica attractant strips or blocks amongst sugar beet fields or margins of brassicas around the outsides of fields. By using whole-field approaches we can test the effectiveness in a commercial situation.

Work Package B: Beneficials

The value of beneficial insects in aphid management cannot be underestimated or ignored. However, our in-depth understanding of population dynamics of these beneficials for commercial aphid control is limited and warrants further investigation. We plan to procure the services of an entomologist to undertake regular field inspections on a range of fields which will serve as case study sites. All will be in fields which haven’t used neonicotinoid treated seeds. Twice weekly investigations of aphid abundance in different locations in each field will take place as well as counts of the numbers and species of beneficials. Supporting this research will also be an investigation into local plant species present. Combining this information will reveal local environmental factors which may be driving aphid and/or beneficial abundance and dynamics as well as identify species (and abundance) which host virus yellows over the winter. In autumn 2021, BBRO established several wildflower strips at farm of The Morley Agricultural Foundation in Norfolk. This site will be included into our naturally occurring beneficial assessments to see whether introducing wildflower species, such as phacelia, corn camomile and wild carrot, which support natural predators of the aphids, can enhance VY management. Replicated trials will also be conducted into the introduction of lacewing larvae into fields. Beneficial insects (some treatments including moth eggs which act as a food source for the larvae prior to aphids arriving) will be introduced at several timepoints into dedicated plots. Plants in the centre of each plot will then be inoculated with viruliferous aphids to provide an initial foci of infection in each plot with VY. This study will aim to measure VY prevalence in the plots in the autumn and impact on yield. We will gain an understanding how long the beneficials remain active and whether they could be utilised as a future, farmer-applied treatment for virus yellows control. 

Work Package C: Camouflage

BBRO undertook initial investigative work in 2020 in commercial fields which had been companion cropped with cereals which had been planted to prevent wind blow. However, it was noticeable by the end of the summer that incidence of yellowing symptoms in the cereal strips was reduced, although an uplift in yield was not always observed. In 2022 we have sought to expand our dataset and have already issued a grower guide on how to test this method on a much wider scale ( 3-camocropping-guide-final-full.pdf). Additional funding will support more in-depth assessments of yield and VY prevalence in crops in the autumn. This will take the form of additional lab diagnostics which will shed light on any changes in the proportion of each virus in the study strips as well as collection of more yield samples for better determination of any impact of using the cereal cover crop.

Replicated field trials will also be added to the project to investigate the effect of using different cereal species. Three of our research sites will host these trials which will investigate barley, wheat and rye cereal covers as well as a brassica treatment. Other approaches to the camouflaging approach could also be investigated and additional funding will look at establishing replicated trials to assess the impact of using food dyes on the soil to reduce plant-soil contrast at a range of field sites. This was tested in the autumn of 2021 by BBRO with the hopes to take advantage of the autumn aphid migration (in reality few aphids we identified). The theory is the same as for the barley camouflage as it is hoped the dyes will reduce the plant-soil contrast. Extra support will enable BBRO to invest resources to set up more of these food dye trials and see if they are a viable option to camouflage sugar beet from migrating aphids.

Work Package D: Deterrents and Repellents

This research package will investigate the use of plant-based products to deter and repel aphids from sugar beet crops. This is a novel and new area for BBRO as we have not assessed repellents in the field before. 2022 poses the perfect year for this as the anticipated influx of aphids will allow for real life testing of these strategies. Repellent strategies are often encouraged in organic horticultural settings, so scaling up the technique to a broad-acre approach might be challenging. We plan to spray or spread onto growing sugar beet crops extracts of common aphid repelling plants. This will be triggered by the first arrival of winged aphids on host-farms which will be detected through expanding the BBRO’s water pan trap network.

We will use of extracts of the following products: Lavender oil, Mint extract, Garlic extract both liquid NEMguard SC, and granules (NEMguard DE - already registered as a soil applied nematicide in sugar beet) as well as sugar beet derived products; Molasses and Raffinate. Growers must urgently be found to support this research since we need a large number of fields in virus/aphid prone areas. These growers will be paid for any loss to their crop from spraying on the plant extracts, especially if any result in phytotoxicity to the sugar beet. However, there is also urgency to test these extracts for phytotoxicity under controlled conditions first.

Outcomes / Key Message For Growers And Industry

Under review
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We are set up jointly by British Sugar plc and the National Farmers' Union.

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