The original blog we wrote has, not surprisingly, generated some comment, particularly with respect to the suggestion of a derogation on its use on kale in wild bird cover.
Our aim was always to provide a counterview to that being put forward by some NGOs and to provide some justifiable balance to the debate. Unfortunately, there is a lot of misinformation out there. For example, not all crops we grow in this country are pollinated by insects; some are wind pollinated, such as cereals and to a large extent oilseed rape, and the oft-used statistic that 1 teaspoon of neonics would kill four lorry loads of bees is based on the LD50 exposure in laboratory conditions (the neonics’ ‘LD50’ – the dose that kills half of test subjects – in honeybees is about 4 billionths of a gram) and not the field. It makes headlines but is not constructive and does not represent reality. Likewise, we have yet to see any analysis of the impact on bees of the removal of the vast quantities of early season pollen. which oilseed rape once provided, although those closest to the issue, the beekeepers, have certainly commented.
Neonics are considered a risk to bees in the field; hence the restrictions on its use introduced in 2018. Consequently, this emergency authorization by Defra included measures to mitigate the known risk of neonics use through the exclusion of flowering crops in subsequent cultivations, the control of weeds in sugar beet using recommended herbicides, and use of the product in a “limited and controlled” way. This is not a reversal of the ban on neonics; it is merely a derogation whilst alternative means of combating the infection are sought, which can take time (see more below).
In addition, Defra’s decision statement went on to say: “The Secretary of State is satisfied there is sufficient evidence to indicate that residues of thiamethoxam and its metabolite deteriorate over time, and that with mitigation measures in place the risks are considered to be acceptably low enough that the benefits outweigh them.“
There are two points of interest here:
- The fact that residues deteriorate over time suggests that the real problem with the use of neonics historically was the widespread annual usage, which built up the environmental load and potential movement out of fields into field margins and water courses.
- The balance between risk and benefit is, in our opinion, key and why we sought to engender debate about how policy should balance objectives and the consequent value judgements needed about the inevitable trade-offs, which some seek to ignore.
Birds and insects are part of an increasingly fragile ecosystem due to pressures from human-influenced environmental changes. For example, our research has demonstrated the significance of the removal of insects due to pesticides to a range of farmland birds, as well as the impacts of the changing climate on insect assemblages. Focusing on one aspect of this complex web risks under-valuing others.
Our point about considering a derogation for kale seeks to challenge current thinking that banning a product is the best approach, without fully weighing up the cost-benefits. Research by ourselves and the BTO showed that kale is the most widely used of any seed type in wild bird cover mixes, providing an oil-rich seed. It is, however, difficult to establish in the absence of neonicotinoids as it is often decimated by cabbage stem flea beetle. By not growing it there is a potential impact on wild bird populations. It is also a biennial, flowering in the second year when it has achieved considerable size (much larger than oilseed rape) and therefore there is greater opportunity for dilution of any neonics in the plants. Likewise, there is also more opportunity for degradation in soil and therefore uptake in the second growing season.
There are also other cost-benefit issues that need considering. Product withdrawal can lead to more interventions with less effective, but possibly more damaging products. Farmers have resorted to sequential sprays of synthetic pyrethroids to control cabbage stem flea beetle (CSFB), which affects oilseed rape and kale. Most populations of CSFB are resistant or partially resistant to the spray. Yet pyrethroids are very toxic to spiders – one of the key natural enemies of CSFB – as well as other terrestrial and aquatic insects. As they are usually sprayed in the autumn when there is much rain, the risk from run-off into water is high. In addition, with early sown crops sometimes more than one foliar applied insecticide is used. The same situation applies to autumn-sown cereals. What is needed are trials to compare the alternative: neonic-treated seed versus foliar insecticides.
Removing products at short notice also causes problems because the agricultural industry doesn’t have time to devise alternative strategies or technologies. Pest-resistant varieties of crop are a perfect solution but take many years to develop. Integrated Pest Management is also an option but is part of a holistic approach that takes time to develop and to become effective. As a consequence, short-term and often more damaging measures are used.
Until such research is undertaken to compare treatment programmes or alternative ‘biological’ methods of control are proven, emergency derogations should be considered where the benefits (to food or conservation) outweigh the risks. Reducing the risks can be achieved through mitigating measures. For a kale-based wild bird mix, this might involve not including annual flowering plants, keeping weeds under control, and mixing with cereals such as triticale instead. Planting kale as part of a mix would reduce the concentration of neonics in the soil and potentially reduce exposure to bees. However, as far as we are aware no research has been done on the use of neonic seed dressings on kale used in conservation crops (which are not sown annually). Given kale’s value as a wildlife crop, we hope to fill this information gap – watch this space!