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Sulfoxaflor, a Not so Bee-Friendly "Alternative"

With overwhelming evidence on the risks that neonicotinoids, mainly Clothianidin, Imidacloprid and Thiamethoxam pose to bees, phytopharmaceutical companies look towards innovation to replace already banned or restricted insecticides. Promoted as a "safer" option and a "replacement" for other neonicotinoids, Sulfoxaflor is presented as one of the possible alternatives. This insecticide of the sulfoximine family, like previous neonicotinoids, attacks the central nervous system of insects, sometimes even those who are non-targeted [1]. A recent study found that this alternative might not be as safe as previously promoted [2]. Besides, we recall that sulfoxaflor might not even be considered as an alternative, but a part of a new generation of neonicotinoids [3].

After legislation changes on neonicotinoids, including this year's ban on all open air uses of three neonicotinoids in the EU [4], the sulfoximine family seemed to be the rightful heir of the systemic insecticides throne. Commonly exemplified by Sulfoxaflor, these insecticides have certain different structures than neonicotinoids. It targets sap-feeding insects, aiming to surpass an already proven resistance of some insects to several neonicotinoids. The evidence supports the efficacy of Sulfoxaflor, against which insects have a considerably reduced resistance [5].

However, efficacy can only be a part of the description of this insecticide. As its proven performance against sap-feeding insects attracts the market and farmers around the world, it also raises concerns. A recently published study has determined that Sulfoxaflor can have a negative impact on non-targeted insects, bumblebees. After exposure to the insecticide, bumblebee colonies "produced significantly fewer workers than unexposed controls, and ultimately produced fewer reproductive offspring". Exposed colonies had a significant decrease in the production of queens and males, reaching decrease rates up to 54% when compared to control colonies [6].

The study conducted at the Royal Holloway University of London used dosages consistent with post-spray field exposure. Already providing evidence of the dangers that the insecticide may cause to bees. Previously, the European Food Safety Authority had already determined that a high risk to bees could not be excluded [7]. Thanks to this recent study, evidence continues to point towards a need for closer review of new systemic insecticides.

Media coverage of the situation has been extensive, featuring the story in major news outlets such as BBC [8] or The Times [9]. However, there is no mention of an already existing discussion surrounding Sulfoxaflor. Pesticide Action Network Europe (PAN Europe), Unione Nazionale Associazioni Apicoltori Italiani (UNAAPI) and BeeLife had already denounced that Sulfoxaflor was indeed not an alternative to neonicotinoids [10]. Based on scientific research, the categorisation of this insecticide would more accurately correspond to the 4th generation of neonicotinoids. Due to its systemic mode of action which acts on the central nervous system and its close relation to neonicotinoid Imidacloprid, researchers had already suggested for sulfoxaflor to be considered a neonicotinoid [11].

Sulfoxaflor was introduced into the market in China [12] and the USA [13] in 2013. In Europe, it was reviewed by the EFSA in 2014 and approved in 2015. The approval led Pan Europe, UNAAPI and BeeLife to challenge the decision by the European Commission, since it was considered absurd, mainly taking into account that Sulfoxaflor acts on bees’ in a similar way as insecticides from neonicotinoids family, which had been partially banned in Europe two years before. In the United States where sulfoxaflor-based pesticides have been marketed since 2013, the beekeeping sector was already pushing the Environmental Protection Agency (EPA) to withdraw it from the market [14].

In October 2015, Bee Life, PAN Europe and UNAAPI challenged the authorisation of Sulfoxaflor at the EU Court of Justice. The case was based on what was then called "the incomprehensible and unacceptable decision of the European institutions not to comply with regulatory requirements and scientific advances occurred in recent years on the protection of bees". However, the court rejected the appeal. One of the principal arguments was that the approval of Sulfoxaflor by Commission Regulation needed to be implemented by Member States through the granting of authorisations before it could be put on the market or used in their territories. Notwithstanding, the appeal argued that the approval of Sulfoxaflor had an immediate effect, as Member States can decide to 'automatically' authorise the substance in the formulation assessed for the approval. Besides, a lack of margin of appreciation in every authorisation procedure raises the question if Sulfoxaflor can, under certain conditions or in specific formulations, be applied safely, as the Commission decided that there is at least one safe application of sulfoxaflor possible. Through these arguments, the appeal argued that the regulation could have a direct impact, which was not necessarily preceded by the implementation [15].

Three years later, Sulfoxaflor is in the spotlight. There is an opportunity to review the research on this insecticide, cautiously avoiding falling into a 20+ year discussion during which dangerous products continue to harm bees, their pollination services and their role in ecosystems (as already occurred with neonicotinoids). New products, even those presented as alternatives may still have concealed characteristics. Dow AgroSciences has avoided the neonicotinoid label for their product, and some years later, it seems to be essential to remind policymakers, farmers, beekeepers and all stakeholders, that the distance between Sulfoxaflor and neonicotinoids (regarding classification and risk to bees) is not as extensive as it is portrayed to be.

[12] Shao X, Swenson TL, Casida JE Cycloxaprid insecticide: nico- tinic acetylcholine receptor binding site and metabolism. J Agric Food Chem, 2013.

[13] DoW Agro Sciences, DoW AgroSciences receives US EPA Registration for Sulfoxaflor, 2013

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