Ben Eastick Written by Ben Eastick

Striking a fair balance: insecticides and sugar beet growing

With increasing pressure from the EU on growers, a solution needs to be found that controls insects but promotes high yields.

Why do sugar beet growers need insecticides?

An insecticide is a substance designed to kill insects, in either adult, larvae or egg form. It is vital to modern day agriculture and is seen as being one of the key drivers behind the enormous boost in agricultural production in the 20th century. This does not mean their use doesn’t present issues, with many having the potential to significantly alter ecosystems and disrupt food chains.

As sugar beet is susceptible to the highly damaging Virus Yellows that are transmitted by aphids, insecticides are essential to ensuring yields remain as high as possible. There are three main yellowing viruses: beet yellowing virus (BYV), beet mild yellowing virus (BMYV) and beet chlorosis (BChV). These can be only be distinguished from one and other through laboratory testing, although each results in varying amount of damage to sugar beet yields.

Such is the potency of all yellowing viruses, the outbreaks of the early 1970s caused many growers to have to give up on beet altogether. Entire fields can quickly be engulfed by the disease, resulting in yield losses of up to 50%. What’s more, there are currently no resistant varieties of sugar beet available to growers across the globe.

Carried by aphids, Virus Yellows have the potential to quickly devastate livelihoods.

What insecticides protect sugar beet crops?

Sugar beet is protected from Virus Yellows by using neonicotinoids as a seed treatment control measure. Developed to mimic the chemical properties of nicotine, the members of this insecticide family used to treat sugar beet seeds include thiamethoxam, clothianidin and imidacloprid. These are favoured by farmers due to the speed and ease with which they prevent the development of several potentially devastating diseases.

But, as is the case with any insecticide, neonicotinoids do not come without their ecological challenges. When first introduced, they were initially believed to have relatively low toxicity to any insects other than the ones they are designed to kill. This assumption was proved to be wrong after a dramatic loss of beehive numbers in 2006 proved that neonicotinoids were in fact lethal to bumble bees.

As well as killing bees, these crucial pesticides can also attribute to colony collapse disorder (CCD), whereby the majority of worker bees vacate a hive and leave just a handful of nurse bees and a queen behind. In turn, the hive can no longer effectively function, and, as the name suggests, collapses and eventually ceases to exist. Although long anecdotally believed to be caused by neonicotinoids, the link was made concrete in an essay published in the peer-review journal Current Opinion in Environmental Sustainability. Due to evidence of this nature and in a bid to protect bee populations, the European Union (EU) restricted the uses of neonicotinoids in 2013 before completely banning their use on any outdoor crop in 2018.

What has been the impact of the EU’s decision to ban neonicotinoids?

As with anything that pits environmental and ecological considerations against the productivity and profits of farmers, the ban has been highly divisive. Environmentalists labelled the initial ban as a “significant victory for common sense and our beleaguered bee populations” that was backed up by “crystal clear” public support. Conversely, the UK government, who along with 8 other EU member states voted against the ban, claimed “we did not support the proposal for a ban because our scientific evidence doesn’t support it.”

Unsurprisingly, the reaction from sugar beet growers to the wholesale ban has been overwhelmingly negative, with some even going as far as to suggest it could disrupt yields for the next decade. Although planting fell in Germany for the current season, the UK yield is expected to be at least as high as last year, with this being all the more pleasing giving that the 2019 season is the first to bear the brunt of a total neonicotinoids ban.

The fact that only one season has passed post-ban also shows that more time is needed to draw useful conclusions from its impact. With virus-resistant sugar beet crops at least several years way from being commercially viable, the only interim solution seems to be on that satisfies growers without leading to destruction of bee populations. It remains to be seen what this is, with many farmers still seeing the EU’s decision as short-sighted and not based on concrete scientific evidence.