mtvessel | Following the Science?

Oct 2020
A Buzz in the Meadow - Dave Goulson – Vintage, 2014
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I really enjoyed Goulson's previous book A Sting in the Tail, but with its focus on the highly charismatic bumblebee it was, entomologically speaking, an easy sell. This book expands the canvas to other members of the insect world, using as its focus Chez Nauche, a derelict French farm that Goulson has turned into a haven for wildlife (much to the bemusement of the locals). Can he make the sex lives of deathwatch beetles and the disgusting regurgitatory habits of bluebottles as compelling a read as the lives and times of more attractive insects? Yes he can, though it's only fair to warn you that the final few chapters may leave you feeling angry and depressed.

Goulson uses observational nature writing to hook the reader; he starts with a virtual tour around the grounds of Chez Nauche and each of the subsequent chapters is prefaced with an entry from the diary of his morning runs describing what he observed that day. His descriptive powers are astonishingly good, with a poetic quality you would not expect from an academic - I was reminded of some of the passages in Gerald Durrell's magnificent Corfu Trilogy. The bulk of the book consists of accounts of the scientific work that Goulson and others have done relating to some of the insects that can be found around Chez Nauche. This included his PhD on the wing spots of the common brown butterfly, which ended up calling into question the research of E.B. Ford, the highly respected founder of the discipline of ecological genetics and supervisor of Bernard Kettlewell, whose study of melanism in the peppered moth is a textbook exemplar of evolution in action. Ford was convinced that genetic changes in populations are entirely the result of evolution and spent much of his career arguing against genetic drift, the idea that in small populations, traits can be gained or lost due to random events rather than selection pressure. One of his lines of evidence was sharp changes in the frequency of spots on the wings of common brown butterflies in different geographical areas - such as a line roughly between Cornwall and Devon - which could not be readily explained by the genetic drift hypothesis. Goulson was unable to determine how having more or less spotty wings affected reproductive success (the obvious hypothesis - difference in predation frequency - didn't hold up when tested), but did find that slightly warming the pupae on one side caused the adults that emerged to have more spots on that side. In other words, the differences in spottiness that Ford saw were probably due to microclimate temperatures and not natural selection. As it happens, genetic drift has become an important talking point in ecology - it implies that small isolated havens for rare species are no use because the populations in them will become inbred and eventually die out - so although Goulson doesn't consider his research to have been a great success, a finding that undermines previous work against it is still important.

Later chapters focus in on the rich tapestry created by the web of relationships between plants and their insect pollinators, and humanity's apparent determination to rip it apart. A case in point is colony collapse disorder (CCD), the mysterious disappearance of honeybees from hives in Europe and the United States. With apologies to Goulson for plagiarising his book, I am going to tell this story in some detail because I think it's interesting. Buckle up.

CCD is a complex phenomenon that is probably triggered by a combination of factors including parasites such as the Varroa mite and the viruses it carries, malnutrition caused by the reduction in the diversity of flower species from which bees collect nectar, stress caused by regular transport of the hives to different crop areas (a practice particularly common in the US), and pesticides. Goulson has researched the latter, in particular the neonicotinamide group of insecticides, in some detail. Neonics, as they are known, are a boon to farmers because they are systemic - they disperse to all parts of the plant, which means that they can be applied as a seed dressing before the crop is sown, avoiding the need for expensive and wasteful dusting or spraying. However, it also means that they can be found in nectar or pollen, so they will be picked up by bees and other pollinators.

This was anticipated as a risk by the regulatory authorities, and agrochemical manufacturers duly provided safety assessments showing that it was not in fact a problem. In normal use, the concentrations of neonics in nectar and pollen were found to be so low that a honeybee would have to consume five times its own bodyweight to get an LD50 dose (the amount of a substance that causes 50% of a test population to die). This is a plausible amount for a bee to consume over its lifetime, which would perhaps be slightly shortened as a result, but overall didn't seem likely to cause any major declines in pollinator populations. On this basis, neonics were duly licensed for general use.

Following increasingly vociferous complaints from beekeepers and environmentalists about the use of neonics, Goulson looked at the evidence. Not from the safety assessments, because it turned out that there wasn't any, or at least none that met any criterion of scientific rigour. Only summary reports from the regulatory agencies were available and they did not give enough detail to assess what had been done. There were academic studies based on exposing bees to neonics in the lab, which confirmed they were not lethal at the concentrations typically found in nectar and pollen. They did, however, note some changes in bee behaviour.

The problem with lab experiments is that they cannot replicate conditions in the wild, where bees often travel long distances from the nest. Goulson decided to set up a controlled experiment under more realistic conditions. This was tricky to do with no funding; Goulson had contacts who could provide nests of buff-tailed bumblebees, but finding an area of the country which was completely free of neonics for the controls turned out to be impossible. Instead, Goulson replicated the lab experiments for two weeks and then put the treated and control nests out in a relatively uncontaminated area of Scotland to see how they did. By the end of the season, in many respects, there was little effect - the treated nests were slightly lighter and had fewer adults and pupae, but not by much. The big difference, however, was in the number of queens produced - an average of 2 for the treated nests versus 13 for the controls. That would mean 85% fewer nests next year.

Goulson's paper was published alongside a study by scientists in Avignon that explained why this might be happening, albeit in a different species. By gluing tiny radio tags to foraging honeybees, they showed that after exposure to neonics, they often became lost when returning to the hive, particularly after travelling long distances in unfamiliar surroundings (Goulson compares it to trying to get home from the pub while drunk). This explains an odd feature of CCD which is that worker bees simply disappear from the hive. You don't see any corpses in and around the hive itself, as you might expect if it was a virus or other disease. Getting lost is a death sentence for a bee, and ultimately for the hive it came from.

So how did the the UK Government's Department for the Environment, Food and Rural Affairs (DEFRA) react to this evidence that sublethal levels of neonics could be contributing to CCD, as well as threatening wild bumblebee populations? By stating that the original safety assessments were fine and that nothing had changed. They did commission the Food and Environment Research Agency (FERA) to try to reproduce Goulson's experiment but without the initial lab exposure, and the results were published, un-peer-reviewed, on the internet. One can see why because they evidently ran into the same problem as Goulson did in trying to find an uncontaminated area large enough to accommodate the foraging ranges of bumblebees - the so-called control nests contained a selection of neonics. Despite this fairly obvious flaw, DEFRA claimed it as definitive evidence that there was no major effect of pesticides on bumblebees, on the basis that the study did not reproduce the decline in queen production that Goulson saw. In the EU, the UK consistently voted against the imposition of a ban on neonics until a change of heart in 2018. Since leaving, DEFRA has decided to allow the use of neonics to control viruses in sugar beet at the behest of the National Farmers Union and British Sugar, despite the increasing evidence of its disruptive effects on insect systems. Oh, and one other thing. There is evidence that neonics do not stick to the seeds as well as claimed - they can accumulate in soil and last for years. It could be DDT all over again.

It will come as no surprise to anyone who has watched the behaviour of our political masters over the past year that considerations other than following the science often seem to factor in government decision-making (despite their claims to the contrary). But DEFRA's perverse interpretations of scientific data in a way that consistently supports the views of farming and agrochemical lobbyists suggests that it cannot be trusted with the care of our nation's wildlife. Goulson's penultimate chapter, The inbred isles, describes what happens when biodiversity is not maintained - populations fragment into patchworks, become inbred, and eventually disappear. The final chapter describes the eco-collapse on Easter Island. Goulson's advice is to go outside, look and listen to the diversity around us. If we keep ignoring the warning signs, it won't be around for much longer.