Science - November 15, 2017

‘Alarming insect study unsound’

Roelof Kleis

The study in which researchers from Nijmegen conclude that three quarters of the German insects have disappeared is based on flimsy data. This was expressed by Wageningen entomologists.

Entomologist Kees Booij. © Guy Ackermans

In an article on Kennislink, the entomologists Kees Booij and Theodoor Heijerman mop the floor with the study that was published last month in PlosOne. The article was followed by many alarming articles in media in the Netherlands and across the borders. British newspaper The Guardian even wrote of an Armageddon that threatens all life on Earth. The Dutch House of Representatives wants to take measures to better protect insects. 

But Is that story true? Is there really just a quarter of the insects left compared to thirty years ago? Nonsense, say Booij and Heijerman on Kennislink. Both have fundamental points of criticism on the statistical substantiation of the article. ‘PlosOne should never have accepted this in the current form’, says Booij when asked. ‘I do not understand how it is possible. But unfortunately, these things do happen.’

The measurements were only done in a very small part of Germany, and many spots only saw a single or a few measurements over the 27-year period.
Kees Booij

The researchers of Radboud University used a long-term dataset of the Entomologischer Verein Krefeld (Entomological Association of Krefeld) which put insect traps in 63 German nature reserves. According to the researchers, the average daily catch dropped from 9 grams in 1989 to 2 grams in 2016. This is a decline of approximately three quarters. But according to the Wageningen researchers, this is an ungrounded jump to conclusions.

The primary point of criticism that Booij and Heijerman have is about the study itself. ‘This is not a monitoring study, as that would have required the yearly measuring of biomass in a large number of areas across Germany. The measurements were only done in a very small part of Germany, and many spots only saw a single or a few measurements over the 27-year period. This means the setup is fundamentally flawed and unfit to monitor a general trend.’

According to both entomologists, the dataset is unsuitable to perform trend analyses on. The data show significant fluctuations in biomass between the years. According to Booij, this is a known point in insects. The number of insects (biomass) can fluctuate up to a factor of ten in between weeks or years. The researchers are skating on thin ice by trying to deduce a trend from these data.

It is always an equilibrium between reliability and news value.
Kees Booij

The first year of measurements, 1989, was apparently a good year for insects in Germany. But according to Booij, that spike in the data is the results of merely six traps, which, to make matters more interesting still, were all located close to each other in the vicinity of Bonn. ‘Without that spike, not much remains of the diminishing trend.’ He does not understand why the reviewers did not see through that. Or perhaps he does: ‘It is always an equilibrium between reliability and news value.’

Upon the publication of the article by PlosOne, Booij immediately responded online. Neither the editorial office nor the authors of the article replied to his reaction. He is currently writing a scientifically substantiated response to the article. With his writing on Kennislink, he already throws the first cat among the pigeons.

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  • Jeff Harvey

    Thanks Kees for replying. This being the case, I have absolutely no qualms with the rather stark conclusions of De Kroon and team’s PLoS One study. The fact is that nature is in retreat. We are blindly approaching tipping points that if passed may have grave consequences for nature and humanity. We are living in a society where it is assumed that we can enjoy limitless consumption without any attendant costs. We as a civilization are making all of the same mistakes that previous civilizations made as chronicled by the works of historians like Redman and Tainter. The only difference this time is that we seem intent on taking much of the planet down with us. So what if there are some analytical discrepancies in the paper? The message of this and a wealth of other studies is unambiguously clear, as was laid out in the Bioscience article this week. Humans and nature are on a major collision course. This is where our efforts should be focused, not on ways of placating a society in denial. What I have learned as an ecologist working for almost 2 decades in the Netherlands is that there is a real reticence on the part of many scientists to lay out what is happening. Instead, the stark reality is candy-coated, which plays right into the hands of those anxious to retain the status quo.

    The point I am making is that you are wasting your time writing a rebuttal. Will it change anything? Of course not. Insects and other biodiversity are in deep trouble across the biosphere. The pages of the scientific journals are replete with evidence, so the PLoS One study only confirms what by now we know. The Living Planet Index makes stark reading. Long term data sets for birds, amphibians and many other ecological indicators are equally alarming. It’s time that scientists left their ivory towers and descended into the trenches to confront those who are intent on sending us into the abyss on the basis of short-term profit.

    • Rudy Jonker

      Hear hear

    • Marcel Volbeda

      I am not a person with a lot of knowledge about the workings of nature. I read this kind of information an decide if the increased costst form my familie (taxes or what ever) are worth it. Bulshit scientificstudies will not convince me. This is drama and about selling newespapars. The same forces that threaten nature because it has not cost entry in a companies balance sheet are using it to make money.
      I believe you need to convice the general populace for this potential problem if you want to have some results. You will not win me over for you're arguments this way. And if more people like me decide that they have no reliable sources to decide, they, like me, will do nothing.

      Sticking to facts alone is not going to work either because I have no base of reference for your facts. So a popular story that makes me understand and accept my own responsbility in this but is also confirmed factually correct will win me over.

  • kees van Heemert

    In 'de wereld draait door'werd door Bart Knols, slimme ? oud-wageninger, abusievelijk gemeld dat de bijen in China allemaal dood gingen (sic). Heb hem per mail gemeld dat dat onzin is. Als wetenschappers zo uit de losse pols de argeloze kijker op het verkeerde been zetten is er iets mis in de academische wereld.
    Ben blij met de respons van Wageningse entomologen.

    Onderstaand uitleg van de de kwestie China. Overigens de export van honing uit China groeit nog steeds. ra,ra.

    Kees van Heemert. Hoofdredacteur Bijenhouden

    De werkelijkheid over de Chinese bijen
    In de provincie China Sichuan zijn peren een cashcrop. Na de introductie van een nieuw perenras bleken de bloeitijden van deze peer en de bestuivers uiteen te lopen. Met honingbijen lukt het niet om de bestuiving te realiseren.
    Oplossing: handbestuiving.
    Daarna moest vanwege de perebladvlo veel gespoten worden. Resultaat: einde bijenhouderij in dat gebied. Niet in China! Als er biologische bestrijding wordt toegepast kan de veel goedkopere bestuiving door bijenvolken weer terugkomen.
    NB Het aantal bijenvolken , mondiaal, stijgt nog steeds.

  • Johannes Annema

    Het wordt tijd dat meer van dit soort "einde der tijden" uitkomst gedreven onderzoeken worden gesloopt door ware wetenschappers. Mensen met veel parate kennis die ongevoelig zijn voor sociale en budgettaire besmetting. Zij volgen puur en eerlijk de wetenschappelijke methode.
    Activistische wetenschap op bestelling (pseudo wetenschap) neemt nl hand over hand toe.

  • Gert van Maanen - Bionieuws

    Een beetje wederhoor kan soms geen kwaad. De Wageningse ecoloog David Kleijn noemde de studie in Bionieuws nog 'absoluut overtuigend en goed onderbouwd' ( ). Bovendien hadden de Nijmeegse auteurs je waarschijnlijk gemeld dat ze een speciale toelichting aan het artikel hebben toegevoegd over de (kritiek op de) opzet van de studie (

  • Kees Booij

    Exactly Jeff, that's why I have been working for the benefit of biodiversity and ecofriendly agroecosystems during mots of my life. That does not mean that critically following publications that raise a lot of questions is wasting my time. Also in te complicated field of ecology we need good and critical science. There is too much speculation around about natural phenomena so we have to discuss them.

  • Piet van Veghel

    We hebben helaas ook te maken met activistisch ingestelde wetenschappers en een organisatie zoals Greenpeace die wetenschappers betaald voor het gewenste resultaat dat deze moeten leveren. Het doel heiligt daarbij de middelen.

    • Patrick Jansen

      Dat is een ongefundeerde verdachtmaking. Deze onderzoekers - sterker: alle universitaire onderzoekers - zijn onafhankelijk. Hun werk wordt streng beoordeeld door collega's alvorens het wordt gepubliceerd.
      Veel wetenschappers die biodiversiteit onderzoeken - waaronder ikzelf - bezorgd over het uitblijven van een adequate reactie op de signalen die door wetenschappers worden afgegeven. En dus zeggen sommige wetenschappers het - al dan niet op persoonlijke titel - nog maar even wat duidelijker, zonder p-waarden en betrouwbaarheidsintervallen. Dat is toch wat we met zijn allen wilden? Wetenschappers moesten toch "uit de ivoren toren komen"?
      Mijn indruk is dat een steeds grotere groep mensen alleen nog open staat voor wetenschappelijke resultaten die het eigen geloof bevestigen, en de rest wordt verdacht gemaakt. Dat is een uiterst zorgwekkende ontwikkeling.
      Wat dat betreft was die ivoren toren een stuk beter.

  • Jeff Harvey

    While the data published in this study may be open to question, the fact that nature is in full scale retreat because of human activities is not, as the new article in Bioscience reassessing the state of the biosphere 25 years after the Rio Summit on Biodiversity shows. Polulations of pollinators are in serious trouble. Songbord populations - particularly of insectivorous passerines - are in freefall across temperate regions of the world. I am afraid the Kees Booij is wasting his time here. What frustrates me as an ecologist is that people like him are eager to downplay studies showing evidence for negative human effects on biodiversity, instead of doing what we should be doing now and raising the alarm. Using words like 'nonsense' to describe demographic trends that are repeated across a broad spectrum of taxa simply plays into the hands of those intent on destroying nature for profit. He can write his PLoS One rebuttal but I for one won't take it seriously. Trends in nature are clear by now, or ought to be.

  • Patrick Jansen

    Heeft de redactie eraan gedacht de Nijmeegse collega's te vragen om een reactie? Het is bepaald geen kinderachtig onderzoeksteam. Vol met slimme oud-Wageningers trouwens.

    • Kees Booij

      De reacties van de zeker deskundige nijmeegse groep zijn uitgebreid verwoord in de comments van het betreffende Plosone artikel. En een van de auteurs heeft al helder verwoord hoe hij tegen de discussie aankijkt.

      Reden genoeg voor mij om de kritiek verder te onderbouwen ...