The science about herbicides and monarch butterflies

Yesterday several of us blogged about population decline in the monarch butterfly (Danaus plexippus). I said that I hadn’t seen peer reviewed science about it. I still haven’t read the whole research paper, because I’m not logged into an academic library just now. But the abstract (summary) of the paper is open to anybody who can read. Here it is.

The authors say, ‘There has been a large decline in milkweed in agricultural fields in the Midwest over the last decade. This loss is coincident with the increased use of glyphosate herbicide in conjunction with increased planting of genetically modified (GM) glyphosate-tolerant corn (maize) and soybeans (soya).’

In other words, being good scientists, they make observations but they don’t assume that one thing causes another thing. It just looks quite likely, doesn’t it?

They conclude, ‘results strongly suggest that a loss of agricultural milkweeds is a major contributor to the decline in the monarch population.’

I’m grateful to GM Watch Reviews for drawing attention to this research.

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About argylesock

I wrote a PhD about veterinary parasitology so that's the starting point for this blog. But I'm now branching out into other areas of biology and into popular science writing. I'll write here about science that happens in landscapes, particularly farmland, and about science involving interspecific interactions. Datasets and statistics get my attention. Exactly where this blog will lead? That's a journey that I'm on and I hope you'll come with me.
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7 Responses to The science about herbicides and monarch butterflies

  1. Tony says:

    The comment you state above regarding their conclusion seems atypical of all unknown issues concerning modern age environmental practices. To me, the correlation exists and herbicides are part of the problem, duh! I’d ask, do we have it in us to change our ways? Often, in spite of solid scientific evidence, we choose to ignore it and progress as if the knowledge doesn’t exist. I tell you, this type of thing “gets my goat” Am I alone in these thoughts?

    • argylesock says:

      You’re not alone. People can indeed be wilfully blind.

      On the other hand, I feel glad that I’ve now seen the actual science. For all its faults, the academic peer review system works quite well. So does the cautious scientific method. To me, it felt like a breath of fresh air to read the cautious interpretation of results in the paper about the monarch butterfly. I’ve known scientists, who should know better, announce ‘proof’ of something that was far beyond what their data really showed.

      I’ve noticed that GM is a topic on which too many people leap to polarised opinions. Here on WP I’ve received insults, implied or explicit, when I haven’t leaped on whichever soap-box a person wants me to leap on. By the way, I don’t mean that you’re insulting me! – you’re not. Perhaps you and I differ in how much we want to judge against herbicides.

  2. Isaac Yuen says:

    I appreciate your diligence in analyzing this news. It’s really easy to get swept up by the implications of things that make sense on the surface, things we may want to believe to justify our thinking, but they may not be based on good data and sound research. Hopefully this study will lead to more studies that explore the relationship between GM crops and butterflies.

    • argylesock says:

      Thank you for saying this. Science isn’t always very clearly reported in the press. No doubt that’s because journalists’ task is to sell newspapers, television or whatever medium they use.

      Research scientists like to believe that we’re the objective ones. We should be so, and we’re done years of training to become so. But we’re only human. I’ve seen papers in the academic press that were clearly biased, as I mentioned upthread. It’s usual to announce who funded the research, which can be a sign of whether there’s bias, but the pressure to bias can be more subtle.

  3. Tony says:

    Some good points raised there Argylesock, on both of your replies. I am a relative newbie to the sciences, having lacked a general interest in it, all those years ago at school. So I apologise, if I don’t always get the gist of what is being put out there. Having said all of this, I am willing to listen and learn from others and my broad-brush opinion on the perceived correlation between a loss of Milkweed and fewer Monarch Butterflies seemed a no-brainer to me. Of course, this doesn’t mean this is the proper “cause and effect” scenario. Anyway, I’ll stop rambling and BTW, it would take much more to offend me than you might think. By simply mentioning our current governmental approach to caring for the natural world may start one off though.

    Best Wishes

    Tony

    • argylesock says:

      You’re exactly the kind of person I want to write for on this blog. I seek intelligent readers, some of whom are scientists or statisticians, but others of whom are not. ‘The intelligent general reader.’ So I’m glad that you’re here and discussing.

      I too am not entirely convinced about this Government’s approach to the natural world. You’ve probably noticed that here!

  4. Pingback: Anger grows against Obama after signing of Monsanto Protection Act‏ | Science on the Land

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