Even right now, we still need natural history stories

I don’t have time to write a blog post right now. I’ve got data analysis that’s way overdue, papers that should have been submitted a year ago, and kids whose social-emotional-educational needs are barely met these days. And yet, against all odds, I had a paper published a few weeks back that I just love, so against all odds, I’m taking the time to celebrate it.

The paper is not even a whole paper – it’s a note, Herbivory on non-native parrotfeather (Myriophyllum aquaticum) by the beetle Galerucella nymphaea”, published in Proceedings of the Entomological Society of Washington. In it, I and my co-authors Kim Patten and Chase Metzger describe our collective observations (over more than a decade) of extensive herbivory by a native beetle on a problematic invasive aquatic plant. It’s a science story, but it’s also a story about being open to the unexpected, about adapting while remaining true to essentials, and about persistence. In fact, maybe I am forcing myself to celebrate because it feels a lot like what I and a lot of folks I know are doing to get through homeschooling, working from home, and trying to “science” during a pandemic.

My part started in 2014, when – while doing fish sampling along the Chehalis River in a little wetland that we had nicknamed “Despair” – I noticed larvae on some of the parrotfeather plants. On a whim I took some photos to send round and ask if anyone knew what the insects were. I sent the pictures to a few people, and no one recognized the insect, or had seen the interaction before.

Fig1_MAQ_GNY

Herbivory on non-native parrotfeather (Myriophyllum aquaticum) by larvae of G. nymphaea

But maybe six months later I found a very brief reference in a project report by Kim Patten at WSU, where nearly ten years earlier he had noticed extensive grazing by Galerucella nymphaeae on parrotfeather in drainage ditches in Longview, WA. In fact, he noted that the herbivory was so extensive that it may have interfered with uptake of the herbicides being tested. Figuring the mystery was solved, I set my photos aside.

A year later (in 2015), I visited Despair again, as part of a different project surveying and experimentally treating parrotfeather sites along the Chehalis River. I was shocked, because the entire (large) extent of parrotfeather canopy had been defoliated to the point that there would have been no point in treating it with herbicide. I mapped the canopy cover along with the other treatment and control sites, though, interested in what it would look like the following year.

The following year, there was still plenty of parrotfeather there. But the thing was, it was a hot dry summer, and only four out of 18 sites had less parrotfeather than in 2015, regardless of whether they were treated or

SuppFig_herbicidecontrast

Fig. 1. Change in parrotfeather canopy area from 2015 to 2016 in herbicide-treated (circles), control (squares), and the site with extensive herbivory.

control sites. Not only was Despair one of the four, but when adjusted for total canopy area, the reduction in canopy cover was very dramatic (Figure 1). In other words, a site with that much parrotfeather canopy in 2015 should have increased, and by quite a bit. This suggested that extensive herbivory by G. nymphaea might be at least – and potentially more – effective than herbicide treatment.

In 2016, Despair was the only site with herbivory. However, when I got back on the river in 2018, I noticed widespread herbivory in new locations where I had never seen it before. So, I rounded up some friends with boats, and spent 4th of July holiday floating portions of the river and checking all 22 original sites. I found beetle larvae grazing the parrotfeather in almost half (48%) of the sites in 2018, and 38% of them in 2019 (Figure 2).

Fig2

Fig. 2. Proportion of sites with herbivory and the extent of canopy impacted in each year. Based on survey of 22 original sites with parrotfeather.

Somewhere along the way, I convinced Kim that there was a story here, and if we combined his 10+ year old observations in Longview with mine from the Chehalis, it was a story that should be told. The first three journals disagreed (in part because we included other data that was too unrelated), but we kept revising, kept surveying, and found a home for the essential story of how a native beetle seems to have adopted a novel non-native plant as a routine food source. Whether adaptation is occurring, and G. nymphaea is broadening its niche, or if it’s just temporarily taking advantage of a locally plentiful food supply, are questions that will have to be answered by others in the future. But at least the story is out there now, ready to be grabbed hold of.

Right now, when everything is so difficult and awful, it’s hard to feel that our natural history and ecology stories matter. But they do matter. They are not only stories about bugs, plants, water, and weather, but about patience, collaboration, creativity and persistence. About the unexpected, curious world that’s out there waiting to be stumbled upon and noticed. And that’s something we can all hold to for the future.

About Lauren Kuehne

Fish, freshwater, invasive critters
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