These articles covered recent science papers that have caused a lot of concern, and generated a lot of attention. In the ENT 518 class that I am teaching this term (Current Topics in Entomology), our class spent time dissecting and discussing the science papers, as well as popular press coverage of each study.
The first paper, published in 2017 by Hallman and colleagues, documented a 76% decline in insect biomass over a time period spanning nearly three decades. In the peak summer season, the decline was even larger (82%). These researchers had been sampling protected areas in Germany using Malaise traps. This group is working to identify the insects that they collect ~ but, because it takes so much time and specialized expertise to identify most insects to species ~ they also took data on the collective weight of the insects that they collected. This is how they were able to show a 76% decline in insect biomass, between 1989 and 2016.
What caused this massive decline in insect biomass? To address this question, They constructed a series of models to try and identify what factors might explain this precipitous drop in insect biomass (which is being used a proxy for insect abundance). They did not find evidence (from their mathematical models) that climate factors (e.g. temperature, precipitation, wind speed), habitat factors (e.g. site conditions, plant species), or habitat factors (e.g. amount of forest, grassland, water) were responsible for insect declines. Because they did not find evidence that climate change, landscape conversions, or habitat changes reduced insect biomass, they concluded that factors which they did not measure were responsible for insect declines. Specifically, they hypothesize that agricultural intensification (pesticide use, year round tillage, increased use of fertilizers) was a plausible cause.
Students taking the ENT 518 class were mostly convinced that the researchers had documented a large and significant decrease in insect biomass over the time period of the study. Students agreed that the loss of biomass reflects a loss in insect abundance, and probably reflects a loss of insect diversity. Students were more reserved in their assessment of the authors’ suggestion that agricultural intensification was the cause of the decline. Although they agreed that it is a plausible explanation, they wanted to see data to address this hypothesis, rather than having the authors arrive at this conclusion because they eliminated other potential causes of insect decline (e.g. climate change, landscape conversion, habitat change).
The second paper, published in 2019 by Sanchez-Bayo and Wyckhuys, was a review of other papers that studied insect declines. The authors searched science databases for the words ‘insect’ AND ‘decline’ AND ‘survey’, and then reviewed the hundreds of papers (653!) that they found to limit their survey to 73 long-term studies that took place for 10 years of more. The authors then summarize the details of each study, according to major insect groups (e.g. butterflies, bees, beetles, flies). Ultimately, they report that 41% of all insects are in decline, and that across all insect species, the annual rate of decline is 1% per year, and the annual rate of insect extinction is 1% per year. Like the Hallman et al. paper, Sanchez-Bayo and Wyckhuys suggest that agriculture is to blame:
‘Overall, the systemic, widespread and often superfluous use of pesticides in agricultural and pasture land over the past 60 years has negatively impacted most organisms, from insects to birds to bats . . ‘.
The students in ENT 518 honed in on the fact that the authors searched for the words ‘insect’ AND ‘decline’. Accordingly, there was a level of bias in their search procedures. Students seemed convinced that many insect groups are in decline, but were less willing to agree that the overall level of decline, rate of decline, and rate of extinction reported by the authors were accurate estimates. In addition, although students agree that pesticide use is likely to blame for insect declines, they would have been more convinced, if there were better data tying the two together.
Students then discussed how the science papers were translated into a narrative for the NY Times and Atlantic articles. We talked about the elements of a story, and how as scientists, we don’t worry about setting the scene, developing characters, or of conflict in a plot. But, many of us are also science communicators via our work in Extension or through other outreach efforts. If we can paint a picture that people can relate to ~ if we can get them to notice and to share their experience with noticing fewer insects in their yard or their town ~ will they care more about insect conservation?
One of the major reasons that we do the work that we do in the Garden Ecology Lab is because we believe that how we manage our gardens can truly make a difference to insect conservation. If we can take better notice of those ‘little things that run the world’ and share these experiences with our friends and family . . . will that make a difference? I believe that it will. In fact, it is the reason that I come to work, each and every day, excited to learn more about how we can make this world a better place through gardening.
If you love bees, and you have not yet subscribed to PolliNation, you’re missing out! OSU Professor and PolliNation podcast host, Andony Melathopolous, does a wonderful job assembling a diverse array of guests to talk all things pollinator.
Aaron talks about the 100+ study plots that he manages (two of which you can see, below), as well as which plants were most attractive to bees (such as the California poppy, on the left) versus those that were more attractive to gardeners (such as the Oregon iris, on the right).
In other news, our lab group has been very busy. All of the 2017 and 2018 bees from our garden pollinator study have been identified to species (unless they are truly recalcitrant to being ID’d to the level of species). Gabe has been working with Lincoln Best to identify the 2018 bees. The 2017 were verified by Sara Kornbluth, and provided a great reference collection against which we could compare the 2018 bees. Gabe has been a short-time member of our lab group, but his expertise has been a huge benefit to our program. He leaves us at the end of April to start field work in the College of Forestry. After that, he heads to UC Davis to do his Ph.D.
After two years of amazing assistance in the lab and in the field, Isabella has started an independent research project on campus. She has planted some of Aaron’s study plants in gardens on campus, and is looking to see if bee visitation and bee communities markedly change, when you take them out of single-species plantings (like Aaron is studying) and put them into a garden setting.
Mykl is working to write up his urban soils data for publication. We are also hoping to do a side publication, comparing the soil types that we’re finding in home gardens, and seeing how they align with the types of soils that nesting bees prefer.
Lauren is writing up her capstone paper, and is preparing to defend this term. She surveyed gardeners to try to understand how well they can identify bees from other insects, and how well they knew bee-friendly plants from those that offered few or no nectar/pollen resources to bees.
Signe is taking the data that we are collecting, and working our findings into the online Master Gardener course. The best part of our work is being able to see gardeners put some of our research-based recommendations into action. Signe plays a huge role in translating our work for the general public.
Angelee is a relatively new member of the lab. She comes to us from the OSU STEM Leaders program. She’s learning lab protocols and lending a hand on just about every project. She has been a joy to work with.
Lucas has moved on from the lab, but still helps us with remote data-basing work, on occasion. He was a joy to work with, and I feel lucky that he stuck with us for a few years.
This entry is from Angelee Calder, and undergraduate Agricultural Science student at Oregon State University. It highlights a bumblebee that can be found in Oregon gardens, but that is currently listed as ‘Vulnerable’ to endangered species status, due to documented population declines (Hatfield et al. 2015).
When we think of bees, we usually conjure up the image of a cute fuzzy black and yellow puff of an insect. Bombus fervidus, which is also known as the Golden Northern Bumble Bee,looks just like that cute bee stereotype. This bumble bee has a black face, yellow body, and single black band across its body near its wings (Discover Life 2019). Although Bombus ferviduscan be found across most of the whole United States, studies have shown that their population numbers are declining (Colla and Packer 2008). This bee is attracted to clover, which is one reason to tolerate (or even embrace) clovers in residential lawns.
We spent 120 hours hand collecting bees from 24 Portland area gardens in 2017 and 2018. In addition, across these two years we set out water pan traps to collect bees for an additional 3,450 hours of passive collection. In all this time, we only collected two Bombus fervidus. Both were collected from the same yard in August 2018. This yard is our largest garden, and it sits adjacent to Forest Park. It could be that this species, known to be in decline, does best with larger patches of habitat, that are close to a natural area.
The Northern Golden Bumble Bee is in the running for cutest bee, so make sure to take a look while he is out foraging. The peak viewing times to catch a glimpse of these cuties May to October (BugGuide.Net 2019).
Colla and Packer. 2008. Evidence for decline in eastern North American bumblebees (Hymenoptera: Apidae), with a special focus on Bombus affinis Cresson. Biodiversity and Conservation 17: 1379. https://doi.org/10.1007/s10531-008-9340-5.
Isabella Messer has been a member of the Garden Ecology Lab for more than two years, where she primarily assists with the garden pollinators study, but will is also developing her own research project. Her independent research project will look at bee visitation to some of the plants we are studying in controlled research trials, when these same plants are in a mixed garden setting. Controlled research trials are important, because they let us document the attractiveness of plants to bees, in a setting where study plants are not competing with other plants for pollinators. Controlled research trials are also valuable, because they let researchers have better control over environmental conditions, such as irrigation. Isabella is going to see whether and how bee visits on plants in a garden context is different than what Aaron is documenting in his controlled research trials. This will be one of the first, if not the first time, that we will have direct and contemporaneous measures of bee visits on focal plants in each situation: in a research field, and in a garden.
In addition to her work in the lab, Isabella is also a member of the ‘Research Retinue’: a group of Oregon State University undergraduates, who review and discuss papers on the PolliNation Podcast.
In this episode, the retinue discusses two papers that look at the impact of a common herbicide (glyphosate) on bees, via indirect impacts of glyphosate on the microbiome (bacterial community) that can be found in honey bee guts.
Aaron’s webinar on his Ph.D. research has been posted on YouTube.
He highlights some really interesting results from his 2017 and 2018 field seasons, including recommendations for what to plant, if you are interested in attracting native bees to your garden. I’ve asked him to write a blog post, summarizing the results to readers.
In case you missed the webinar on our garden bee research, I’ve embedded the video, below. The entire webinar is about an hour.
And, make sure to mark your calendars for Monday, October 22nd at 11am PST. Aaron Anderson will be presenting a FIRST LOOK webinaron his research on native plant-pollinator associations. Visit the hypertexted link, above, to register for this FREE webinar.
Aaron was sharing some of his latest data with me, just this past week. His data, collected at replicated field plots in Aurora, Oregon, echoes what we’ve seen in home garden sites around Oregon: for native bees, Douglas Aster was a top performer.
In 2017 and 2018, Aaron and Lucas took weekly counts of bees on their native plant plots. Aaron has summarized the data for 2017 (below) according to bee morpho-type. The morphotype categories are the same general categories that have been used by other researchers: bumblebee, honey bee, green bee, small bee, and big bee. These major bee categories are fairly easy to distinguish from one another in the field. Although, Aaron and I talked quite a bit about whether or not we should combine big bees and small bees into a new category: other bees. When does a small bee become a big bee? We had a general sense that a large Megachilerotundata would be a big bee, and a small Ceratinasp. would be a small bee. But, what about a smaller Megachile species? Is that big bee or a small bee? There is no clear answer.
Aaron and Lucas kept records of big bees vs small bees, as best as they could, but in the end, we might collapse all of that data into an ‘other bee’ category.Aaron recently surveyed gardeners, to ask their opinion on the aesthetics of his study plants. A quick look at the results suggests that gardeners and bees might be attracted to different flowering plants. While Gilia capitata was the most visited plant in Aaron’s study plots, it was ranked 6th most attractive (out of 27 plants) by gardeners. The story gets worse for Madia elegans (2nd with bees, 20th with gardeners), Aster subspicatus (3rd with bees, 14th with gardeners), and Solidago candensis (4th with bees, 23rd with gardeners).
Could it be that bees and gardeners are truly attracted to different types of flowering plants? Or could it be that if gardeners knew about the benefits of these Willamette Valley natives, that they might see a new kind of beauty in these plants?
We are so lucky that Lincoln Best has been in Oregon, supporting the work of the Oregon Bee Atlas. Linc was kind enough to take a look at Aaron’s bees, before going back to Canada. Aaron is currently taking a bit of time off, following his wedding this past weekend (Congratulations Aaron and Maura!). In everyone’s absence, I’m chomping at the bit to see what bees were identified from Aaron’s study of Willamette Valley native plants. So ~ for your reading pleasure, here is a preliminary list of bees collected from Aaron’s plant plots.
A few things to note about this list:
I give no mention of abundance of each bee species. Some specimens were caught many, many times off of a flowering plant species. Others were rare, and only caught once.
This list is not all-inclusive. It’s Labor Day. I’m working. I got excited about the bees, and wanted to share. But, I am not carefully going through every small label.
Some bees were only found on one or two flowering plant species ~ even though Aaron’s plots are all in the same 3 acre field (1X1m plots, with each plot separated from every other plot by 6 m).
Yellow-faced bumblebees were collected off of most plants ~ so I am not listing them, below. I also did not look at the honey-bee plant associations.
Linc dissected male genitalia (yes ~ that is how you need to ID some bees to species), and found FOUR Bombus calignosus (all associated with lavender)~ a vulnerable species on the IUCN Red List.
We also have Bombus fervidus, another species on the IUCN Red List (Vulnerable) on lavender, Salvia, and Gilia.
I’ll leave it to Aaron to make a rigorous accounting of bee-flower associations. But for now . . . on this holiday weekend, I was too excited to not take a peek and share initial findings with all o fyou.