Putting the Wild in Flowers and Bees (Ep. 12)

Wildflower strips are often used in the UK and other countries as part of agri-environment schemes to increase plant diversity on farmland. These strips are meant to attract a broader range and greater number of bumblebees, solitary bees, and other pollinators. But do they? Today we’re talking with Dr. Rachel Nichols about how we can make these wildflower strips better for bees and farmers alike. 

Dr. Rachel Nichols is a Research Scientist in Farmland Ecology at the Game and Wildlife Conservation Trust. She has a PhD in wild bee ecology from the University of Sussex in the United Kingdom. Read the full study we discussed in this episode here. Follow Rachel on Twitter for all her latest bee fun.

It’s very simple to plant wildflowers in your garden. Watch this easy video from WWF UK to learn how.

Did you know?

Pollinator professionals often advocate planting wildflowers for bees in home yards and gardens. Yet, doesn’t that go against the definition of something being “wild?” Often the terms wildflowers and native flowers/species are used interchangeably. Typically, wildflowers are native plants and grow in woods, meadows, wetlands – anywhere they adapted to grow.

Transcript

[00:00:00] Land use change is often cited as one of the drivers of pollinator loss. This happens in both urban and rural settings, with a variety of interventions being tested to see if they can help bees stay resilient in the face of habitat loss. We recently talked about creating pollinator habitats and that just the fact of having them improved bee abundance and diversity.

However, the researchers in that study also found that the quality of the habitat plays an important role. And improving quality is what we’re going to discuss today with our guest, Dr. Rachel Nichols. Her recent study looks specifically at the seed mixtures used on farmland with an eye to providing forage for pollinators.

Thank you, Rachel, for joining us. Can you begin with a brief explanation of what wildflower strips are and [00:01:00] why they are implemented? Um, yes, typically wildflower strips are implemented as agri environment schemes in the UK on farmland to boost plant diversity. And they… They therefore attract or provide resources for more insects and, or a greater diversity of insects.

What type of wildflower mixes are typically used in these strips? Or in the UK, there have typically been something called the pollen and nectar mix, which has been used for many years. And it’s very, uh, legume or pea based. So it contains things such as red clover, outside clover, birdsbit trefoil, as well as some perennials.

Um, when it was initially instigated as a mix within the agri environment schemes, it was quite a low diversity mix. Now it is a more high diversity mix, but that was the initial one that, um, was used in the UK. And there has also been an instruction of a, oh, sorry, there has now been a more diverse wildflower mix introduced, [00:02:00] which has just got a wider range of species that covers a wider range of flower families.

And that’s probably 10 to 15 species that’s now included in that mix. Now, for this study, you created two novel wildflower mixes. Can you tell me what was different about those? Yep. So I created two mixes. These, these were based firstly on the literature and then on primary research. So the literature based one, I trawled the…

all of the literature that was out there, um, everything that was published, everything that was gray literature, everything that was in books. Um, basically looking for species that were shown to have a high diversity, specifically of solitary bees. Because there was so much data or information on honeybees and bumblebees, there was less species level data on solitary bees.

It was quite difficult to find those sorts of figures like it, it would just say, and wild bees. They were just [00:03:00] categorized or grouped together, there was no species level, so I couldn’t go through and go, this one attracts a high diversity, because I can see that, you know, X, Y, Z, different species go to this bee.

I could just see that a high abundance of solitary bees would go into this bee. So, the initial literature based mix was highly based on high abundances of solitary bees that use those species. And so because I couldn’t get that species level data, I then did a primary research based mix, which is where I went to a wildflower farm.

So obviously all these seed companies that produce all these seed mixes grow their flowers on land or on farms as big wildflower crops. So, um, I was able to visit one of these farms, over the course of the spring and summer season through one year and survey these specific crops that were flowering at different times of the year and ID the species of wild bee that were using them so I could find out which [00:04:00] flowers to then include in a seed mix that would get the highest diversity of wild bees.

So those were my two mixes, a literature based mix and a wild bee primary research mix. So you studied your two mixes against the two commonly used mixes, and then you had a follow plot as a control. What did you find? So I found that my primary research based mix, the wild bee mix, attracted the highest abundance of bumblebees and solitary bees and all insects,

and also the highest diversity of solitary bees and bumblebees. So the, the primary research mix attracted a higher diversity of solitary bees and bumblebees than the fallow plots or the typical pollen and nectar mix. Did anything surprise you about the results? Um, yeah, we were surprised, or I was surprised to see that the pollen and nectar mix did as poorly as the fallow plots statistically, in many cases.

So you’d hope that [00:05:00] by sowing a flower mix of some kind, especially one that’s meant to target bumblebees particularly, would attract more insects or would attract more bumblebees, but when I did the statistical analysis and compared all the different mixes and plots… The fallow plots and the pollen and nectar mix statistically did no difference.

I think it was in terms of, uh, richness and abundance for solitary bees and bumblebees. Which is surprising. That is very surprising. Do you have any thoughts behind that? Um, I think that, I think that part of the problem is that the pollen and nectar mix was just too low diversity and too short lived. Because a lot of the species that are included in the pollen and nectar mixes are, or used to be, agricultural variety species,

and they flower later in the season than the wild types. And don’t… [00:06:00] Uh, last as many years as the wild types. So the agricultural varieties are cheaper to produce and include and establish well in seed mixes, but they don’t last as long. So as my experiment went over the three years, by the end year they just, there wasn’t enough, there wasn’t enough flowers left.

Sorry, there weren’t enough flowers left and there was just no comparison really to a fallow plot that’s allowed to naturally regenerate versus a plot that’s declined in floral abundance by that point. The wildflower mix that you created that had the best results, uh, were there plants or flowers included, uh, that would bloom throughout the season?

So you had some blooming in the spring and then throughout the summer? Okay, so yes, my primary research wild bee mix included species such as dandelion which flower early in the year, so that’s going to attract a lot of emerging queens. Um, and early, uh, sorry, solitary bees with early flight seasons. And then I also [00:07:00] included a species called heterogeranium, which flowers for quite a few months in the summer and attracted a really high diversity of solitary bees throughout the whole summer season.

And then I also included species such as, um, kidney vetch, which attracts a lot of bumblebees, but also over quite a long period of the summer because it flowers for quite a few months. So, I tried to capture as much of the season as possible with my mix. So, how can we use this information to create better pollinator habits around agricultural land?

I think the key message is that the seed mixes need updating because we’re, we use quite a, um, a specific list, I guess, that the, the government body in the UK provides as suggestions to farmers of species they could include and the seed companies produce their seed mixes based on those suggestions. So if a farmer was to turn around and say I want a bespoke mix based on these suggestions in [00:08:00] this research it’s going to cost them a lot more money.

So what we need to do is encourage the farmers and the seed companies to update their mix knowledge and the different things that they put in there. So what we want to encourage is a lower percentage of grasses, a higher percentage of wildflowers, a change up in some of the species, fewer agricultural varieties, more wild type varieties, and a better mix of some of the key species highlighted in my paper and other recent research that shows that you don’t need the biggest diversity ever, you just need some key species in there that are going to go throughout the whole summer.

Or going to cover all the species throughout the whole spring and summer season. And are going to be able to target a wider diversity of bees over that time. Do you have a favorite bee? Yes. The, it’s called Andrena cineraria. It’s the ashy mining bee. So it’s one of the solitary bees, one of the Andrena species.

It’s a ground nesting bee. [00:09:00] And it’s all black. But it has a sort of a ashy, gray, white, thorax, like fluffy coat. It looks like it’s wearing a little fluffy shawl. I just think it’s kind of, kind of cool. And it’s, it’s one of the solitary bees, it’s quite big. It’s about the same size as a honey bee. So it’s easy to spot.

It’s not like one of the tiny mining bees. So you can spot it straight away. And they’ve got quite noticeable nests. They go on quite hard, hard sloped ground where it’s quite bare. So you can see them and you can see them going in and out. So they’re quite interesting to spot and to watch. How can home gardeners use this information?

on wildflowers in their own spaces. So we need to encourage landowners, gardeners, homeowners to, you know, spice it up a little bit in their gardens, not just to go for the pretty, like, ornamental roses, but to go for the wild versions when they can, and to mix it up diversity wise in their garden, um, make sure they’re allowing space for some weeds occasionally without [00:10:00] it destroying their, their beautiful edges or their lawns.

And we also encourage something in the UK called No Mow May. So it’s where you don’t mow for the month of May. And it’s just, uh, encourages as much, uh, floral abundance to come up as possible in that time so that you can really, um, provide a lot of forage for those early flying species and to help bee nests establish and things like that throughout May.

Why are flower strips so important? So they provide a brilliant resource for insects on farmland, so they, uh, so this is great from both a biodiversity standpoint in terms of intrinsic value of the species of both the flowers but also the insects that we can attract with them, but then they also provide forage which allows insects to survive throughout the year on farmland, but they also can then provide, um, services to us as humans.

So we get crop pollination from them, wildflower [00:11:00] pollination, integrated pest management, where they can help attack the crop pests that we get. Greatest threats or what we can do to support them in these times of climate change and land use change and pesticides and all the other stressors that they meet in their tiny little daily lives.

So bumblebees and honeybees typically have larger colonies. So there’s a bit more leeway in their ability to forage and provide extra food to keep the colony going through hardship periods, you know, when there’s not as much floral resources available, or there’s been particularly bad weather, they can redirect their foraging efforts to ensure that they’re getting enough nectar and pollen, or they can control the egg laying behavior within the nest, so they can control the colony’s overall [00:12:00] activity and ensure that the colony and the queens survive to the next generation. Whereas solitary bees, except for the eusocial species, which live in sort of colonies, but not quite, that have a founder’s queen, typically, you’ve got one foraging female.

So if anything happens to that female or her nest, that’s that entire generation lost, as it were. So, I think they’re particularly vulnerable to climate change, to bad weather events, to, um, asynchrony in floral emergence and bee emergence, because they will emerge at a certain time, often when there’s enough warm weather in the day, or sunlight or sunrise is from a certain time, the bees are going to start emerging, but if we’re still getting frosts at night, we’re not going to be getting the flowers for them to forage from, so there’s going to be an asynchrony event.

Um, and we’ve already seen a change in springtime is shifting earlier. [00:13:00] There’s not quite, we’re going to start seeing mismatches, so climate change can affect them that way quite easily. The, um, she needs to collect the preferred pollen species for the, ideal development of her egg cells, depending on the species.

So each species is slightly different. So if we’re getting asynchrony with her preferred species, she’s going to be providing pollen that may not have the ideal nutrient content for her larvae and eggs, like, sorry, her larvae stage of her eggs, or so of her offspring. So I think that’s maybe one of the major concerns is that it’s those small details of not providing the correct nutrients, therefore, The offspring aren’t going to grow as large, therefore there’s less likely survival of overwinter, overwintering, and then when they emerge the next year, fewer numbers are going to emerge the next year.

So simple things like that, it sort of [00:14:00] snowballs into all of a sudden, one year, you’ve got loads of bees, and then the next year, you’ve got no bees. And that’s fine in… Like simple sort of peaks and troughs of populations, but when you’ve got an accumulation of weather events such as things like, like climate change are causing, eventually it will sort of have a knock on effect year on year on year and that’s when we’re seeing more declines.

So that’s why I think solitary bees are particularly important to research and to understand and to help in our research because we need to ensure that, uh, we are able to counteract these effects. Interventions like wildflower strips can have a large benefit on solitary bees, as Rachel’s research showed.

Like all diets, though, they need to have variety and be rich in nutrients to fully give bees what they need throughout their lifespans. If you’re able to, why not try some wildflower species in your own garden? The colorful additions may bring a buzzy new dimension to your yard. [00:15:00] Thanks again to Dr.

Rachel Nichols for sharing her research, and thank you for listening. Please follow the show and tell a friend. It does a lot to promote the show and the bees. Looking forward to having you back here in August. Until then, keep buzzing.