Helping YOUR Local Pollinators: The Problem with Wildflower Mixes, and How to Move Beyond Them

The last month of winter has arrived! Though spring will not truly be sprung for some time yet, many of us are looking forward to the warm sunlight, longer days—and to planting new spring gardens. When the weather starts to change, a young man’s fancy may turn to thoughts of fresh tomatoes ripening on the vine, fruit trees blooming anew each day, or flowerbeds filling with daffodils, geraniums and lilacs.

If you’re passionate about pollinator-friendly gardening and “saving the bees,” you may be planning to fill your garden with a wildflower mix that purports to do just that. Countless online seed and gardening stores sell packets advertised as “bee friendly,” “pollinator friendly” and so on, and frequently tack the word “native” onto these packets as well. Even Cheerios joined in back in 2017, shipping out millions of free seed packets in cereal boxes as part of its “Bring Back the Bees” campaign. However, while these mixes are bought (and usually sold) with good intentions, once planted, they do not always have the intended effect and can even do harm in some cases.

The U.S. is a very large country, encompassing several biomes from tundra to tropical rainforest and containing countless types of habitats and ecosystems. It is therefore very rare for any plant that is native to the U.S. to be native to ALL of it. In some cases a plant species that is native to one region of the U.S. acts as an noxious weed in another. Fortunately this is rare, but it is quite common for U.S. species planted outside of their native range to either fare poorly or simply contribute nothing to the local ecosystem. When seed companies stick the word “native” onto their products, it looks appealing, but that word means nothing without reference as to where the seeds are native.

Another essential fact to remember: most pollinator species have a limited geographical range, as well as a limited number of flower species from which they are specially adapted to feed. For example, hawk moths and certain long-tongued bumble bees drink the nectar of deep, trumpet-shaped flowers, and many non-honey bee species specialize in flowers that require “buzz-pollination”–forceful buzzing to knock the pollen out. With the exception of the incredibly non-picky (and non-native) honey bees and a few select bumble bee and butterfly species, pollinators thrive on flowers that are native to the same area as them—flowers to which they are most adapted.

So, when gardeners plant random mixtures of seeds that are not native to their state or region of residence, the flowers often provide little to no benefit to native pollinators in that region. Widespread ignorance of this fact can result in extensive, expensive planting campaigns that ultimately do little to help. This is precisely what happened with Cheerios’ efforts—once the seed campaign began, journalists and biologists were quick to point out that some of the flower species included were only native to certain parts of the U.S., and some not native to the U.S. at all. The campaign also focused mainly on honey bees at that time, which, though suffering decline, are non-native livestock animals—not to mention that lack of floral resources does not seem to be a major contributor to their decline. Attention to bumble bees, mason bees, sweat bees and other pollinating bee species is sorely lacking in many of these campaigns.

Ultimately, it is crucial to understand what flowers and landscapes are most beneficial to YOUR local native pollinators. But how can one know that? Here’s how you can find out:

      • Research which bumble bee, solitary bee, wasp and butterfly species are native to your region or state, and, if the information is available, which plant species they rely on most for nectar and pollen. If you have a large garden or farm, you might even be able to provide nesting habitat for bees and wasps! Look up the nesting preferences and habits of your local species, and see if you might be able to provide the type of landscape that could support them. (See “Resources” below for easy routes to start this process.)

      • Reach out to local experts! If your state has a university with an entomology department, see if anyone there works in pollinator science and reach out to them for advice. They may be able to tell you which native pollinators are most crucial for the local environment and/or most in need of help, and what you can do to provide resources for these species. Your city or state may also have a native plant society or pollinator initiative group that could provide similar information.

 

RESOURCES:

Saving Native Bumble Bees

In February 2020, a group of bumble bee biologist and conservation professionals gathered at the Minnesota Zoo, in Minneapolis, to work on conservation strategies related to the endangered Rusty Patched Bumble Bee (Bombus affinis).  The meeting, sponsored by the U.S. Fish and Wildlife Service, The Ohio State University, and the MN Zoo, was to discuss if ex situ conservation strategies could be employed to aid in population recovery in the future.  In November 2020 the final report from that meeting was released, facilitated by Kathy Traylor-Holzer of the IUCN SSC Conservation Planning Specialist Group.

Ex situ conservation involves the removal of individual organism from the wild, either for short term activities such as translocation and “rescue” activities, or for longer term programs like captive breeding.  To be sure, ex situ conservation strategies are not a panacea and should be approached carefully and thoughtfully.  At the Minnesota Zoo meeting we met for three days and through a structured workshop, we proposed and considered numerous ideas that had potential as ex situ conservation strategies.  Not all of the strategies we considered came out equal in the end and several are considered risky, or unlikely to create enough benefit toward species recovery to really implement.  Several other strategies have potential.

In the report we discuss some of the benefits of ex situ conservation beyond simply increasing population numbers and that is what I want to cover here.  The particular strategy that I want to explore here for bumble bees is captive rearing of colonies, which I have done a lot of over the years with both common and at-risk species.  While I have never raised colonies of RPBB (Elaine Evans is the only person I know of who has) I think this strategy can teach us a lot.  By rearing colonies in captivity, we have the potential to both increase a population for release, but we also can learn more about the species- its disease stress, nutritional needs, and mating biology, among other aspects of its biology.

Captive rearing colonies

To rear a colony in captivity you have to first catch a queen bumble bee in the wild and bring it into the lab.  Bumble bees need a steady diet of pollen and sugar solution and a warm, dark and quiet location to initiate nesting.  There are many techniques to induce a queen bumble bee to nest in captivity and if the conditions are right the queen will lay a clutch of eggs on a pollen lump and incubate them until they hatch into larvae.  At that point she will incubate them further and feed them more pollen for a couple weeks until they pupate.  For most species of bumble bees about 24 days after egg laying a worker bee will emerge as and adult.  In the lab humans have to provide a steady stream of food as the colony grows and after a few months new queens and males will be produced if the conditions remain good.  Once this happens queens and males are isolated with reproductive individuals from other colonies and allowed to mate before they can be released back into the wild. In some cases, you might choose to keep some of the mated queens in cold storage over the winter and have them establish colonies of their own the next year.

During the colony growth phase, you can learn a lot about the bees, such as how quickly the nest grows, how much they eat, and which diseases they are susceptible to.  There is, of course, a risk that the colonies will not initiate in captivity, or that reproductive output in the lab might be less than the wild, but even these failures can be instructive.  Understanding the conditions that lead to either success or failure of reproduction in the lab can inform management strategies in in field settings as well.

One of the most persistent questions around RPBB recovery is discovering exactly what led to the declines in the first place.  A widely circulated hypothesis is that a pathogen (Nosema bombi) from commercially managed bumble bees spilled over into the wild RPBB populations leading to declines across the range of the species.  While this may be the cause, it has never been definitively shown and the impacts of N. bombi on B. affinis has never been studies.  If ex situ populations can be established, we could investigate the relationship between this pathogen and RPBB either through observing opportunistic infections or through direct experimentation.  Further, impacts of other factors such as diet or climate conditions could be observed in the lab in controlled experiments and provide insights into the decline.

Of course, other strategies are considered in the report and have merit, including translocating queens or male bumble bees to augment wild populations with new genetic material or to reintroduce RPBB in areas where it has been extirpated.  As the report notes, there are many considerations including developing methods to ensure that bees taken into captivity are disease free and that release of captive bees does not move pathogens or parasites to new locations.

A rusty patched bumble bee. Photo credit Tamara Smith, USFWS

This report can help inform the decisions that federal and state agencies make to try to recover RPBB populations.  My hope is that the Strange Lab can continue to contribute to recovery efforts for this species in Ohio and beyond.

Making a mess for your bees

Hooray! Fall has finally arrived and 2020 is nearly over. This means cooler temperatures and shorter days. Here in Columbus, we lose over an hour of day length in September alone and while this change signals the return of pumpkin spice lattes and woolen socks, it’s also a notice to nature that winter is quickly approaching. Birds and monarch butterflies are making their way south, flowers drop their petals and go to seed, and the trees replace the green of summer with the brilliant palette of fall. (Read more about Ohio’s fall colors here!)

Whether you’re a seasoned gardener or it’s something you picked up during The Great Quarantine, you might be thinking about cleaning up your garden to prepare for winter. Traditionally, that means cutting back the dead vegetation and discarding litter, but if you are interested in insect conservation then consider this: leave it alone and save the clean-up for spring!

Insects have their own version of hibernation (called diapause) to avoid the colder months and they’ll need a safe space to hunker down. This is where your garden can play a key role as a sanctuary for insects. Native bees will hide out in the dead stems of your flowers and grasses, lady beetles in the leaf litter, and caterpillars in the rolled leaves and seed pods; some insects even lay their next generation of eggs on the surface of the soil. Regardless of their method, all of them rely on standing vegetation and fallen litter as a barrier from the freezing temperatures and dry winds. But if you’re more into birds, know that nearly two dozen species like the Northern Cardinal overwinter here in Columbus and they rely on this vital supply of “hibernating” insects to make it through the winter.

So, do the insects, birds, and yourself a favor and leave your garden to nature. Then kick back with your pumpkin spice latte and enjoy the fact that come spring, you will have more pollinators and beneficial insects than before!

For Further Reading:
Nature’s Best Hope: A New Approach to Conservation That Starts in Your Yard and Bringing Nature Home by Doug Tallamy
Grow Native: Bringing Natural Beauty to Your Garden by Lynn M. Steiner

Catching Bees in the Hocking Hills

On September 12, 2020, Dr Jamie Strange and the members of the Strange Lab visited Deep Woods Farm for a bumble bee catching venture. Situated near Logan, OH, an hour’s drive southeast of Columbus, this small farm in the Hocking Hills is surrounded by thick wildflower fields, forested hills, creeks, and even small hilltop caves.

With its floral diversity, abundance of good nesting habitat, and distance from urban areas, this land is prime territory for bumble bees. Unlike honey bees, bumble bees build their nests on or under the ground, often in abandoned rodent burrows, thick grass tufts, under compost piles, in fallen trees or in other sheltered areas. A wooded landscape thick with grasses, forbs, and shrubs provides these resources in abundance. The landscape also boasts many native wildflower species attractive to bumble bees, such as goldenrod and yellow crownbeard.

We caught dozens of bumble bees for our research training, although we only encountered one species (Bombus impatiens, the common eastern bumble bee), likely because they are active later into the year than most other species. In the process we also witnessed the massive diversity of other insects in the area, including many solitary bee species, which are also important pollinators.

Though the Midwestern states have seen much destruction of native habitats for the sake of agriculture, expanses of untamed, unmanicured, species-rich land can still be found, if one looks in the right places.

Liam Whiteman and Dr. Jamie Strange, netting bees on a wildflower-covered slope.

 

A common eastern bumble bee (Bombus impatiens) foraging on yellow crownbeard.

Queen Quest 2020

Bumble bees are both interesting creatures and yet really similar to many other insects that have evolved to live in the temperate and cold climates of the world.  One of the main problems they face is how to survive the winter.  Some insects like Monarch butterflies avoid winter altogether by migrating to Mexico each year, while other insects will find a warm spot in your house to survive, but like many insects, bumble bees spend their winter in the soil. They dig just deep enough to keep from freezing solid, spending the winter under protective layers of soil and snow. They can stay there for 8-9 months until the weather warms enough for them to dig out and begin feeding on pollen and nectar in the spring.

For bumble bees, only the queen bumble bee survives the winter and she does this alone, but we know very little about how a bumble bee chooses a site to spend the winter. To answer this question a bunch of scientists from across North America got together and started Queen Quest.  You can see the details here.

The Strange Lab has put together a Queen Quest team with six primary people.  I have been going out to Chadwick Arboretum weekly to look for fall flying queens with two undergraduates, Lizzy Sakulich and Dalen Moore, two graduate students, Liam Whiteman and Iliana Moore, and the lab post doc Dr. Kayla Perry.  We even have some of the arboretum staff keeping an eye out for queens searching for wintering sites so we can add that data to the Queen Quest database.

We hope to find some queens this fall and help answer some questions about the basic biology of bumble bees that has remained a mystery for many years. Want to help out?  Drop me a line. strange.54@osu.edu

-Jamie

Welcome Grad Students

The Strange Lab welcomes Iliana Moore and Liam Whiteman for Autumn 2020.  Iliana and Liam join the lab in the midst of the COVID-19 pandemic and have recently gotten to Columbus ready to start graduate school.  They will be working on issues related to bumble bee health and conservation, studying how landscape factors impact bumble bee health.  Recently, they got out to Waterman Farm on The Ohio State University Campus and were able to survey bumble bees foraging on a restored prairie patch.  Welcome to Columbus Iliana and Liam.

Common Eastern Bumble Bee (Bombus impatiens) on Partridge Pea (Chamaechrista fasciculata) at Waterman Farm, The Ohio State University

Welcome to the Strange Lab

Dr. Jamie Strange has studied bee health and genetics for over 20 years.  The research focus of the lab is to understand how pests, parasites, and pathogens impact bee populations and how population genetic tools can be applied to study changes to bee populations. Current projects include understanding the effects of landscape on bumble bee pathogen and parasite community, the impacts of urbanization on population diversity, and conservation of the Rusty-Patched Bumble Bee, a federally protected species.