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.

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.