Surprising science behind bumblebee superfood
Sunflower family's spiny pollen vastly reduces prevalence of widespread parasite in bumblebees, increases production of queens

Date:
April 5, 2023
Source:
University of Massachusetts Amherst
Summary:
It's the spines. New research shows that the spiny pollen from
plants in the sunflower family (Asteraceae) both reduces infection
of a common bee parasite by 81 -- 94% and markedly increases
the production of queen bumble bees. The research provides
much-needed food for thought in one of the most vexing problems
facing biologists and ecologists: how to reverse the great die-off
of the world's pollinators.


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FULL STORY ==========================================================================
It's the spines. This is the conclusion of two new papers, led by
researchers at the University of Massachusetts Amherst, showing that
the spiny pollen from plants in the sunflower family (Asteraceae)
both reduces infection of a common bee parasite by 81 -- 94% and
markedly increases the production of queen bumble bees. The research,
appearing in Functional Ecologyand Proceedings of the Royal Society B: Biological Sciences,provides much-needed food for thought in one of the
most vexing problems facing biologists and ecologists: how to reverse
the great die-off of the world's pollinators.


========================================================================== Insect pollinators -- those flying, buzzing flitting bugs that help
fertilize everything from blueberries to coffee -- contribute upwards of
$200 billion in annual ecosystem services, worldwide. "We depend on them
for diverse, healthy, nutritious diets," says Laura Figueroa, incoming assistant professor of environmental conservation at UMass Amherst and
the lead author of the paper on pollen spines. However, many pollinators
are suffering an unprecedented decline, due to the widespread use of pesticides, habitat loss and other causes, and scientists around the
world are working diligently to figure out how to fight the apocalypse.

One of the big breakthroughs in helping pollinators, and especially bees,
is the discovery that certain species of flowers can help pollinators
resist disease infections, and that sunflowers are particularly effective
at combatting a widespread pathogen that lives in a bee's gut, called
Crithidia bombi.

But until now, no one knew why sunflowers were so effective at staving
off C.

bombi, or if other flowers in the sunflower family had the same pathogen- fighting powers.

Physics, not chemistry "We know that the health benefits from some foods
come from the specific chemicals in them" says Figueroa. "But we also
know that some foods are healthy because of their physical structure --
think of foods high in fiber." To discover how sunflowers help bumblebees withstand C. bombi, Figueroa and her team devised an experiment that
hinged on separating out the pollen's spiny outer shell from the chemical metabolites in the pollen's core. They then mixed the spiny sunflower
shell, with the chemistry removed, into the pollen fed to one batch
of bees, while another batch was fed wildflower pollen sprinkled with
sunflower metabolites and no sunflower shells.

"We discovered that the bees that ate the spiny sunflower pollen shells
had the same response as bees feeding on whole sunflower pollen, and
that they suffered 87% lower infections from C. bombi than bees feeding
on the sunflower metabolites," says Figueroa.

But that's not all. Bees fed pollen from ragweed, cocklebur, dandelion
and dog fennel -- all members of the sunflower family and with similarly
spiny pollen shells -- had low rates of C. bombi infection similar to
the bees who ate sunflower pollen -- which raises the possibility that
such disease-fighting medicinal effects may be common to plants in the sunflower family.

Food fit for a queen One of the counter-intuitive aspects of the new
research is that sunflower pollen is not in itself all that nutritious,
because sunflower pollen is low in protein. And while the pollen might
be great at protecting bumblebees from a gut pathogen like C. bombi,
it would be of little use to feed bumblebees sunflowers and relatives
if malnutrition resulted.

"It's no good curing the common cold if you starve the patient," says Lynn Adler, professor of biology at UMass Amherst and the senior author of the
paper looking at sunflower pollen and queen bee production. "We need to
look at the community level, as well as what's happening in bees' guts,
to know how to help them respond to stressful environments," says Adler.

One way to gauge a colony's health is by the number of queens it produces, because queens are the way a bumble bee colony passes on its genes to
the next generation. And queens aren't born, they're grown. Colonies
use the food resources they've collected to turn a small number of bee
larvae into daughter queens. Once the cold weather arrives, all the
workers and the old queen will die. The only bees that survive are the
new daughter queens. If they survive the winter, they will produce an
entirely new colony in the spring. The more queens a colony produces,
the higher the likelihood that a colony's genes be passed down through
many generations of bees.

To test the impact of sunflowers on colony health, Adler and her team
placed commercial colonies of bumblebees on twenty different farms in
Western Massachusetts, which grew varying amounts of sunflowers. Over
the course of several weeks, the team sampled the pathogens collecting
in their bees' guts, weighed the colonies to determine whether or not
they were thriving and counted the number of daughter queens.

"What we found is that infection decreased with increasing sunflower
abundance, and perhaps more importantly, queen bee production increased
by 30% for every order of magnitude increase in the availability of
sunflower pollen," says Rosemary Malfi, lead author of the paper and who completed the research as part of her postdoctoral work in Adler's lab.

Though there's more research to be done into exactly whysunflower
pollen benefits queen bees -- perhaps bumblebees have more energy
for reproduction if they're not fighting disease, or maybe C. bombi
impairs learning and foraging, so that reducing infection increases the
bees' ability to find food -- Adler says that "it's really exciting to
show that sunflower not only reduces disease, but positively affects reproduction." Next Steps Figueroa and Adler are quick to point out that
this research, which was supported by the US National Science Foundation
and Department of Agriculture, does not represent a solution to the
insect apocalypse. This research was conducted using just one common
species of bumblebees, which is not endangered.

More research needs to be done into how Asteraceae pollen affects other bumblebee species that are threatened. Nor is it known exactly how the
spiny Asteraceae pollen protects against C. bombi. But these initial
results are encouraging, and indicate that the sunflower family may
very well play a role in maintaining pollinator health, and, ultimately,
the health of our own food systems.

* RELATED_TOPICS
o Plants_&_Animals
# Agriculture_and_Food # Food_and_Agriculture # Seeds #
Mating_and_Breeding
o Earth_&_Climate
# Exotic_Species # Geochemistry # Ecology #
Environmental_Issues
* RELATED_TERMS
o Bee o Asteraceae o Ragweed o Pollination_management o
Bee_sting o Africanized_bee o Botany o Origin_of_life

========================================================================== Story Source: Materials provided by
University_of_Massachusetts_Amherst. Note: Content may be edited for
style and length.


========================================================================== Journal References:
1. Laura L. Figueroa, Alison Fowler, Stephanie Lopez, Victoria
E. Amaral,
Hauke Koch, Philip C. Stevenson, Rebecca E. Irwin, Lynn S. Adler.

Sunflower spines and beyond: Mechanisms and breadth of pollen
that reduce gut pathogen infection in the common eastern bumble
bee. Functional Ecology, 2023; DOI: 10.1111/1365-2435.14320
2. Rosemary L. Malfi, Quinn S. McFrederick, Giselle Lozano, Rebecca E.

Irwin, Lynn S. Adler. Sunflower plantings reduce a common gut
pathogen and increase queen production in common eastern bumblebee
colonies.

Proceedings of the Royal Society B: Biological Sciences, 2023;
290 (1996) DOI: 10.1098/rspb.2023.0055 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/04/230405160859.htm

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