New research finds surprising science behind bumble bee superfood

Spines are to blame. The spiny pollen from plants in the sunflower family (Asteraceae) both reduces infection of a common bee parasite by 81-94% and significantly boosts the production of queen bumble bees, according to two new studies led by researchers at the University of Massachusetts Amherst.

The study, which was published in Functional Ecology and Proceedings of the Royal Society B: Biological Sciences, offers much-needed food for thought on one of the most challenging issues facing ecologists and biologists today: how to stop the massive die-off of pollinators worldwide.

Around the world, the ecological services provided by insect pollinators—those flying, buzzing, darting critters that help fertilize everything from blueberries to coffee—amount to almost $200 billion annually. The primary author of the article on pollen spines, Laura Figueroa, is an incoming assistant professor of environmental conservation at UMass Amherst. "We depend on them for diverse, healthy, nutritious diets," she adds. However, because to the extensive use of pesticides, habitat degradation, and other factors, many pollinators are experiencing an unprecedented decrease, and experts worldwide are working furiously to find ways to stop the Armageddon.

The finding that some flower species can aid pollinators in resisting disease infections, and that sunflowers are especially good at fending off a common virus, Crithidia bombi, which dwells in a bee's stomach, is one of the major advances in aiding pollinators, and notably bees.

However, no one was aware of the reason why sunflowers were so successful in warding off C. bombi, or whether other members of the sunflower family also had the ability to combat pathogens.

not chemistry, but physics.

According to Figueroa, "We know that the health advantages from some foods come from the specific chemicals in them." However, we also understand that some meals are healthful due to their physical makeup, such as those high in fiber.

Figueroa and her colleagues designed an experiment that depended on isolating the chemical metabolites in the pollen's core from the spiny outer shell in order to learn how sunflowers aid bumble bees resist C. bombi. The pollen provided to one group of bees was then combined with the spiny sunflower shell that had had the chemical removed, whereas pollen from wildflowers that had been metabolized with sunflowers but no sunflower shells was fed to the second group of bees.

According to Figueroa, "We found that the bees who consumed the spiny sunflower pollen shells had the same reaction as bees consuming entire sunflower pollen and that they experienced 87% fewer C. bombi infections than bees consuming the sunflower metabolites.

That's not all, though. Bees fed pollen from plants in the sunflower family, including ragweed, cocklebur, dandelion, and dog fennel, all had low rates of C. bombi infection and similarly spiny pollen shells, raising the possibility that these disease-fighting medicinal effects may be present in all sunflower family plants.

The finest cuisine

The new research's counterintuitive findings include the fact that, due to its low protein content, sunflower pollen is not very nutritive in and of itself. And even while the pollen could be excellent at defending bumble bees against a gut infection like C. bombi, feeding bumble bees sunflowers and relatives would be of little value if starvation occurred.

According to Lynn Adler, professor of biology at UMass Amherst and principal author of the study examining sunflower pollen and queen bee production, "it's no good curing the common cold if you starve the patient." In order to understand how to assist bees in responding to stressful settings, according to Adler, we need to consider both the community level and what's going on within the bees' bodies.

The amount of queens a colony produces may be used to determine how healthy it is, as queens are how bumble bee colonies pass on their genetic makeup to the following generation. Moreover, queens mature rather than being born. Colonies develop a small number of bee larvae into daughter queens using the food resources they have gathered. All the employees as well as the elderly queen will pass away once the winter season approaches. The fresh daughter queens are the only bees that live. In the spring, they will create a brand-new colony if they make it through the winter. The possibility that a colony's genes will be handed down through many generations of bees increases when a colony produces more queens.

Adler and her team positioned commercial bumble bee colonies on 20 different farms in Western Massachusetts that produced variable amounts of sunflowers in order to assess the effect of sunflowers on colony health. The researchers weighed the colonies to see if they were growing, measured the amount of daughter queens, and collected the pathogens accumulating in the stomachs of their bees over the course of many weeks.

The study's lead author, Rosemary Malfi, concluded the investigation as a part of her postdoctoral work in Adler's laboratory. "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," she says.

Adler notes that "it's really exciting to show that sunflower not only reduces disease, but positively affects reproduction." There is still more research to be done to determine exactly why sunflower pollen benefits queen bees. Perhaps bumble bees have more energy for reproduction if they are not fighting disease, or perhaps C. bombi impairs learning and foraging so that reducing infection increases the bees' ability to find food.

Figueroa and Adler are keen to note that their research does not offer a cure for the end of the world due to insects. Only one common species of bumble bee, which is not threatened, was used in this study. The effects of Asteraceae pollen on other vulnerable bumblebee species require more study. The precise mechanism by which the spiny Asteraceae pollen defends against C. bombi is also unknown. However, these first findings are promising and suggest that the sunflower family may very well contribute to preserving the health of pollinators and, eventually, our own food chains.

Provided by University of Massachusetts Amherst