When plants are attacked by predators or parasites, they cannot run away or hide. Instead they fight back by creating natural toxins which can cause some animals to stay away, or reduce the amount of damage done.

According to new research, these natural plant toxins may also help bees to fend off parasites as well as reduce the likelihood that parasites will be past on to others in the hive.

The researchers found that bees infected with a common parasite saw a reduction of up to 81 percent, in the presence of the parasite within seven days of infection if they absorbed the plant toxins.

“We found that eating some of these compounds reduced pathogen load in the bumblebee’s gut, which not only may help the individual bees, but likely reduced the pathogen Crithidia spore load in their feces, which in turn should lead to a lower likelihood of transmitting the disease to other bees,” said University of Massachusetts – Amherst evolutionary ecologist Lynn Adler in a statement.

According to Adler growers who depend on pollinators may be able to improve bee health and population by planting pollinator friendly gardens and hedgerows with plants that produce the “herbal remedies”.

“The more we look, the more we see that these compounds are in nectar and pollen too. With so many people looking at bee health these days, it’s taken a long time for us to realize that perhaps we should be paying attention to how floral secondary compounds mediate pollinator dynamics and their interactions with pathogens. Having bees consume these protective chemicals could be a natural treatment of the future,” said Adler.

Anecdotally, some honeybee growers already use one of the chemicals, thymol which is found in thyme plants, to treat mite infestations.

For their research, which appears in the journal Proceedings of the Royal Society B, the researchers infected 539 eastern bumblebees with the parasite Crithidia. That paradise has been found to shorten the lifespan of individual bees and reduce the colony’s ability to produce queens.

Bees from many different colonies were used to reduce the possibility of a colony specific response.

The infected bees were allowed to feed on one of eight nectar chemicals or on a control nectar. The chemicals used in the study were caffeine from coffee, citrus nectar, anabsine and nicotine from tobacco, thymol, gallic acid from buckwheat, aucubin and catalpol from turtlehead flowers and amygdalin from almond nectar.

After seven days the researchers measured the parasite loads in the intestines of their insect subjects and found a significant parasite reduction in the bees that had ingested the natural toxins.

“A lot of our spices and medicines come from plant secondary metabolites. Think of aspirin and chili powder. Because we’re big, we can eat a little chili powder on our food and it’s just a taste sensation. But for an insect the same dose might be fatal. That’s what the plant is counting on,” said Adler.

The researchers found no improvement when the infected bees were given a secondary treatment.