Nicotine provides bumblebees with protection against parasites

Bumblebees benefit from nicotine and other substances in the plant nectar

02/18/2015

In nature, plants often deliberately use certain active ingredients to protect against predators. The plants produce so-called secondary metabolites as antibodies. For example, nicotine of the tobacco plant serves as a natural insecticide for protection. However, if bumblebees absorb smaller amounts of the toxin via the plant nectar, they suffer no damage and are additionally protected against parasites, US scientists report in the journal „Proceedings of the Royal Society B“.

The research team led by Leif Richardson from the Department of Biological Sciences at Dartmouth College, Hanover, New Hampshire, USA, has studied the effects of secondary metabolites on pollinators such as bees and bumblebees. „We hypothesized that secondary metabolites can reduce parasite infections in bees“, the scientists justified their investigations. The assumption has been clearly confirmed in the course of the study, which suggests that the plant's natural defense substances in bees and bumblebees act as a kind of protection against infection.

Propagation of parasites greatly reduced
In their experiments, the US researchers first infected individual bumblebees with intestinal parasites and then tested the effects of eight naturally occurring toxins on the spread of the parasites. The intake of low levels of nicotine and other secondary metabolites has greatly reduced the parasite burden, Richardson and colleagues say. The effect has been confirmed for the secondary metabolite anabasine, which is known to be a particularly potent toxin that can already cause low levels of death of rats and other rodents. Anabasin showed the most significant effect on the parasites, write the US researchers.

Nicotine for the protection of bees?
Although secondary metabolites have failed to rescue infected bumblebees, scientists believe that they play an important role in preventing parasite transmission. Accordingly, in view of the widespread infestation of pollinators by parasites and the associated bumblebee or bee mortality, the planting of plants with high levels of secondary metabolites could possibly be used selectively in future to protect the stocks. (Fp)