Monday, 27 April 2015

Parasite-Infected Bumblebees Seek out Flowers with Nicotine

 buff-tailed bumblebee eating nectar
 A buff-tailed bumblebee
Buff-tailed bumblebees (Bombus terrestris) that have been infected by parasites seek out flowers with nicotine in their nectar, according to a new study by researchers at the Royal Holloway University of London and Queen Mary University of London, UK.

Apparently, the nicotine in the flowers slows the progression of disease in infected bees but has harmful effects when consumed by healthy bees.

In their experiments, the scientists gave infected bumblebees two options, a sugar solution with nicotine and one without. The bees infected with Crithidia bombi  (the most well documented bumblebee parasite) were more likely to go for the nicotine-rich nectar than the healthy ones.

The scientists reported that the nicotine delayed the progress of the infection for a few days, with the bumblebees showing lower levels of parasites than the ones that had not consumed the nicotine nectar. However, their average life expectancy remained the same, meaning that the direct benefits of nicotine for the bee colony are still unknown.

An interesting side effect was that nicotine consumption suppressed the appetite of the infected bees much like smoking does in humans. Healthy individuals that consumed nicotine also showed shorter lifespans than those that did not consume any.

Bumblebees are not the only organism known to use nicotine to fight parasites. Another example is the house sparrow, which uses cigarette butts in its nest to protect it from mites.

"While it's clear that there is some benefit to nicotine consumption for parasite-infected bees, a key challenge now is to discover exactly how such natural medication limits the impact of the disease on the bees' society. Given the stresses placed on worldwide bee populations by disease, understanding how the bees themselves fight infection is key." said Dr David Baracchi, from the School of Biological and Chemical Sciences at QMUL and co-author of the study.

- Baracchi, D., Brown, M., & Chittka, L. (2015). Weak and contradictory effects of self-medication with nectar nicotine by parasitized bumblebees F1000Research DOI: 10.12688/f1000research.6262.1

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