For their study, the scientists removed the yeast fungi from the flowers of some hellebore plants. The temperature of the nectar immediately dropped off sharply. In a second experiment, they mixed young, yeast-free flowers with the fungus and measured the temperature of the nectar, the air temperature inside the flowers and the ambient air temperature. The researchers discovered that the nectar warmed up as a result of the yeast activity and the temperature difference between the flower interior and the environment also increased.
The yeast is actually considered a parasite, the scientists write: It reduces the sugar content in the nectar that the plant produces for possible pollinators. Thus, the sweet plant juice loses its appeal for the food-seeking insects. However, according to the researchers, this interpretation implies that neither plants nor pollinators benefit from the presence of yeast. However, this is not the case: the insects visit the Stinking hellebore not primarily because of the nectar, but because of the heat in their calyx. This creates a "win-win situation" for the plants and the pollinators thanks to the parasites.Carlos Herrera (Estación Biológica de Doñana, Seville) Proceedings of The Royal Society B, online pre-publication, doi: 10.1098 / rspb.2009.2252 ddp / wissenschaft.de? Regula Brassel advertisement