Scientists have found that digger wasps of the genus Philanthus, so-called beewolves, house beneficial bacteria on their cocoons that guarantee protection against harmful microorganisms, in a new research.
The research was carried out by scientists of the Max Planck Institute for Chemical Ecology in Jena, Germany, in collaboration with researchers at the University of Regensburg and the Jena Leibniz Institute for Natural Product Research - Hans-Knoell-Institute.
They discovered that bacteria of the genus Streptomyces produce a cocktail of nine different antibiotics and thereby fend off invading pathogens.
Using imaging techniques based on mass spectrometry, the antibiotics could be displayed in vivo on the cocoon's exterior surface.
Moreover, it was shown that the use of different kinds of antibiotics provides an effective protection against infection with a multitude of different pathogenic microorganisms.
Thus, for millions of years, beewolves have been taking advantage of a principle that is known as combination prophylaxis in human medicine.
Martin Kaltenpoth and colleagues from the University of Wurzburg had already shown several years ago that beewolves form a symbiotic relationship with bacteria of the genus Streptomyces.
Female beewolves cultivate these bacteria in specialized antennal gland reservoirs and apply them to the ceiling of the brood cells.
Beewolf larvae later take up the bacteria and transfer the symbionts actively to their cocoons, thereby increasing their survival probability.
However, it has been unclear so far how the protection is achieved.
The team of scientists now discovered that the symbionts produce nine different antibiotic substances.
For the first time, the biologists were able to identify these substances directly in the natural environment, that is, on the beewolf cocoon.
By means of a novel technique of imaging mass spectrometry (LDI imaging), the Jena scientists could demonstrate that the antibiotics are primarily present on the exterior of the cocoon, reducing the risk of potentially harmful side-effects on the larvae.
"Astonishingly, little is known about the ecological importance of antibiotics in their natural environment. Supported by mass spectrometric imaging we are now able to better understand the natural role of antibiotic substances in the environment," said Ales Svatos, leader of the mass spectrometry research group.
The imaging techniques can help to provide important insights, especially into the exploration of symbiotic interactions.