While analyzing the plants chosen for the CHARISMA project some discoveries are made that might not be relevant to the project but is still quite interesting to share.
No, no, no, let’s not deviate to synthetic dyestuffs if nature already has made such ingenious repellents since much longer like camphor in Camphorwood, magnolias or cedar wood.
Nordamnacanthal works in the same way and it was detected in wild madder (Rubia peregrina L.) in hedge bedstraw (Galium mollugo L.) in lady’s bedstraw (Galium verum L.) and in madder (Rubia tinctorum L.).
The dye plant that drives away the Museum bug
But why drive off the beetle if it does not eats her?
Well, it was never the intension of the plant to produce lucidin-3-O-primeveroside for its own use but it was forced to produce this component by a bacterium called Rhizobium rhizogenes which is a soil bacterium that causes the ‘hairy root disease’ in rubia species. This bacterium infects the roots and causes them to produce a food source for themselves (lucidin-3-O-primeveroside). This component has a mutagenic effect on the roots that causes them to grow abnormally hairy.
Are there more bacteria who feed on dyes?
Yes. An studie made by the University of Warsaw have observed decolourization ande degradation of natural red dyes by microbial cause. Three bacteria; Bacillus cereus, bacillus vallismortis and bacillus subtilis who feed on purpurin and alizarin and even deteriorate silk textiles. It sounds very dramatic because these bacteria are present everywhere you can not clear the fibers of bacteria. But something simple as low humidity levels where this objects are stored is able to prevent this bacteria to be activated.
There have been cases of microbial decolourization in humid museums but I did not find any case where the varied carpet beetle has damaged any textile objects dyed with plants of the Rubiaceae family, but it is fascinating to note that rubia and galium species are already being used for centuries and that we now are observing that it was actualy quite a good choice.