Indirect effects of a non-target species, Pyrrhalta luteola (Chrysomelidae) on the biodeterioration of Brussels tapestries

Treatments to preserve artwork are usually designed to control for known target species. Nevertheless, indirect effects of non-target species may cause important biodeterioration. During the restoration of a series of Brussels tapestries preserved in the Abbey of Sacromonte (Granada, Spain), we studied one of the tapestries which presented a high degree of deterioration, principally large losses of material and color alterations. We found important biodeterioration effects produced by a non-target insect species, the beetle Pyrrhalta luteola (Chrysomelidae). We raised P. luteola beetles in the laboratory on different constituent materials to identify the effects of this insect on the tapestry. Results showed that beetle remains were mainly responsible for the chromatic changes. Although beetles did not consume textile materials, and had not direct effects in tapestry destruction, its presence indirectly affected the tapestry due to the higher mold-growth obtained in samples of materials with beetle remains. Based on these results, we propose some recommendations to consider control for these potential biodeterioration agents in artwork conservation programs.