Behaviour of pill millipedes can be affected by external marking

Abstract

External or internal marking techniques are often used in various studies of invertebrates to distinguish individuals. Although the potential influence of marking agents on survival is often evaluated, a possible effect on behaviour is usually neglected. We evaluated the influence of two external marking agents (nail polish and bee marker) on behaviour of the pill millipedes, Glomeris tetrasticha, in laboratory. Behaviour was examined from two points of view: (1) specific expressions of behaviour (feeding, exploring, resting and hiding) through 24 hours and (2) activity through 24 hours. The nine-day experiment compared be- haviour between groups marked with nail polish or bee marker and the control group. Although there was no observed influence of marking on survival, there was an evident influence on the frequency of feeding, resting and hiding. An effect on frequency of exploring was significant in the marker-marked group only. Marked individuals of G. tetrasticha also differed from the control group in overall activity. They were less active overall and preferred resting and hiding. G. tetrasticha were found to be quite active during almost the whole day in the laboratory, with maximum feeding behaviour in the early morning.