Differences in the pattern of turn alternation between juveniles and adults of Armadillo officinalis Dumèril, 1816 (Isopoda, Oniscidea) in response to substrate-borne vibrations

Abstract

In this study, we focused on the relationship existing between the phenomenon of alternating turns and substrate-borne vibrations in woodlice, utilizing Armadillo officinalis as an experimental behavioral model. A T-maze with multiple exits was used to collect information on the pattern of turn alternation in (i) adult individuals of A. officinalis exposed and (ii) non-exposed to micro-vibrations, and (iii) juveniles of A. officinalis exposed to micro-vibrations. Turn alternation was assessed as the number of times that an animal turned on the opposite side in the T-maze. Our best model pointed out a statistically significant increased expected number of alternating turns for both groups of adult individuals, non-exposed and exposed to micro-vibrations, compared to exposed juveniles. Adults of A. officinalis seem to be very reactive to substrate-borne vibrations, unlike juveniles. This reactivity might be related to a defense mechanism developed as an evolutionary adaptation to the xeric environment, increasing progressively from the juvenile condition until the adult state. This feature might also fit into a complex network of inter- and intraspecific communication mediated by substrate-borne vibrations, like in insects.