Arrestment and detection of excreta by the terrestrial red mite Balaustium murorum (Erythraeidae) to mark suitable crevices for survival

ABSTRACTWe report an arrestment response by Balaustium murorum that is chemically mediated by excreta of conspecifics. Deutonymphs and adults arrest on saline extracts of their excreta and the excreta of each other. The arrestment could be mimicked by guanine, one of excreta’s principal components, but arrestment to it was lower than to excreta. Hypoxanthine, uric acid, xanthine, and adenine had arrestment properties, except for adenine in the adult. Adult appendages were removed by cauterizing. Without the palps, the adults did not arrest. Arrestment occurred with the first pair of legs removed, but with a decrease in response. Removal of the second pair of legs had no effect on arrestment. Thus, excreta act as an arrestant pheromone that allows mites to recognize suitable refuges under bark close to where pollen falls and arthropod prey are present. Detection of this arrestant pheromone occurs by using the palps and, to a lesser extent, the first pair of legs.