Linked seasonality between a phoretic mite and its moth fly host (Parasitiformes: Mesostigmata and Diptera: Psychodidae)

Abstract

Phoresy is a widespread phenomenon in mites. It allows mesostigmatid mites that are associated with ephemeral habitats such as mammal dung to travel fast on larger animals that can detect a proper habitat from a greater distance. To address the gap in knowledge on phoresy in these mites, we examined host specificity in phoretic Mesostigmata associated with psychodid species and studied temporal dynamics to see if phoretic life cycles are synchronized with the host life cycle. Using a field collection of more than 2500 moth flies (Psychodidae) from eight localities in Norway, we found three out of 29 species carrying phoretic mites of two species: deutonymphs of Trachygamasus ambulacralis were phoretic on female Psychoda phalaenoides and both sexes of Psychoda grisescens, and adults of Iphidozercon gibbus were phoretic on females of Psychoda satchelli. All flies were species with larval development in vertebrate dung. Abundances of P. phalaenoides and T. ambulacralis were highly correlated, probably due to the two species exhibiting similar seasonal variations in abundance; both were significantly seasonal with a peak in August and September. Thus, T. ambulacralis infestation levels on P. phalaenoides appeared similar throughout the season. We discuss the implications for the life histories of the mites in question. Trachygamasus ambulacralis is first time recorded from Norway.