Seasonal abundance and infestation of deutonymphs ofUropoda orbicularis(Müller, 1776) (Acari: Mesostigmata) phoretic on coprophilous beetles (Scarabaeidae, Geotrupidae, Aphodiidae, Hydrophilidae, Histeridae)

Seasonal abundance and rates of infestation of deutonymphs of Uropoda orbicularis (Müller, 1776) on various groups of coprophilous beetles (Scarabaeidae, Geotrupidae, Aphodiidae, Hydrophilidae and Histeridae) are reported. Beetles and mites were collected using pitfall traps placed in a pasture situated in western Poland. The results have shown that deutonymph infestation varies among beetle families, and that season is an important factor affecting mite infestation. The highest rates of infestation were recorded for Scarabaeidae and the lowest values for Hydrophilidae. Scarabaeidae were most numerous during late May/early June when deutonymph abundance was the highest which may explain why they carried the largest numbers of phoretic deutonymphs. Season affected U. orbicularis directly as well as indirectly, due to beetle abundance. Changes in beetle and phoretic deutonymph abundances were similar. Phoretic deutonymphs were observed early in the season on the first beetle specimens collected, however during autumn their numbers decreased markedly even though abundance of carriers was still high. The results have shown that phoretic mite abundance and infestation on carriers may be influenced by seasonal factors to a high degree. This fact should be taken into account by determining mite preferences towards their carriers.