Microtrombidiid mite parasitization frequencies and attachment site preferences on brachyceran Diptera with specific reference to Therevidae (Asiloidea) and Tachinidae (Oestroidea)

Malaise trapping efforts for Therevidae (Diptera: Asiloidea) have uncovered a relationship between brachyceran Diptera and mites of the family Microtr ombidiidae (Acarina: Trombidioidea). Malaise trap samp les from a Juniperus forest in McKinley County, New Mexico produced 39 brachyceran families, 14 of which were parasitized by microtrombidiid mites in the genera Platytrom bidium Thor and Microtrombidium Haller. The frequency of parasitization was significantly higher in Tachinidae and Therevidae than the other 12 brachy ceran families with parasitized individuals. Mite loads, i.e., the number o f mites per individual, were also statistically different among families; s ome individuals were parasitized by as many as 21 mites. Mites preferred to attach at sites with soft, weakly sclerotized cuticle; the ventral cervica l area and the membrane behind the hind coxae were most densely infested. F emale Therevidae were attacked by mites at a significantly higher frequency than their male counterparts, but mite loads were similar. Insights into t he host-parasite relationships between the flies are discussed, but the pau city of both mite and dipteran information limits their interpretation.