Behavioural and ecological aspects of nuptial flights of the termitophilous phorids Termitophilomyia zimbraunsi and Mesopathusa modesta (Diptera: Phoridae) in Zimbabwe

Nuptial flights of Termitophilomyia zimbraunsi were observed over three years (1990-1993) near the open chimney of an Odontotermes transvaalensis mound in Harare, Zimbabwe. Copulating phoretic pairs landed on the chimney; males quickly disengaged and flew away whilst females ran inside the vent and tore off their wing membranes. Agitated termite workers and soldiers swarmed the rim in a partially successful physical attempt to expel the phorids; the termites appeared to anticipate the threat of invasion. After acquiring the scent of the nest, female phorids ran underground to lay their large single eggs, probably in the hosts'fungus gardens. Nuptial flights occurred throughout the year but only in the early mornings, peaking in the hot dry season and being least in the hot wet season. The flights were highly temperature dependent (15.0-17.9 °), usually occurring at relatively low light intensities but across a wide range of humidities. Phoresy and sexual dimorphism in wings, mouthparts, food and division of labour in T. zimbraunsi are discussed, as is its termitophilous habit and the responses of termites to it.
Although the females of Mesopathusa modesta are apterous, nuptial flight behaviour is very similar to that of T. zimbraunsi. Neither phorid is host-specific, both species having been found on both Odontotermes latericius and O. transvaalensis mounds, although M. modesta is more common on O. latericius mounds.