A Survey of Microbial, Insect and Nematode Parasites of Tipulidae (Diptera) Larvae in North-East England

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Abstract
The parasites of Tipula spp. larvae were surveyed, principally at 4 locations between Sept. 1973 and July 1974. The most common host species was T. paludosa Meigen. Some new parasites were recorded together with previously-recorded parasites in new hosts. It is concluded that the parasites were not a highly significant cause of larval mortality. The most common parasites were gregarines and coccidia, but there was little evidence to suggest that they affected the well-being of their hosts. There were significant differences in the percentage of larvae infected with protozoa between host species, between locations and between areas at the same location. Some possible reasons for these differences are discussed. Oxyuroid nematodes also had little apparent effect on their hosts. Larvae parasitized by Tipula iridescent virus, Tipula nuclear polyhedrosis virus, bacteria, fungi, microsporidia, mermithids, tachinids or phorids were rarely found. The viruses, mermithids and tachinids usually killed their hosts and are potential biological control agents. The other parasites require further evaluation to determine their effect on the host. For any parasite to be a successful biological control agent it will be necessary to induce infections when the tipulid larvae are in the earlier instars, and in larger proportions of the populations than normally occurs under natural conditions.