Egg parasitoids of tabanids in Manitoba: Prevalence, taxonomy, behaviour, and use of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to establish host-parasite interrelationships.

摘要

Tabanid egg masses were collected from different locations in Manitoba (Canada) during the summers of 1996--2000. Two scelionid parasitoids (Telenomus species A and B) were reared from horse fly egg masses (Hybomitra spp.) and another scelionid parasitoid (Telenomus species C) along with one trichogrammatid parasitoid (Trichogramma semblidis (Aurivillius)) were reared from deer fly egg masses (Chrysops spp.). The taxonomy and host-associations of ten Telenomus species recorded from eggs of Tabanidae in different geographical regions of the world were reviewed and type specimens of these species were compared with specimens reared in Manitoba. Based on characters on the metasoma, mating behaviour and host partitioning, three scelionid parasitoids reared from tabanid eggs in Manitoba were undescribed. These three species were described and an identification key for New World species (including new species from Manitoba, and one Palaearctic species) was provided.; Host specificity, host finding strategies, host partitioning and emergence patterns of parasitoids, mating and oviposition behaviours, acceptance of stored and frozen tabanid egg masses by parasitoids, parasitoid development inside the host, and overwintering strategies of tabanid egg parasitoids were studied.; To study host-parasitoid interactions, it was necessary to identify the tabanid egg masses. Rearing and a molecular technique were examined to identify tabanid egg masses. The molecular method was a fast and accurate technique to associate adults of tabanids with their egg masses. Polymerase chain reaction (PCR) and subsequent restriction fragment polymorphism (RFLP) analysis were used to differentiate 35 species of adult horse flies and deer flies (Diptera: Tabanidae) representing five genera [Atylotus (1 sp.), Chrysops (11 spp.), Haematopota (1 sp.), Hybomitra (17 spp.), and Tabanus (5 spp.)] from Manitoba. Initial PCR-RFLP analysis using amplicons of two mitochondrial tRNA genes and the internal transcribed spacer (ITS) of nuclear ribosomal DNA (rDNA) could be used to distinguish only a limited number of species from others in the collection. However, PCR-RFLP analysis using the rDNA intergenic spacer (IGS) between the 28S and 18S rRNA genes generated restriction fragment profiles that could be used to differentiate all 35 species from one another. There was a small degree of intraspecific variation among fragment patterns observed when multiple individuals of a species were examined. The rDNA IGS therefore provided a target sequence with sufficient variation to identify individual tabanids to the species level. (Abstract shortened by UMI.)