Studies on lucerne flea, Sminthurus viridis (L.) (Collembola:sminthuridae) and other Collembola in the Tasmanian culture steppe

Studies on the lucerne flea, Sminthurus viridis (L.) and other Collembola of the Tasmanian culture steppe covered two main aspects. These were (i) investigations into the biological control of S. viridis in pasture with particular reference to mite predators and (ii) the identification, distribution, phenology and pest status of other Collembola inhabitating the culture steppe, particularly the species of pastures and field crops. (i) Biological control of S. viridis gurveys of the distribution of S. viridis and the predatory bdellid mite, Bdellodes lapidaria (Kramer) showed that the mite was uncommon in parts of north-west Tasmania where the pest status of S. viridis was high. Additional investigations at monitored sites in north-west Tasmania where B. lapidaria was present failed to indicate any significant predator-prey relationship between B. lapidaria, S. viridis or other surface-active Collembola. Data obtained on the distribution and phenology of other species of predatory mites from the families Bdellidae, Parasitidae and Anystidae also provided no evidence that any of these were having a significant impact on S. viridis populations. The poor control of S. viridis by established predators led to the initiation of a programme to introduce another predator of S. viridis, the bdellid Neomologus capillatus (Kramer) from Europe. The predator was successfully established in north-west Tasmania where B. lapidaria is uncommon. .(ii) Identification, distribution, phenology and pest status of Collembola in the Tasmanian culture steppe. Surveys and population monitoring at selected sites in improved pastures enabled the identification of 51 surface-active species from 6 families and 10 euedaphic species from 3 families. Comparison of the fauna of both the high and low rainfall pasture ecotypes of the State showed that most surface-active species occurred in both ecotypes, although differences between the two were reflected by differences in the adaptability of some species as revealed by variation in their frequencies of occurrence and phenology. Species were shown to have regular annual cycles, however, there was variation in patterns of seasonal periodicity, and temperature and rainfall were shown to have a significant impact on populations. Surveys of field crops resulted in the identification of 26 surfaceactive species and only two of these were not collected from pasture. Differing preferences by some species for either the crop or pasture habitat were noted and there was an indication of differing preferences by some species for crops in high and low rainfall areas. Field and laboratory studies on the pest status of Collembola in field crops showed that S. viridis was the most injurious, although field damage by the garden springtail, Bourletiella hortensis (Fitch) and root-feeding Onvchiurus spp. was recorded. A key is given to the species identified in the study including separate keys to Onychiuridae and Hvpocrastrura spp.