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

摘要

Studies on the lucerne flea, Sminthurus viridis (L.) and other Collembolaudof the Tasmanian culture steppe covered two main aspects. These were (i)udinvestigations into the biological control of S. viridis in pasture withudparticular reference to mite predators and (ii) the identification,uddistribution, phenology and pest status of other Collembola inhabitatingudthe culture steppe, particularly the species of pastures and field crops.ud(i) Biological control of S. viridisudgurveys of the distribution of S. viridis and the predatory bdellid mite,udBdellodes lapidaria (Kramer) showed that the mite was uncommon in partsudof north-west Tasmania where the pest status of S. viridis was high.udAdditional investigations at monitored sites in north-west Tasmania whereudB. lapidaria was present failed to indicate any significant predator-preyudrelationship between B. lapidaria, S. viridis or other surface-activeudCollembola. Data obtained on the distribution and phenology of otherudspecies of predatory mites from the families Bdellidae, Parasitidae andudAnystidae also provided no evidence that any of these were having audsignificant impact on S. viridis populations. The poor control of S.udviridis by established predators led to the initiation of a programme toudintroduce another predator of S. viridis, the bdellid Neomologusudcapillatus (Kramer) from Europe. The predator was successfullyudestablished in north-west Tasmania where B. lapidaria is uncommon.ud.(ii) Identification, distribution, phenology and pest status ofudCollembola in the Tasmanian culture steppe.udSurveys and population monitoring at selected sites in improved pasturesudenabled the identification of 51 surface-active species from 6 familiesudand 10 euedaphic species from 3 families. Comparison of the fauna ofudboth the high and low rainfall pasture ecotypes of the State showed thatudmost surface-active species occurred in both ecotypes, althoughuddifferences between the two were reflected by differences in theudadaptability of some species as revealed by variation in theirudfrequencies of occurrence and phenology. Species were shown to haveudregular annual cycles, however, there was variation in patterns ofudseasonal periodicity, and temperature and rainfall were shown to have audsignificant impact on populations.udSurveys of field crops resulted in the identification of 26 surfaceactiveudspecies and only two of these were not collected from pasture.udDiffering preferences by some species for either the crop or pastureudhabitat were noted and there was an indication of differing preferencesudby some species for crops in high and low rainfall areas. Field andudlaboratory studies on the pest status of Collembola in field crops showedudthat S. viridis was the most injurious, although field damage by theudgarden springtail, Bourletiella hortensis (Fitch) and root-feedingudOnvchiurus spp. was recorded.udA key is given to the species identified in the study including separateudkeys to Onychiuridae and Hvpocrastrura spp.