Biology and Host Specificity of Chamaesphecia mysiniformis (Lepidoptera: Sesiidae), a Potential Biological Control Agent of Marrubium vulgare (Lamiaceae) in Australia

The biology of the rhizophagous clearwing moth Chamaesphecia mysiniformis Rambur and its specificity to Marrubium vulgare L. (Lamiaceae) (horehound), a serious introduced weed in southern Australia, were studied in France. Adults emerged in late spring during the morning and began mating on the same day, usually in the mid to late afternoon. Eggs were laid among flower clusters, with females laying an average of 96 2.41 (range, 1-268) with an overall hatch success of 79%. In no-choice, host-specificity tests, first instar larvae attacked only four species of Marrubium, along with Ballota nigra L. and Stachys arvensis L. This high level of specificity and the high mortality of the target plant in its native range make this moth a promising biological control agent of horehound in Australia.     

Systematics of AustralianLepidium species (Brassicaceae) and implications for their origin: Evidence from IEF analysis of Rubisco

Variation in subunit polypeptide composition of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from native AustralianLepidium taxa was analyzed by isoelectric focusing (IEF). Species of grexMonoplocoidea on the one hand, and species of gregesPseudoruderalia andPapillosa on the other, were well separated by Rubisco IEF patterns. The protein data suggest grexMonoplocoidea to be placed in sect.Monoploca whereas gregesPseudoruderalia andPapillosa should be integrated into sect.Dileptium. We suggest that the Rubisco type of American and/or AsianLepidium species was contained in those plants migrating to Australia and evolving into the recent native Australian species. Fossil pollen records and vegetation history indicate that the origin ofLepidium in Australia was restricted to the late Tertiary of Quaternary. Data presented in this study fit best with an immigration by long-distance dispersal of seeds by birds from Asia and/or from South America.     

Changes in mammal populations in relatively intact landscapes of Kakadu National Park,Northern Territory,Australia

A previous study ( Braithwaite & Muller 1997 ) reported substantial declines in mammal abundance over the period 1986–1993 for a large study area (300 km²) within Kakadu National Park in the tropical savannas of northern Australia. This decline was reported as being a ‘natural’ response to fluctuating groundwater levels, driven by runs of poor wet seasons. We resampled mammals in this area in 1999, following a series of unusually good wet seasons, and examined the prediction that mammal numbers should have recovered. Increases in abundance were evident for four species: the smallest dasyurid (red‐cheeked dunnart Sminthopsis virginiae) and the three smallest rodents (delicate mouse Pseudomys delicatulus, western chestnut mouse Pseudomys nanus and grassland melomys Melomys burtoni). In contrast, the abundance of all mammals combined and that for seven individual mammal species (northern quoll Dasyurus hallucatus, fawn antechinus Antechinus bellus, common brushtail possum Trichosurus vulpecula, northern brown bandicoot Isoodon macrourus, dusky rat Rattus colletti, black‐footed tree‐rat Mesembriomys gouldii and pale field rat Rattus tunneyi) continued to decline. The decline in abundance of these mammal species is consistent with limited observations elsewhere in northern Australia. Although far from conclusive, these observations suggest that the biota of the vast relatively undisturbed tropical savannas can no longer be assumed to be intact nor safe. Further research is needed to test this possible pattern of decline and, if confirmed, to identify and ameliorate the processes contributing to it.     

Global soil ciliate (Protozoa, Ciliophora) diversity: a probability-based approach using large sample collections from Africa, Australia and Antarctica

Large sample collections from Africa (92 samples), Australia (157) and Antarctica (90) were investigated for soil ciliates using the non-flooded Petri dish method, which re-activates the ciliates' resting cysts from air-dried samples. Species were determined from life and by silver impregnation. The African samples were the richest, containing 507 species (240 undescribed,=47%), followed by the Australian (361 species, 154=43% undescribed) and the Antarctic (95 species, 14=15% undescribed) samples. The percentage of new species/sample was consistently low, viz. 4–8% on average, indicating that new species were considerably undersampled relative to described ones, very probably due to methodological shortcomings, i.e. usually only cysts of the more euryoecious species could be reactivated. Thus, a probability theory-based statistical approach was applied to the data sets to compensate for the underestimated number of undescribed species. This procedure indicated that, depending on the region, 70–80% of the soil ciliates are still unknown and global soil ciliate diversity amounts to at least 1330–2000 species. Several indicators, especially the constant rate at which new species have been found during a 20-year period of intensive research, suggest that this estimate is conservative. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ecological role of hypogeous ectomycorrhizal fungi in Australian forests and woodlands

The Australian continent is characterised by a harsh climate and highly weathered, nutrient-poor soils. Trees and shrubs in these stressful environmental conditions typically form ectomycorrhizae with a variety of fungi, many of which form hypogeous (underground) fruit-bodies. The total number of hypogeous fungi Australia-wide is unknown, although recent systematic studies in the far south-eastern corner of the country suggest that they may number well over a thousand. Similar surveys elswhere are urgently required to clarify the situation. The precise ecological role of many hypogeous fungi remains to be determined, although most presumably facilitate nutrient and water uptake on behalf of their mycorrhizal partners. Others may also protect their plant host from root pathogens. One key function of hypogeous fungi is the role their fruit-bodies play as a food resource for a large range of terrestrial mammals. For a few animals, hypogeous fungi form the single most important dietary item year-round, whereas for others they may only be of seasonal or supplementary value. The extent to which fungi form part of the diet of any mammal species is reflected in the various levels of adaptation toward acquiring, then processing and digesting these cryptic and nutritionally challenging foodstuffs.     

Responses of billabong rotifer communities to inundation

Daily plankton collections were taken from a billabong of the River Murray for two weeks prior to inundation in March 1990, and continued for ten days after flooding. Quantitative responses of the plankton community and the component species were analysed against measured environmental variables and between species. Rotifers and copepod nauplii were the predominant net plankton (> 53 µm). Significant negative or positive responses to inundation were detected for most common taxa of 63 rotifer species recorded. A four-fold dilution from intrusion of river water masked rapid population increases. Opportunistic responses to inundation appear to be a survival strategy in the highly unpredictable billabong environment.