Scrotal circumference of Australian beef bulls

Normal range for scrotal circumference in Australian beef bulls was established using more than 300,000 measurements of breed, management group, age, liveweight, and scrotal circumference. The data used were derived from Australian bull breeders and two large research projects in northern Australia. Most bulls were within 250 to 750 kg liveweight and 300 to 750 days of age. The differences between breeds and variances within breeds were higher when scrotal circumference was predicted from age rather than liveweight, because of variance in growth rates. The average standard deviation for predicted scrotal circumference from liveweight and age was 25 and 30 mm, respectively. Scrotal circumference by liveweight relationships have a similar pattern across all breeds, except in Waygu, with a 50 to 70 mm range in average scrotal circumference at liveweights between 250 and 750 kg. Temperate breed bulls tended to have higher scrotal circumference at the same liveweight than tropically adapted breeds. Five groupings of common beef breeds in Australian were identified, within which there were similar predictions of scrotal circumference from liveweight. It was concluded that liveweight and breed are required to identify whether scrotal circumference is within normal range for Australian beef bulls that experience a wide range of nutritional conditions.

Life history of Anomalococcus indicus (Hemiptera: Lecanodiaspididae), a potential biological control agent for prickly acacia Vachellia nilotica ssp indica in Australia

Babul scale Anomalococcus indicus Ramakrishna Ayyar, a major pest of Vachellia nilotica (L.f.) P.J.H. Hurter & Mabb. on the Indian subcontinent, has been identified as a potential biocontrol agent for prickly acacia V. nilotica subsp. indica (Benth.) Kyal. & Boatwr. in Australia and was imported from southern India for detailed assessment. The life history of A. indicus under controlled glasshouse conditions was determined as a part of this assessment. Consistent with other scale species, A. indicus has a distinct sexual dimorphism which becomes apparent during the second instar. Females have three instars, developing into sexually mature nymphs after 52 days. The generation time from egg to egg was 89 days. Females are ovoviviparous, ovipositing mature eggs into a cavity underneath their body. An average of 802 +/- 114 offspring were produced per female. Reproductive output was closely associated with female size; larger females produced more than 1200 offspring. Crawlers emerged from beneath the female after an indeterminate period of inactivity. They have the only life stage at which A. indicus can disperse, though the majority settle close to their parent female forming aggregative distributions. In the absence of food, most crawlers died within three days. Males took 62 days to develop through five instars. Unlike females, males underwent complete metamorphosis. Adult males were small and winged, and lived for less than a day. Parthenogenesis was not observed in females excluded from males. The life history of A. indicus allows it to complement other biological control agents already established on prickly acacia in Australia.

Gut-inhabiting yeasts from the gut of Australian passalid beetles

Passalidae (Polyphaga, Coleoptera) is a family of beetles with approximately 960 species that are distributed worldwide. Preliminary studies that characterized ascomycete and basidiomycete yeasts in the gut of these wood-eating beetles from the USA, Guatemala, and Thailand, demonstrated associations between certain yeast taxa and passalids. We extended the study to include yeasts and beetles from tropical forests near Cairns and Brisbane, Queensland, Australia. We isolated more than 1000 yeast strains from about 150 beetles belonging to 10 species. LSU and ITS rRNA markers were used to identify a subset of 250 yeast strains, which revealed that the gut of Australian passalids contained undescribed ascomycetes in the Debaryomyces, Dipodascus, Kazachstania, Ogataea, Scheffersomyces, Sugiyamaella, Spathaspora, Torulaspora, and Zygowilliopsis clades, as well as basidiomycetes in the genera Cryptococcus and Trichosporon. A close relative of Candida subhashii (Spathaspora clade) and the xylose-fermenting yeast Scheffersomyces stipitis were the most common species isolated in Queensland. These results agree with those of previous studies that showed a common association of xylose-fermenting yeasts in the gut of lignicolous insects. Species and higher taxa of yeasts, however, vary between Queensland passalids and those previously collected in distant regions.

The (Non)Effects of Lethal Population Control on the Diet of Australian Dingoes

Top-predators contribute to ecosystem resilience, yet individuals or populations are often subject to lethal control to protect livestock, managed game or humans from predation. Such management actions sometimes attract concern that lethal control might affect top-predator function in ways ultimately detrimental to biodiversity conservation. The primary function of a predator is predation, which is often investigated by assessing their diet. We therefore use data on prey remains found in 4,298 Australian dingo scats systematically collected from three arid sites over a four year period to experimentally assess the effects of repeated broad-scale poison-baiting programs on dingo diet. Indices of dingo dietary diversity and similarity were either identical or near-identical in baited and adjacent unbaited treatment areas in each case, demonstrating no control-induced change to dingo diets. Associated studies on dingoes' movement behaviour and interactions with sympatric mesopredators were similarly unaffected by poison-baiting. These results indicate that mid-sized top-predators with flexible and generalist diets (such as dingoes) may be resilient to ongoing and moderate levels of population control without substantial alteration of their diets and other related aspects of their ecological function.

Population genetics of Australian white sharks reveals fine-scale spatial structure, transoceanic dispersal events and low effective population sizes

Despite international protection of white sharks Carcharodon carcharias, important conservation parameters such as abundance, population structure and genetic diversity are largely unknown. The tissue of 97 predominately juvenile white sharks sampled from spatially distant eastern and southwestern Australian coastlines was sequenced for the mitochondrial DNA (mtDNA) control region and genotyped with 6 nuclear-encoded microsatellite loci. MtDNA population structure was found between the eastern and southwestern coasts (F-ST = 0.142, p < 0.0001), implying female reproductive philopatry. This concurs with recent satellite and acoustic tracking findings which suggest the sustained presence of discrete east coast nursery areas. Furthermore, population subdivision was found between the same regions with biparentally inherited micro satellite markers (F-ST = 0.009, p < 0.05), suggesting that males may also exhibit some degree of reproductive philopatry; 5 sharks captured along the east coast had mtDNA haplotypes that resembled western Indian Ocean sharks more closely than Australian/New Zealand sharks, suggesting that transoceanic dispersal, or migration resulting in breeding, may occur sporadically. Our most robust estimate of contemporary genetic effective population size was low and close to thresholds at which adaptive potential may be lost. For a variety of reasons, these contemporary estimates were at least 1, possibly 2, orders of magnitude below our historical effective size estimates. Population decline could expose these genetically isolated populations to detrimental genetic effects. Regional Australian white shark conservation management units should be implemented until genetic population structure, size and diversity can be investigated in more detail.

Efficacy of acibenzolar-S-methyl (Bion®) treatment of Australian commercial passionfruit, Passiflora edulis f. sp. flavicarpa, on resistance to Passionfruit woodiness virus (PWV) and activities of chitinase & β-1,3-glucanase

This greenhouse study investigated the efficacy of acibenzolar-S-methyl (Bion®) treatment of lower leaves of passionfruit, (Passiflora edulis f. sp. flavicarpa), on Passionfruit woodiness disease and activities of two pathogenesis-related proteins, chitinase and β-1,3-glucanase after inoculation with passionfruit woodiness virus (PWV). All Bion® concentrations reduced disease symptoms, but the concentration of 0.025 g active ingredient (a.i.)/l was the most effective, reducing disease severity in systemic leaves by 23, 29 and 30 compared with water-treated controls at 30, 40 and 50 days post inoculation (dpi) with PWV, respectively. Correspondingly, relative virus concentration as determined by DAS-ELISA in the upper, untreated leaves (new growth) above the site of inoculation at 50 dpi was reduced by 17 and 22 in plants treated with 0.025 and 0.05 g a.i./l, respectively. Bion® treatment and subsequent inoculation with PWV increased chitinase and β-1,3-glucanase activities in the new leaves above the site of inoculation at 30 dpi with PWV. It was concluded that optimal protective Bion® treatment concentrations were 0.025 and 0.05 g a.i./l.

The Use of Australian Honey in Moist Wound Management

This project has investigated the correlation between antimicrobial activity and the non-peroxide activity of particular Leptospermum-derived honeys. Initial investigations tested the efficacy of these honeys against one particular bacteria (Staphylococcus aureus), while later studies assessed the effect of this honey on a range of food pathogens, animal pathogens (e.g. in mastitis) and human pathogens (e.g. golden Staph). Using honeys sourced from around Australia and screened against several reference microorganisms, the anti-microbial potency of one particular Australian honey (from Leptospermum polygalifolium) was shown to be comparable to NZ Manuka honey (from L.scoparium). The results of this screening of active honeys against pathogenic bacteria has supported the registration of honey by Capilano Honey Limited as a “Drug” with the Therapeutic Goods Administration based on its antimicrobial activity.