Use of optical density as a measure of Claviceps africana conidial suspension concentration

Sorghum ergot, caused by Claviceps africana, has remained a major disease problem in Australia since it was first recorded in 1996, and is the focus of a range of biological and integrated management research. Artificial inoculation using conidial suspensions is an important tool in this research. Ergot infection is greatly influenced by environmental factors, so it is important to reduce controllable sources of variation such as inoculum concentration. The use of optical density was tested as a method of quantifying conidial suspensions of C. africana, as an alternative to haemocytometer counts. This method was found to be accurate and time efficient, with possible applications in other disease systems.

Potential interactions between humans and non-breeding shorebirds on a subtropical intertidal flat

The primary aim of this study was to investigate whether bait harvesting, with all its inherent effects, occurring in the intertidal zone of a subtropical estuary, had an impact on a migratory shorebird, the eastern curlew Numenius madagascariensis. In a large-scale manipulative study (units of experiment were 1 ha plots), callianassid shrimp Trypaea australiensis populations were harvested simulating the technique (manual pumping) and the levels of harvesting intensity per unit area (347 shrimp per hectare per harvesting event) exhibited by bait-collectors in SE Australia and South Africa. It was found that at present levels of harvesting intensity per unit area (approximately 1% of standing stock removed per harvesting event) there is no threat to the stocks of Trypaea exploited by the curlews in Moreton Bay, Australia. However, the results show that the curlews themselves apply a considerable predation pressure on Trypaea. Based on the birds' foraging rates and densities, it was estimated that they would consume up to 100% of the initial Trypaea stock over the course of a non-breeding season (October to March). However, the stable seasonal trend in the density of the size-cohort of Trypaea preyed upon by the curlews indicates that the existing rates of predation are easily counterbalanced, e.g. through continuous density-dependent recruitment of these crustaceans. We suggest that this mechanism will provide for a stable foraging environment for both the shorebirds and bait collectors.

Idiopathic necrotizing dermatitis: Current management

Objectives: To identify and demonstrate necrotizing dermatitis in infancy; an uncommon, puzzling syndrome, in which anecdotal reporting and personal experience indicates that one third of cases may require skin grafting. Much informed discussion about the pathogenesis of this distressing syndrome centres on the role of spider envenomation; and in particular on the speculative role of the Australian White-tailed spider, Lampona cylindrata. Methods: We present here six cases of necrotizing dermatitis treated surgically at the Royal Children's Hospital and Mater Children's Hospital in Brisbane over the period from 1991 to 1999. Clinical history, surgical details and pathological investigations were reviewed in each case. Microbiological investigation of necrotic ulcers included standard aerobic and anaerobic culture. Result: Nocardia and Staphylococcus were cultured in two cases, but no positive bites were witnessed and no spiders were identified by either the children or their parents. All cases were treated with silver sulphadiazine creme. Two of the infants required general anaesthesia, excision debridement and split skin grafting. The White-tailed spider, Lampona cylindrata, does not occur in Queensland, but Lampona murina does; neither species has necrotizing components in its venom. Circumstantial evidence is consistent with this syndrome being due to invertebrate envenomation, possibly following arachnid bites. Conclusion: In our experience there is insufficient evidence to impute a specific genus as the cause, at this stage of scientific knowledge. If the offending creature is a spider, we calculate that the syndrome of necrotizing dermatitis occurs in less than 1 in 5000 spider bites.

The Thelastomatoidea (Nematoda : Oxyurida) of two sympatric Panesthiinae (Insecta : Blattodea) from southeastern Queensland, Australia: taxonomy, species richness and host specificity

The thelastomatoid fauna of two species of wood-burrowing cockroach (Blattodea, Blaberidae), Panesthia cribrata and Panesthia tryoni tryoni, from Lamington National Park, Australia, is described. The following eight new species and three new genera of thelastomatid are proposed: Bilobostoma exerovulva n. g., n. sp.; Cordonicola gibsoni n. sp.; Coronostoma australiae n. sp.; Desmicola ornata n. sp.; Hammerschmidtiella hochi n. sp.; Malaspinanema goateri n. g., n. sp.; Travassosinema jaidenae n. sp.; and Tsuganema cribratum n. g., n. sp. Additional data are given for Blattophila sphaerolaima and Leidynemella fusiformis. Of the 11 species reported, nine were found in P. cribrata and ten in P. tryoni tryoni. Such levels of thelastomatoid species richnessness in single host species are exceptional. Only the mole cricket, Gryllotalpa africana (23), and the domestic cockroach, Periplaneta americana (20), have higher reported richness. Three species, T jaidenae, C. australiae and D. ornata, were found either exclusively or significantly more prevalently in P tryoni tryoni than in R cribrata. Species of Travassosinema, Coronostoma and Desmicola have been found previously only in millipedes (Diplopoda), a fact that suggests that there is a greater degree of niche overlap between R tryoni tryoni and millipedes than for R cribrata.

Hematozoa of teleosts from Lizard Island, Australia with some comments on their possible mode of transmission and the description of a new hemogregarine species

Little is known of the blood parasites of coral reef fishes and nothing of how they are transmitted. We examined 497 fishes from 22 families, 47 genera, and 78 species captured at Lizard Island, Australia, between May 1997 and April 2003 for hematozoa and ectoparasites. We also investigated whether gnathiid isopods might serve as potential vectors of fish hemogregarines. Fifty-eight of 124 fishes caught in March 2002 had larval gnathiid isopods, up to 80 per host fish, and these were identified experimentally to be of 2 types, Gnathia sp. A and Gnathia sp. B. Caligid copepods were also recorded but no leeches. Hematozoa, found in 68 teleosts, were broadly hemogregarines of 4 types and an infection resembling Haemohormidium. Mixed infections (hemogregarine with Haemohormidium) were also observed, but no trypanosomes were detected in blood films. The hemogregarines were identified as Haemogregarina balistapi n. sp., Haemogregarina tetraodontis, possibly Haemogregarina bigemina, and an intraleukocytic hemogregarine of uncertain status. Laboratory-reared Gnathia sp. A larvae, fed experimentally on bruslitail tangs, the latter heavily infected with the H. bigemina-like hemogregarine, contained hemogregarine gamonts and possibly young oocysts up to 3 days postfeeding, but no firm evidence that gnathiids transmit hemogregarines at Lizard Island was obtained.