Traumatic sheep myiasis: A review of the current understanding.

Myiasis, or the infestation of live humans and vertebrate animals by dipterous larvae, is a health issue worldwide. The economic impact and potential threat to animal health and wellbeing of this disease under the animal husbandry sector is considerable. Sheep are a highly vulnerable livestock category exposed to myiasis (sheep strike), due to several unique predisposing factors that attract flies. The successful mitigation of this disease relies on a thorough understanding of fly population dynamics associated with the change in weather patterns and the evaluation of this disease through different branches of science such as chemistry, molecular biology, and microbiology. The present review provides a summary of the existing knowledge of strike in sheep, discussed in relation to the application of volatile organic compounds, metagenomics, and molecular biology, and their use regarding implementing fly control strategies such as traps, and to increase the resilience of sheep to this disease through improving their health and wellbeing.

Temperature variations in a parked vehicle.

There were two reasons why this work was conducted. The first was to help determine the time of death of suicide and homicide victims inside vehicles. The second was to investigate the serious threat to life of children or pets left in stationary vehicles on a hot summers day. This paper demonstrates that when a vehicle is parked in the sun, temperature levels in the cabin of the vehicle can be more than 20°C above the ambient temperature. A simple 'greenhouse' model for predicting the daily internal vehicle temperatures, using readily available local meteorological data, was developed. This statistical model was calibrated using meteorological data and temperature data collected on parked vehicles over several summer seasons. The model uses environmental temperature and radiation data as input, and is shown to predict cabin temperatures to within about 1°C. Both the data collected and the model developed show that the temperature inside the cabin of a black vehicle is typically 5°C higher than that inside a white vehicle on a hot summer day. Also lowering the driver's window of the vehicle by 2.5 cm typically reduces cabin temperatures by about 3°C, which is not sufficient to reduce significantly the safety concerns for children or pets left in parked vehicles.

Larviposition in the ovoviviparous blowfly Calliphora dubia.

This study examined larviposition in Calliphora dubia Macquart (Diptera: Calliphoridae), an ovoviviparous blowfly of considerable forensic importance in Australia. Females in the field carried 22-83 live larvae, exhibiting a strong linear relationship between female size and the number of live larvae carried. Females took just over 1 min (mean 67.7 ± 7.7 s, n = 54) to larviposit live larvae on or near fresh liver in the laboratory. Females laid larvae at a mean rate of 1.2 ± 0.1 larvae/s, with the fastest rate being 3.4 larvae/s. Most females (70%) laid live larvae only, but 14% laid larvae and eggs at the same time and 16% laid eggs only (none of the eggs laid were viable). Females laying only live larvae laid a mean of 53.7 ± 2.3 larvae, whereas those laying only eggs laid a mean of 48.6 ± 2.8 eggs on each occasion. None of the eggs laid were viable. Most females (86%) laid all their larvae in a single spot, even if they engaged in several bouts of laying live larvae. Nearly one-third of females did not lay all the live larvae in their ovisacs, but retained half of their complement of developed larvae. Females may be opting to spread their larvae across several carcasses in order to increase their survival and not to overcrowd small, ephemeral carcasses. The fact that a blowfly can lay either eggs or live larvae has enormous implications for the accurate determination of the post-mortem interval (PMI) as the presence of larvae derived from eggs laid on the body add 6-18 h to the PMI. This paper represents the first report of the ability of female calliphorids to resorb some of their own live larvae.

Temperature-dependent development of the parasitoid Tachinaephagus zealandicus on five forensically important carrion fly species.

The influences of temperature and host species on the development of the forensically important parasitoid Tachinaephagus zealandicus Ashmead (Hymenoptera: Encyrtidae) were studied at six constant temperatures in the range of 15-30 degrees C. T. zealandicus completed development successfully between 15 degrees C and 27 degrees C on five species of Calliphoridae, Calliphora albifrontalis Malloch, Calliphora dubia Macquart, Lucilia sericata Meigen, Chrysomya rufifacies Macquart and Chrysomya megacephala Fabricius. No adult parasitoids emerged from any of the host species reared at 30 degrees C. Temperature and host species significantly influenced development time, emergence success and progeny size. Development was significantly longer on Ch. megacephala and Ch. rufifacies at 18-24 degrees C and significantly longer on Ch. rufifacies and C. albifrontalis at 15 degrees C and 27 degrees C. Parasitoid emergence success was greatest at 21 degrees C, declined at the temperature extremes (15 degrees C and 27 degrees C) and was significantly lower on Ch. megacephala and Ch. rufifacies than on the three other host species. Progeny numbers per host pupa were highest at 21-24 degrees C, declined on either side of this temperature range and were significantly lower on L. sericata, Ch. rufifacies and Ch. megacephala than on either C. dubia or C. albifrontalis. An effect of host species on sex ratio was only observed at 27 degrees C, at which a higher proportion of T. zealandicus females emerged from Ch. megacephala and Ch. rufifacies than from the other host species. The thermal requirements for development (developmental thresholds, thermal constant, optimum temperature) of T. zealandicus in each host species were estimated using linear and non-linear models. Upper and lower developmental thresholds ranged between 29.90 degrees C and 31.73 degrees C, and 9.73 degrees C and 10.08 degrees C, respectively. The optimum temperature for development was estimated at between 25.81 degrees C and 27.05 degrees C. Given the significant effect of host species on development time, the use of parasitoid-host-specific developmental data in forensic application is recommended.

A global study of forensically significant calliphorids: implications for identification.

A proliferation of molecular studies of the forensically significant Calliphoridae in the last decade has seen molecule-based identification of immature and damaged specimens become a routine complement to traditional morphological identification as a preliminary to the accurate estimation of post-mortem intervals (PMI), which depends on the use of species-specific developmental data. Published molecular studies have tended to focus on generating data for geographically localised communities of species of importance, which has limited the consideration of intraspecific variation in species of global distribution. This study used phylogenetic analysis to assess the species status of 27 forensically important calliphorid species based on 1167 base pairs of the COI gene of 119 specimens from 22 countries, and confirmed the utility of the COI gene in identifying most species. The species Lucilia cuprina, Chrysomya megacephala, Ch. saffranea, Ch. albifrontalis and Calliphora stygia were unable to be monophyletically resolved based on these data. Identification of phylogenetically young species will require a faster-evolving molecular marker, but most species could be unambiguously characterised by sampling relatively few conspecific individuals if they were from distant localities. Intraspecific geographical variation was observed within Ch. rufifacies and L. cuprina, and is discussed with reference to unrecognised species.

Molecular identification of some forensically important blowflies of southern Africa and Australia.

One major aspect of research in forensic entomology is the investigation of molecular techniques for the accurate identification of insects. Studies to date have addressed the corpse fauna of many geographical regions, but generally neglected the southern African calliphorid species. In this study, forensically significant calliphorids from South Africa, Swaziland, Botswana and Zimbabwe and Australia were sequenced over an 1167 base pair region of the COI gene. Phylogenetic analysis was performed to examine the ability of the region to resolve species identities and taxonomic relationships between species. Analyses by neighbour-joining, maximum parsimony and maximum likelihood methods all showed the potential of this region to provide the necessary species-level identifications for application to post-mortem interval (PMI) estimation; however, higher level taxonomic relationships did vary according to method of analysis. Intraspecific variation was also considered in relation to determining suitable maximum levels of variation to be expected during analysis. Individuals of some species in the study represented populations from both South Africa and the east coast of Australia, yet maximum intraspecific variation over this gene region was calculated at 0.8%, with minimum interspecific variation at 3%, indicating distinct ranges of variation to be expected at intra- and interspecific levels. This region therefore appears to provide southern African forensic entomologists with a new technique for providing accurate identification for application to estimation of PMI.

Rate of development of Hydrotaea rostrata under summer and winter (cyclic and constant) temperature regimes.

The black carrion fly Hydrotaea rostrata Robineau-Desvoidy (Diptera: Muscidae) is a muscid, which occurs on approximately one-third of decomposing human corpses involved in homicide cases in south-western Australia. Work to date on its development rates is scant with only one published source available. The current study measured the precise developmental rates of this species using high repetition and sampling rates. A comparison was made of the developmental rates between constant and cyclic temperatures in winter and summer temperature regimes in south-western Australia. Developmental times for 90% of first stage larvae to emerge as adult flies are: summer constant, 21.6days, summer cyclic, 23.5 days, winter constant 64.5days and winter cyclic, 48.3 days. These data will allow forensic entomologists to make more accurate determinations of post-mortem intervals in cases where H. rostrata life history stages are present.

Forensic entomology: application, education and research in Western Australia.

Forensic entomology as a science and a tool for investigation has had slow beginnings in Australia. A number of small animal decomposition trials have been recorded in the literature but mostly from an ecological rather than a forensic entomology perspective. In the last 20 years, a number of more forensically orientated field trials on small pigs and some fly developmental trials in the laboratory have been conducted but lack any replication. The following article was presented at an international seminar to detail the current research in forensic entomology, the applications of forensic entomology in scene of crime (SOC) and homicide investigations and the education of police and judiciary in the discipline of forensic entomology in Western Australia over the last 10 years.

Stable fly, house fly (Diptera: Muscidae), and other nuisance fly development in poultry litter associated with horticultural crop production.

Poultry litter usage in horticultural crop production is a contributor to nuisance fly populations, in particular stable flies (Stomoxys calcitrans L.) and house flies (Musca domestica L.). Extrapolation of adult emergence data suggests that approximately 1.5 million house flies and 0.2 million stable flies are emerging on average from every hectare of poultry litter applied as a preplant fertilizer for vegetable production in Perth, Western Australia. To a lesser extent, sideband applications to established crops may allow for the development of 0.5 million house flies and 45,000 stable flies per hectare. However, up to 1 million house flies, 0.45 million lesser house flies, Fannia cannicularis L., and 11,000 stable flies per hectare may be produced from surface dressings of poultry litter associated with turf production. Other nuisance flies present in poultry litter included the false stable fly, Muscina stabulans (Fallén), bluebodied blowfly, Calliphora dubia Hardy, black carrion fly, Hydrotaea rostrata Robineau-Desvoidy, Australian sheep blowfly, Lucilia cuprina Wiedemann, and flesh flies (Sarcophagidae). Only house flies developed in poultry litter for the first 4 d after application in the field. Stable flies were not present in poultry litter until 4-7 d after application, and were the only fly species developing in litter > 9 d after application.

Effect of diet on the excretion profile of ivermectin in cattle faeces.

Two groups of 26 cattle (cross-bred, 3-8 years old, weight 450-650 kg) were placed onto 2 feed regimens, pasture-fed and grain-fed. The pasture-fed cattle were kept on irrigated pasture with hay supplement ad libitum, whereas the grain-fed cattle were kept in a feedlot and fed hay and lupin grain in a 40:60 ratio. Half the cattle within each feed group (n = 13) were given a subcutaneous injection of ivermectin (Ivomec) at the dose rate of 200 micrograms/kg liveweight. Over 5 times higher levels of ivermectin were excreted in the faeces of grain-fed cattle compared with pasture-fed (grazing) cattle. Peak excretion levels of 0.36 mg/kg (grain-fed) and 0.09 mg/kg (pasture-fed) of ivermectin were recorded at 6 and 8 days post-injection (dpi), respectively. Ivermectin was detected in faeces for up to 13 dpi (grain-fed) and 14 dpi (pasture-fed). Faecal pH in grain-fed cattle was more acidic (6.43) compared with pasture-fed cattle (7.28) and the levels of nitrogen in faeces from grain-fed cattle were higher (0.42%) compared with pasture-fed cattle (0.20%). Treatment with ivermectin had no influence on either the pH or nitrogen levels of faeces from either feed regimen. The impact of diet on the excretion profile of ivermectin is discussed in the context of studies attempting to demonstrate ecotoxic effects of ivermectin residues in cattle faeces on dung beetles.