Calliphora Stygia Research Articles

Priority effects and density promote coexistence between the facultative predator Chrysomya rufifacies and its competitor Calliphora stygia

Highly competitive ephemeral resources like carrion tend to support much greater diversity relative to longer-lived resources. The coexistence of diverse communities on short-lived carrion is a delicate balance, maintained by several processes including competition. Despite this balance, few studies have investigated the effect of competition on carrion, limiting our understanding of how competition drives coexistence. We investigated how priority effects and larval density influence coexistence between two blowfly species, the facultative predator Chrysomya rufifacies and its competitor Calliphora stygia, which occupy broadly similar niches but differ in their ecological strategies for exploiting carrion. We examined how adult oviposition, larval survival, developmental duration, and adult fitness were affected by the presence of differently aged heterospecific larval masses, and how these measures varied under three larval densities. We found C. rufifacies larval survival was lowest in conspecific masses with low larval densities. In heterospecific masses, survival increased, particularly at high larval density, with priority effects having minimal effect, suggesting a dependency on collective exodigestion. For C. stygia, we found survival to be constant across larval densities in a conspecific mass. In heterospecific masses, survival decreased drastically when C. rufifacies arrived first, regardless of larval density, suggesting C. stygia is temporally constrained to avoid competition with C. rufifacies. Neither species appeared to completely outcompete the other, as they were either constrained by density requirements (C. rufifacies) or priority effects (C. stygia). Our results provide new mechanistic insights into the ecological processes allowing for coexistence on a competitively intense, ephemeral resource such as carrion.

Transcriptomics reveal the molecular underpinnings of chemosensory proteins in Chlorops oryzae

BackgroundChemosensory proteins are a family of insect-specific chemical sensors that sense specific chemical cues and regulate insect behavior. Chemosensory proteins have been identified and analyzed in many insect species, such as Drosophila melanogaster, Bactrocera dorsalis and Calliphora stygia. This research has revealed that these proteins play a crucial role in insect orientation, predation and oviposition. However, little is known about the chemosensory proteins of Chlorops oryzae, a major pest of rice crops throughout Asia.ResultsComparative transcription analysis of the genes of Chlorops oryzae larvae, pupae and adults identified a total of 104 chemosensory genes, including 25 odorant receptors (ORs), 26 odorant-binding proteins (OBPs), 19 ionotropic receptors (IRs), 23 gustatory receptors (GRs) and 11 sensory neuron membrane proteins (SNMPs). The sequences of these candidate chemosensory genes were confirmed and used to construct phylogenetic trees. Quantitative real-time PCR (qRT-PCR) confirmed that the expression of candidate OR genes in different developmental stages was consistent with the fragments per kilobase per million fragments (FPKM) values of differentially expressed genes (DEGs).ConclusionsThe identification of chemosensory genes in C. oryzae provides a foundation for the investigation of the function of chemosensory proteins in this species, which, in turn, could allow the development of new, improved methods of controlling this pest.

Effect of temperature on the rate of ageing: an experimental study of the blowfly Calliphora stygia.

All organisms age, the rate of which can be measured by demographic analysis of mortality rates. The rate of ageing is thermally sensitive in ectothermic invertebrates and we examined the effects of temperature on both demographic rates of ageing and on cellular senescence in the blowfly, Calliphora stygia. The short lifespan of these flies is advantageous for demographic measurements while their large body size permits individual-based biochemical characterisation. Blowflies maintained at temperatures from 12°C to 34°C had a five to six-fold decrease in maximum and average longevity, respectively. Mortality rates were best described by a two-phase Gompertz relation, which revealed the first-phase of ageing to be much more temperature sensitive than the second stage. Flies held at low temperatures had both a slower first-phase rate of ageing and a delayed onset of second-phase ageing, which significantly extended their longevity compared with those at high temperatures. Blowflies that were transferred from 29°C to 15°C had higher first-phase mortality rates than those of flies held at constant 15°C, but their onset of second-phase ageing was deferred beyond that of flies held constantly at this temperature. The accumulation of fluorescent AGE pigment, a measure of cellular oxidative damage, increased steadily over time in all blowflies, irrespective of the temporal pattern of mortality. Pigment accumulated steadily during periods of ‘negligible senescence’, as measured by minimal rate of mortality, and the rate of accumulation was significantly affected by temperature. Thus accumulation of AGE pigment is more representative of chronological age than a reflection of biological age or a cause of mortality.

Examination of forensic entomology evidence using computed tomography scanning: case studies and refinement of techniques for estimating maggot mass volumes in bodies

A new technique has recently been developed for estimating the volume of maggot masses on deceased persons using post-mortem CT scans. This allows volume to be measured non-invasively and factored into maggot mass temperature calculations for both casework and research. Examination of admission scans also allows exploration of entomological evidence in anatomical areas not usually exposed by autopsy (e.g. nasal cavities and facial sinuses), and before autopsy disrupts the maggot distribution on a body. This paper expands on work already completed by providing the x-ray attenuation coefficient by way of Hounsfield unit (HU) values for various maggot species, maggot masses and human tissue adjacent to masses. Specifically, this study looked at the HU values for four forensically important blowfly larvae: Lucilia cuprina, L. sericata, Calliphora stygia and C. vicina. The Calliphora species had significantly lower HU values than the Lucilia species. This might be explained by histological analysis, which revealed a non-significant trend, suggesting that Calliphora maggots have a higher fat content than the Lucilia maggots. It is apparent that the variation in the x-ray attenuation coefficient usually precludes its use as a tool for delineating the maggot mass from human tissue and that morphology is the dominant method for delineating a mass. This paper also includes three case studies, which reveal different applications for interpreting entomological evidence using post-mortem CT scans.

Effect of morphine on the growth rate of Calliphora stygia (Fabricius) (Diptera: Calliphoridae) and possible implications for forensic entomology

Insect specimens collected from decomposing bodies enable forensic entomologists to estimate the minimum post-mortem interval (PMI). Drugs and toxins within a corpse may affect the development rate of insects that feed on them and it is vital to quantify these effects to accurately calculate minimum PMI. This study investigated the effects of morphine on growth rates of the native Australian blowfly, Calliphora stygia (Fabricius) (Diptera: Calliphoridae). Several morphine concentrations were incorporated into pet mince to simulate post-mortem concentrations in morphine, codeine and/or heroin-dosed corpses. There were four treatments for feeding larvae; T 1: control (no morphine); T 2: 2 μg/g morphine; T 3: 10 μg/g morphine; and T 4: 20 μg/g morphine. Ten replicates of 50 larvae were grown at 22 °C for each treatment and their development was compared at four comparison intervals; CI 1: 4-day-old larvae; CI 2: 7-day-old larvae; CI 3: pupae; and CI 4: adults. Length and width were measured for larvae and pupae, and costae and tibiae were measured for adults. Additionally, day of pupariation, day of adult eclosion, and survivorship were calculated for each replicate. The continued presence of morphine in meat was qualitatively verified using high-performance liquid chromatography with acidic potassium permanganate chemiluminescence detection. Growth rates of C. stygia fed on morphine-spiked mince did not differ significantly from those fed on control mince for any comparison interval or parameter measured. This suggests that C. stygia is a reliable model to use to accurately age a corpse containing morphine at any of the concentrations investigated.

Tolypocladium cylindrosporum, a novel pathogen for sheep blowflies

Dead larvae and pupae of the sheep blowfly, Lucilia sericata, were collected from field soil and subjected to pathological examination. A haemocoel sample of each cadaver was screened for pathogens by growth on specific media, and dominant isolates were characterised with biochemical and morphological tests. Thirty‐eight bacterial and 15 fungal isolates were isolated and bioassayed against L. sericata larvae in soil. Nearly all larvae challenged with microbes survived to emergence of the adult fly, but two Tolypocladium cylindrosporum isolates caused a 100% reduction in emergence. A selected isolate was further tested against larvae of L. sericata, L. cuprina, Calliphora stygia and Chry‐somya rufifacies, and there was strong suppression of adult emergence (0–20% emergence) compared to untreated controls (93–100%).

Experimental studies of blowfly ( Calliphora stygia) longevity: A little dietary fat is beneficial but too much is detrimental

This paper is one in a series of experimental studies on the effects of food composition on aging and longevity, using the golden-haired blowfly Calliphora stygia as the animal model. Here we examine how diet fat content affects blowfly life history traits such as longevity, reproduction, feeding rate, body mass, total fat content and membrane fatty acid composition. The highest median and maximum longevity was observed in blowflies fed on low fat diets, while high-fat diets caused more rapid death of the blowflies. A major result was that blowflies feeding on the lowest fat diet had the highest maximal lifespan demonstrating that low levels of diet fat enhanced blowfly lifespan. Diet also influenced gender-specific mortality rates; females lived longer on a high-fat diet, while males lived longer on a low fat diet. Furthermore, we provide data for and explain how blowfly feeding rates, egg production and male harassment affected blowfly longevity. Our results highlight the need for further studies to understand how dietary fats are metabolised and utilised in the golden-haired blowfly.

Food consumption and individual lifespan of adults of the blowfly, Calliphora stygia: a test of the ‘rate of living’ theory of aging

Following eclosion, adult Calliphora stygia were individually housed (at 22 °C and 73% RH) in 125 ml plastic vials and provided with ad libitum access to either 0.125 or 0.2 M sucrose as a food source and daily food consumption measured throughout their adult life. All blowflies were weighed daily and food consumed is determined by weighing individual food dishes. Blowflies provided with 0.125 M sucrose ( N=59) consumed daily a significantly greater amount of the sucrose solution than those provided with 0.2 M sucrose ( n=55) such that the average rates of sucrose consumption were, respectively, 1.72 and 1.96 mg sucrose day −1. There was no significant difference in the survival curves of the two populations with respective average (±SEM) lifespans being 25.4 (±1.2) and 26.5 (±1.2) days. The respective ranges of individual lifespans were 4–53 and 5–50 days. There was no statistically significant relationship between mass-specific rate of sucrose consumption and lifespan in either population but there were highly significant ( P<0.0001) correlations between lifetime sucrose consumption and lifespan in both groups of blowflies. These findings contradict the predictions of the ‘rate of living’ theory of aging. In both populations of blowflies, body mass and the rate of food consumption were relatively constant through the adult life of blowflies, except that a few days before death both sucrose consumption and body mass showed a dramatic decline.

Video analysis of predation by polyphagous invertebrate predators in the laboratory and field

Abstract This paper describes field and laboratory time-lapse video analyses of the behavioral responses of the groups: Arachnida: Acari, Araneae, and Opiliones; Myriapoda: Chilopoda; Hymenoptera: Formicidae; Crustacea: Isopoda; and Coleoptera: Staphylinidae to live eggs of the brown blowfly, Calliphora stygia F. (Diptera: Calliphoridae), used as factitious prey in two contrasting agricultural field margins and in the laboratory. Field video results showed that predation by mites was greatest in tree-lined boundaries while centipede numbers and activity were greater in post-and-wire boundaries. All except Staphylinidae showed clear diurnal patterns of activity and egg predation rate over the 12 h recording period. Based on the number of eggs removed, number of eggs examined, predator numbers, and predator activity, three indices were formulated that allowed predator groups to be ranked according to their effectiveness as predators. Commensal interactions between the mites and harvestmen, mediated via mite-pierced eggs, were suggested from field data and confirmed in the laboratory. Phalangium opilio preferred to feed on both manually and mite-pierced compared with untreated eggs, but showed a stronger preference for manually pierced ones than mite-pierced, consuming six times as many over the same period. This is the first demonstration of a commensal interaction between two agroecosystem predators. If commensalism is common in agroecosystems it could increase the effectiveness of biological control. It may also need to be incorporated within theoretical models and may complicate the extrapolation of laboratory-based feeding studies to field situations.

The Forensic Application of Allozyme Electrophoresis to the Identification of Blowfly Larvae (Diptera: Calliphoridae) in Southern Australia

Most known carrion-breeding species of blowflies in southern Australia are of the genus Calliphora. The morphological similarity of the immatures of these species means that correctly identifying them poses a challenge for forensic entomologists. This study investigates the potential of allozyme analysis to assist with this task. Molecular profiles of third-instar larvae and adults representing four of these carrion-breeding species, Calliphora stygia, C. dubia, C. hilli hilli, and C. vicina, were compared at 42 allozyme loci. The two life stages were found to display almost identical allozyme profiles in each species (93% of loci were expressed in both life history stages), enabling the reliable identification of larvae in these four species. Integration of these results with data from a previous study indicates that allozyme analysis would also be suitable for rapid, species-level identification of the larvae of six other carrion-breeding Calliphora species occurring in southern Australia. This is the first report of the application of allozyme data to the identification of forensically important blowflies.

Small vertebrate carrion and its use by blowflies (Calliphoridae) causing ovine myiasis (flystrike) in New Zealand

Four species of Calliphoridae that are a primary cause of flystrike (Calliphora stygia; Lucilia sericata; L. cuprina; Chrysomya rufifacies) were bred out from carrion placed in pasture and shelter belt ecotopes. Only two of these species utilised carcases in the shelter belt, compared with all four in the pasture, but productivity was higher in the former. Overall, possum carcases were the most preferred breeding resource followed by magpie and blackbird, with mouse not used.The four primary blowfly species (= strikefly guild) comprised 71.6% of Diptera emerging from possums, 63% from magpies and 27% from blackbirds. Mouse carcases were utilised by other Diptera but not by strikeflies in this study. These results suggest that small animal carrion is an important breeding resource for blowflies that cause ovine myiasis in New Zealand.

Toxicity of green tree frog (Litoria caerulea) skin secretion to the blowflies Calliphora stygia (Fabricius) and Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae)

Many instances of attack by flies (Diptera) upon adult amphibians have been reported. The green tree frog (Litoria caerulea) produces a skin secretion that protects the frog from infection and predation. In this laboratory study, we tested the secretion for its effect on two calliphorids, the Australian sheep blowfly, Lucilia cuprina, and the eastern goldenhaired blowfly, Calliphora stygia, to investigate the role of frog skin secretion in defence against dipteran attack. Topical application to L. cuprina larvae caused mortality, resulting in the eclosion of fewer flies. Direct application upon C. stygia adults caused mortality, whereas introducing the secretion into food caused mortality as well as reduced feeding rates. Results suggest that both physical and chemical properties of the secretion play a role in its toxicity. The skin secretion of L. caerulea may be effective in the defence of this frog against Diptera in general; however, it may have evolved initially in response to attack by particular flies of parasitic genera.

A further modification of the West Australian fly trap for blowfly studies

A cheap and effective modification of the Western Australian blowfly trap is described. The trap, used with a liver and sodium sulphide bait, has proved an efficient means of determining seasonal variations in activity of the principal sheep blowfly strike species Lucilia sericata, L. cuprina, Calliphora stygia and Chrysomya ruffacies in New Zealand.

Habitat preferences and carcase colonization by sheep blowflies in the northern North Island of New Zealand

In urban Auckland, from September 1991 to May 1992, only six specimens of the Australian sheep blowfly, Lucilia cuprina, were collected in farmed parkland and in garden habitats. The common green blowfly, Lucilia sericata, was the most common calliphorid trapped in these habitats. Neither of the two Lucilia species were found in native bush remnants in urban or rural areas where Calliphora hilli was dominant. Similarly very few L.cuprina (0.3% of the total) were trapped in rural rubbish tips in January and February where the majority of blowflies were again L.sericata. These results are compared with data collected from pastoral habitats, where L.cuprina is the major cause of flystrike. Lucilia cuprina was reared from five out of ninety-nine carcases found in rural areas. Calliphora stygia and L.sericata were the most common blowflies colonizing carrion and were reared from 59% and 51% of the carcases respectively.

A study of sheep blowflies at Limestone Downs sheep station in the northern Waikato, New Zealand, over two summers

Abstract Sheep blowflies collected in a baited, wind-orientated trap in the northern Waikato from August 1989 to May 1991 were predominantly the brown blowfly, Calliphora stygia (Fabricius), in the spring and the hairy maggot blowfly, Chrysomya rufifacies (Macquart), in the summer. The common green blowfly, Lucilia sericata (Meigen), and the Australian sheep blowfly, L. cuprina (Wiedemann), represented 15.1 and 2.4% of the total trap catch respectively in 1989/90 and 12.6 and 7.8% respectively in 1990/91. However, significantly more of the two Lucilia spp. and C. stygia were collected when the trap was lowered from 1.5 to 0.65m. In contrast, no L. cuprina was trapped in suburban Auckland in the 1990/91 summer. Of the total daily fly catch, 84% were collected from 1000 to 1500 h.

A model for the aging of fly larvae in forensic entomology

A method is described for determining the time of hatching of blowfly larvae on a corpse with respect to temperature. Temperature is known to have a profound effect on the rate of growth of fly larvae, and it is suggested that past assumptions that the growth of larvae found in a corpse has taken place at one approximated ambient temperature may have led to large overestimates of the development time of the larvae, and thus overestimates of time of death. Larvae of Lucilia cuprina, Calliphora vicina (=erythrocephala), Calliphora stygia and Calliphora hilli were cultured under constant temperatures, and their growth rates modelled with a logistic growth curve. Two programmes have been developed, one to compute the parameters for the logistic equations, the other is used to estimate the time elapsed from the time at which a sample is removed from a body to the estimated hatching time of the larvae comprising the sample, with temperatures and species as variables.

Growth energetics in relation to temperature for larvae of four species of necrophagous flies (Diptera: Calliphoridae)

Abstract The growth characteristics of the larvae of the major members of a necrophagous fly guild in Tasmania (Lucilia cuprina, Calliphora stygia, Calliphora vicina and Calliphora hilli) were measured to assess their competitive ability. The measurements were made at temperatures between 10 and 45°C, to cover the range of temperatures that would be encountered by larvae in carrion or myiasis under field conditions. The characteristics measured were net production and respiration. The indices K2i (instantaneous growth efficiency), K2c (cumulated growth efficiency) and Mi (instantaneous cost of maintenance) were calculated. Generally K2c and K2i are highest and Mi lowest at 25°C for all the species. A sinusoidal response in K2c, K2i and Mi against temperature is seen for L. cuprina, C. stygia and C. vicina. This response is‘cold’adapted in the Calliphora species and‘warm’adapted in L. cuprina.Egg size, egg caloric density and the energy content of the eggs are discussed in relation to the‘fitness’and reproductive strategies of the four species. The thermal tolerance range of L. cuprina determined here suggests that carrion may provide a significant number of this fly particularly in areas where Chrysomya spp. do not occur, and in large carcasses where temperatures are elevated.

Life history responses to larval food shortages in four species of necrophagous flies (Diptera: Calliphoridae)

AbstractThe effects of artificially reduced amounts of larval food on various life history parameters of Lucilia cuprina, Calliphora stygia, C. vicina, and C. hilli were measured to assess the likely reaction of these blowflies to competition in carrion. With increasing food shortage the puparia were reduced by up to 12% of the weight attained under conditions in which food was unlimited. The size of eggs laid by adults which had been subject to food deprivation as larvae was unchanged, but all species showed a reduction in the number of ovarioles. An index of mass‐specific reproductive investment varied considerably between the species, and the relationships between this index and the preferred habitats and dispersal strategies of the species are discussed.

THE SUCCESSION AND RATE OF DEVELOPMENT OF BLOWFLIES IN CARRION IN SOUTHERN QUEENSLAND AND THE APPLICATION OF THESE DATA TO FORENSIC ENTOMOLOGY

AbstractThe succession and rate of development of insects in carrion is potentially a useful and accurate tool for determining the length of time elapsed since death, but the accuracy of this method in Queensland has been severely limited by lack of data. The occurrence of the following species in carrion in the Brisbane district and at a site 450 km west of Brisbane from 1975 to 1979 is discussed: Lucilia cuprina (Wiedemann), Lucilia sericata (Meigen), Calliphora augur (F.), Calliphora stygia (F.), Calliphora hilli (Patton), Chrysomya rufifacies (Macquart), Chrysomya varipes (Macquart), Chrysomya megacephala (F.), Chrysomya nigripes Aubertin, Chrysomya saffranea (Bigot), Hemipyrellia ligurriens Wiedemann, Chrysomya megacephala (F)., Tricholioproctia tryoni (J. and T.), Ophyra spinigera Stein and Australophyra rostrafa (R. ‐D.).Detailed observations at constant temperatures were made on rate of development of flies commonly infesting human cadavers. The duration of the egg, first and second larval instars, total feeding period, total larval period, pupal period and egg to adult period are given for the following species at the temperatures indicated: L. cuprina (15–34°C), C. augur (9–28°C), C. srygia (9–28°C), Ch. rufifcies (20–34°C) and A. rostrara (9–28°C). Limited data on rate of development of Ch. varipes, Ch. sajranea, Ch. nigripes and Ch. megacephala are also included. The application of these data to forensic entomology is discussed.

Circadian clock control of the eclosion rhythm of the brown blowfly,Calliphora stygia(Diptera: Calliphoridae)

In natural conditions the adults of the brown blowfly, Calliphora stygia (Fabricius) emerge from puparia around dawn. In laboratory experiments, under artificial light cycles of 12 h light and 12 h dark (LD 12:12), eclosion occurs at the dark to light transition. The timing of eclosion is controlled by an endogenous circadian clock with a free-running period of 24.4 h at 20°C in constant darkness (DD). The clock is predominantly sensitive to light in the larval stage, but it is sensitive to temperature in both the larval and pupal stages. The adaptive significance of the eclosion rhythm is discussed together with hypotheses concerning the functioning of the eclosion clock during development.