Sarcosaprophagous Diptera assemblages in natural habitats in central Spain: spatial and seasonal changes in composition

The composition and spatial distribution of sarcosaprophagous Diptera assemblages were studied using carrion‐baited traps along a bioclimatic gradient of natural habitats in central Spain throughout the different seasons during 1 year. Calliphoridae and Muscidae were the most abundant families, accounting for, respectively, 41.9% and 35.1% of all Diptera specimens collected. Other abundant families were Heleomyzidae (8.4%), Sarcophagidae (6.9%) and Piophilidae (5.1%). Fly assemblage compositions differed among bioclimatic levels, with Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) being the dominant species in mesomediterranean habitats, Muscina levida (Harris) (Diptera: Muscidae) the dominant species in supramediterranean habitats, and Prochyliza nigrimana (Meigen) (Diptera: Piophilidae) the dominant species in oromediterranean habitats. Differences in assemblage composition were also found among seasons. Thermophobic species such as Calliphora vicina Robineau‐Desvoidy (Diptera: Calliphoridae) and some species of Heleomyzidae were well represented during autumn, winter and spring in the three bioclimatic levels sampled. By contrast, thermophilic species such as Ch. albiceps and Lucilia sericata (Meigen) (Diptera: Calliphoridae) and most Muscidae and Sarcophagidae species were more abundant during summer and in mesomediterranean habitats located at lower elevations. Knowledge of the preferences of some species for certain habitats may be of ecological and forensic value and may establish a starting point for further research.     

Blowfly succession from possum (Trichosurus vulpecula) carrion in a sheep-farming zone

The significance of brushtail possum, Trichosurus vulpecula Kerr (Diprotodontia: Phalangeridae) carcasses to the succession and production of Diptera species and its relevance to fly strike management in Tasmania, Australia was examined. Calliphora stygia (Fabricius), Lucilia sericata (Meigen) and Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) were found to be the most abundant and Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) always the least abundant (< 1%) of the putative primary fly invading species to emerge. Carcasses that were left for up to 15 days in the field before being exposed to flies for 2 days also acted as breeding sites for large numbers of all primary fly species, with the exception of L. cuprina. Ordination analysis revealed no relationship between possum carcasses according to their length of exposure but did show significant negative associations between the number of putative secondary invaders (Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae), Chrysomya varipes (Macquart) (Diptera: Calliphoridae) and putative tertiary flies (Hydrotaea rostrata Robineau-Desvoidy (Diptera: Muscidae)) to the number of C. vicina or C. stygia to emerge. There was enormous variability in the numbers of secondary/tertiary fly species to emerge from carcasses (0-11 450) that negatively correlated with the proportion of all flies to emerge that were primary, and with the mean size of adult L. sericata. Although carcass temperatures, especially those with a large larval population, were elevated, this did not appear to result in significant pre-adult fly mortality. The most important primary fly strike species L. cuprina was only found in insignificant numbers, whereas three other members of the fly strike fauna C. stygia, L. sericata and Ch. rufifacies did use possum carrion as an important breeding resource, but left implications for fly strike management inconclusive.     

Temperature‐dependant development of Nasonia vitripennis on five forensically important carrion fly species

The effects of temperature and host species on the development of Nasonia vitripennis Walker (Hymenoptera: Pteromalidae), a forensically important parasitoid of carrion flies, were studied under laboratory conditions. Development time of N. vitripennis on five species of Calliphoridae (Diptera), Calliphora albifrontalis Malloch, Calliphora dubia Macquart, Lucilia sericata Meigen, Chrysomya rufifacies Macquart, and Chrysomya megacephala Fabricius, were determined under eight constant temperatures (15, 18, 21, 24, 27, 30, 33, and 36 °C). Thermal requirements for development (developmental thresholds, thermal constant, and optimum temperature) of N. vitripennis in each host species were estimated using linear and nonlinear models. Upper and lower developmental thresholds ranged between 36.6–38.4 and 9.6–11.1 °C, respectively. The optimum temperature for development was estimated at between 30.6 and 31.8 °C. Statistical differences in the development time of N. vitripennis on the various calliphorid host species were evident within all temperature treatments, particularly at the upper and lower temperature range investigated. As such, it is recommended that insect‐based estimates of time since death in forensic investigations relying on parasitoid evidence should use host‐specific development data where available.     

Annual and spatial activity of dung flies and carrion in a Mediterranean holm-oak pasture ecosystem

The annual activity and spatial distribution of Muscidae and Calliphoridae were investigated in a holm-oak ('dehesa') ecosystem in western Spain over two years in pasture and woodland habitats, using wind-orientated traps baited with a mixture of fresh cattle faeces, liver and sodium sulphide solution. Lucilia sericata (Meigen) was always the dominant species and, with Chrysomya albiceps (Weidemann), Hydrotaea ignava (Harris), Muscina levida (Harris) and Muscina prolapsa (Harris), was more abundant during the second than the first year. By contrast, Calliphora vicina Robineau-Desvoidy, Calliphora vomitoria (L.), Hydrotaea armipes (Fallén), Hydrotaea penicillata (Rondani) and Hydrotaea dentipes (Fabricius) were more numerous during the first than the second year of the study. In summer, the Diptera sampled were significantly more abundant in a wooded than a pasture area. However, in autumn, while H. penicillata remained significantly more abundant in woodland, L. sericata became more abundant in the pasture, whereas C. vicina was captured in open and wooded areas in similar proportions. During winter and spring the populations sampled were relatively small. The changing patterns of abundance are discussed in relation to differences in climate within and between years.     

Blowflies (Diptera: Calliphoridae) activity in sun exposed and shaded carrion in Portugal

The first forensic entomological study performed in Portugal is presented. Two piglet (Sus scrofa L.) carcasses were used to determine adult Calliphoridae activity on carrion over a period of 121 days, all along the end of spring and the summer, both in a shaded and a sunny site. Five decomposition stages were observed and a total of 10723 adult Calliphoridae, belonging to 11 species, were collected. Calliphora vicina, Calliphora vomitoria, Chrysomya albiceps and Lucilia caesar were the dominant species in this study. Decomposition was faster on the carcass exposed to the sun and the number of Calliphoridae specimens was higher there than in the shaded site. It was found a significant effect of the decomposition stage in the number of specimens attracted to the carcass, as well as a significant effect of the interaction between the decomposition stage and insolation regime. Calliphora and Lucilia species did not show preference for sunny or shaded areas. Important differences in the Calliphoridae community structure were found compared to other regions of the Iberian Peninsula, reinforcing the need of further studies in different environments and regions of this geographical area in order to collect information about the local necrophagous fauna used in forensic practice.     

Cuticle hydrolysis in four medically important fly species by enzymes of the entomopathogenic fungus Conidiobolus coronatus

Entomopathogenic fungi infect insects via penetration through the cuticle, which varies remarkably in chemical composition across species and life stages. Fungal infection involves the production of enzymes that hydrolyse cuticular proteins, chitin and lipids. Host specificity is associated with fungus–cuticle interactions related to substrate utilization and resistance to host‐specific inhibitors. The soil fungus Conidiobolus coronatus (Constantin) (Entomophthorales: Ancylistaceae) shows virulence against susceptible species. The larvae and pupae of Calliphora vicina (Robineau‐Desvoidy) (Diptera: Calliphoridae), Calliphora vomitoria (Linnaeus), Lucilia sericata (Meigen) (Diptera: Calliphoridae) and Musca domestica (Linnaeus) (Diptera: Muscidae) are resistant, but adults exposed to C. coronatus quickly perish. Fungus was cultivated for 3 weeks in a minimal medium. Cell‐free filtrate, for which activity of elastase, N‐acetylglucosaminidase, chitobiosidase and lipase was determined, was used for in vitro hydrolysis of the cuticle from larvae, puparia and adults. Amounts of amino acids, N‐glucosamine and fatty acids released were measured after 8 h of incubation. The effectiveness of fungal enzymes was correlated with concentrations of compounds detected in the cuticles of tested insects. Positive correlations suggest compounds used by the fungus as nutrients, whereas negative correlations may indicate compounds responsible for insect resistance. Adult deaths result from the ingestion of conidia or fungal excretions.     

Diptera as vectors of mycobacterial infections in cattle and pigs

Mycobacteria were isolated from 14 (4.5%) of 314 samples, containing 7791 adult Diptera, which were collected in the Czech Republic and Slovakia in 1997-2000. These flies were collected from three cattle herds with paratuberculosis, two pig herds with mycobacterial infections and one farm that kept both cattle and pigs and that did not have problems of mycobacterial infections. Mycobacterium intracellulare was isolated from Eristalis tenax Linnaeus (Diptera: Syrphidae) captured from a pig herd. Mycobacterium avium ssp. avium (serotype 8) was isolated from flies of the genera Drosophila Fallen (Diptera: Drosophilidae) and Musca Linnaeus (Diptera: Muscidae) originating from a pig herd. Mycobacterium spp. were isolated from Musca spp. and Mycobacterium fortuitum was isolated from dung flies of the genus Scatophaga Meigen (Diptera: Scatophagidae), Musca spp. and Stomoxys calcitrans Linnaeus (Diptera: Muscidae) captured in the same herd. Mycobacterium scrofulaceum was isolated from S. calcitrans from the farm with both cattle and pigs. Mycobacterium avium ssp. paratuberculosis was isolated from Scatophaga spp. collected from pastures grazed by one of the cattle herds and from Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) and Lucilia caesar Linnaeus (Diptera: Calliphoridae) captured in a slaughterhouse, where cattle infected with paratuberculosis were slaughtered. Mycobacterium phlei was isolated from flies of the genus Lucilia captured at a waste bin. These data indicate that mycobacteria may be spread by adult flies that have been in contact with material contaminated with these pathogens.     

A checklist of arthropods associated with pig carrion and human corpses in southeastern brazil

Necrophagous insects, mainly Diptera and Coleoptera, are attracted to specific stages of carcass decomposition, in a process of faunistic succession. They are very important in estimating the postmortem interval, the time interval between the death and the discovery of the body. In studies done with pig carcasses exposed to natural conditions in an urban forest (Santa Genebra Reservation), located in Campinas, State of S?o Paulo, southeastern Brazil, 4 out of 36 families of insects collected - Calliphoridae, Sarcophagidae, Muscidae (Diptera) and Dermestidae (Coleoptera) - were considered of forensic importance, because several species were collected in large numbers both visiting and breeding in pig carcasses. Several species were also observed and collected on human corpses at the Institute of Legal Medicine. The species belonged to 17 different families, 6 being of forensic importance because they were reared from human corpses or pig carcasses: Calliphoridae, Sarcophagidae, Muscidae, Piophilidae (Diptera), Dermestidae, Silphidae and Cleridae (Coleoptera). The most important species were: Diptera - Chrysomya albiceps, Chrysomya putoria, Hemilucilia segmentaria, Hemilucilia semidiaphana (Calliphoridae), Pattonella intermutans (Sarcophagidae), Ophyra chalcogaster (Muscidae), Piophila casei (Piophilidae); Coleoptera - Dermestes maculatus (Dermestidae), Oxyletrum disciolle (Silphidae) and Necrobia rufipes (Cleridae).     

Bimodal cue complex signifies suitable oviposition sites to gravid females of the common green bottle fly

Gravid females of the common green bottle fly, Lucilia sericata Meigen (Diptera: Calliphoridae), readily locate recently deceased vertebrates as oviposition sites, particularly when these animals have been injured. We investigated semiochemical and visual cues that mediate attraction of gravid females to fresh rat carrion. Female flies were more strongly attracted to incised rat carrion than to intact carrion. They were also attracted to Porapak Q headspace volatile (HSV) extract of incised rat carrion. Analyzing aliquots of Porapak Q HSV extract by gas chromatographic‐electroantennographic detection revealed nine components [phenol, para‐ and/or meta‐cresol (could not be separated), guaiacol, dimethyl trisulfide (DMTS), phenylacetaldehyde, (E)‐2‐octenal, nonanal, and tetramethyl pyrazine] that consistently elicited responses from blow fly antennae. In laboratory experiments, a synthetic blend of these nine components was as attractive to gravid females as Porapak Q HSV extract, but blend attractiveness was due entirely to DMTS. In both laboratory and field experiments, increasing doses of DMTS attracted increasingly more flies. Coupled with DMTS, carrion‐type color cues (dark red, black) were more effective than bright color cues (white, yellow) in attracting flies. In field experiments, dark traps baited with DMTS captured a total of 214 calliphorid flies (200 L. sericata, 10 Lucilia illustris Meigen, three Calliphora vicina Robineau‐Desvoidy, one Calliphora vomitoria L.), all of which were gravid females. These results support the conclusion that DMTS and dark color represent a bimodal cue complex that signifies suitable oviposition sites to gravid calliphorid females, particularly L. sericata.     

Oviposition preferences and antennal size in carrion flies

Carrion-feeding flies use odours emanating from the decomposing corpse as cues for oviposition and are described as generalists because the larvae feed on the corpses of diverse species. Whereas several features of the corpse may influence the oviposition choices of these flies, it is not known whether there is a preference for a particular species of corpse. We provided carrion flies with ovipositional (and feeding) choices in a field experiment, in which various odour sources were presented simultaneously. We found novel evidence of broadly consistent choices of carrion by flies from four families. Traps baited with decaying fish flesh captured the greatest number of individuals, whereas traps baited with decaying pig liver typically attracted the least. We also asked whether individuals captured in the various baits vary in antennal size, perhaps reflecting different capacities for odour detection. There was a trend for individuals of Lucilia sericata Meigen (Diptera: Calliphoridae) and the platystomatid collected from the traps baited with pig liver to have significantly larger antennae, whereas individuals of Muscina stabulans (Fallen) (Diptera: Muscidae) captured in traps baited with marine fish flesh had relatively longer antennae for their body size. Our data reveal a more nuanced pattern of oviposition behaviour in these generalist carrion flies, which may reflect differences in their preference of carrion with different nutrients, and in their capacity to detect particular odours.     

Diversity and Synanthropy of Calliphoridae (Diptera) in the Region of Rio Claro, SP, Brazil

Dipteran blowflies (Calliphoridae) are of great medical and hygienic importance as vectors of pathogens and as parasites of living and dead tissue, and their association with carrion allows their use in forensic entomology. The objective of this study was to determine the synanthropic index of adult Calliphoridae (Diptera) collected in Rio Claro, S?o Paulo. Sampling occurred between September 2009 and August 2010. Traps baited with sardines, beef liver, and minced meat were assessed for five consecutive days per month in three distinct ecological areas representing urban, rural, and forest environments. The most abundant species was Lucilia eximia (Wiedemann), followed by Chrysomya albiceps (Wiedemann) and Chrysomya megacephala (Fabricius). Lucilia eximia was the only species present in all seasons and the only species collected during the winter. The season with the lowest abundance was winter, with 69 (5.5%) specimens, and spring was the season with the greatest number of specimens collected (774?C61.8%). The only species found outside inhabited areas (synanthropic) was Lucilia cuprina (Wiedemann), with a synanthropy index (SI) value of +5.7. The SI values for the other species were negative, showing a preference for uninhabited areas. The rural and urban areas were most similar in terms of species composition as were the beef and sardine baits. Among the baits used, liver attracted the greatest abundance of calliphorids, whereas minced meat attracted the greatest diversity.     

Diptera of forensic importance in the Iberian Peninsula: larval identification key

A revision of the species and families of sarcosaprophagous flies (Diptera: Calliphoridae, Sarcophagidae, Muscidae, Fanniidae, Drosophilidae, Phoridae, Piophilidae and Stratiomyidae) suitable for forensic purposes in the Iberian Peninsula is presented. Morphological characteristics that allow the accurate identification of third instars of the species present in the Iberian Peninsula are described and presented in the form of a diagnostic key. For larval Calliphoridae, characteristics such as the spines of the body segments were useful for the genus Calliphora whereas features of the anal segment and the cephalopharyngeal skeleton were useful for larvae of Lucilia. Identification of three Chrysominae species present in the Iberian Peninsula is included. For larval Sarcophagidae, characters such as the arrangement and shape of spiracular openings, structures of the anal segment and the cephalopharyngeal skeleton were used for the first time. A new record of Sarcophaga cultellata Pandellé, from a human corpse, is also included as well as recent incursions into the European cadaveric entomofauna such as Synthesiomyia nudiseta (van der Wulp) and Hermetia illucens (Linnaeus). This work provides useful new information that could be applied to forensic investigations in the Iberian Peninsula and in southern Europe.     

Spatial and temporal habitat partitioning by calliphorid blowflies

Calliphorid blowflies perform an essential ecosystem service in the consumption, recycling and dispersion of carrion nutrients and are considered amongst the most important functional groups in an ecosystem. Some species are of economic importance as facultative agents of livestock myiasis. The interspecific ecological differences that facilitate coexistence within the blowfly community are not fully understood. The aim of this work was to quantify differences in habitat use by calliphorid species. Thirty traps were distributed among three habitats at two sites in southwest England for collections made during March–August 2016. A total of 17 246 specimens were caught, of which 2427 were Lucilia sericata, 51 Lucilia richardsi, 6580 Lucilia caesar, 307 Lucilia ampullacea, 4881 Calliphora vicina and 2959 Calliphora vomitoria (all: Diptera: Calliphoridae). Lucilia sericata was the dominant species in open habitats, whereas L. caesar was the most abundant species in shaded habitats. Calliphora specimens were more abundant in the cooler months. These findings suggest that Calliphora and Lucilia species show strong temporal segregation mediated by temperature, and that species of the genus Lucilia show differences in the use of habitats that are likely to be driven by differences in humidity tolerance and light intensity. These factors in combination result in effective niche partitioning.     

New piophilid in town: the first Palaearctic record of Piophila megastigmata and its coexistence with Piophila casei in central Spain

The genus Piophila Fallén (Diptera: Piophilidae) is known from only two species: Piophila casei (L.) is a major pest, a cosmopolitan species and is commonly used as a forensic indicator, whereas Piophila megastigmata McAlpine has until now only been recorded in a natural environment in South Africa. The present work reports the first occurrence of P. megastigmata in the Palaearctic region from specimens collected by carrion‐baited traps throughout different natural habitats of central Spain. Furthermore, the species was also collected with P. casei on corpses of domestic pigs used in a carrion succession study in a periurban habitat in central Spain. Both species occurred on carrion in different seasons, but P. megastigmata was more abundant than P. casei in autumn, arriving earlier at the carcasses and persisting for a longer period. The contrary pattern was observed in spring. The presence of P. megastigmata in different localities in central Spain and its coexistence with P. casei in a periurban habitat make it a potentially useful new tool for legal medicine in Europe; thus this species must be considered in forensic entomology studies.     

Spatial and temporal variability of necrophagous Diptera from urban to rural areas

The spatio-temporal variability of necrophagous fly assemblages in a linear series of habitats from central London to the rural surroundings in the south-west was studied using bottle traps between June 2001 and September 2002. A total of 3,314 individuals in 20 dipteran families were identified from 127 sampling occasions. Calliphoridae accounted for 78.6% of all the dipteran specimens, with Calliphora vicina Robineau-Desvoidy, being the most abundant species (2,603 individuals, 46.9%). Using canonical correspondence analyses (CCA) on 72 fly taxa, six sampled sites and 36 environmental variables, three habitat types corresponding to three groups of flies were identified. These were an urban habitat characterized by C. vicina, Lucilia illustris (Meigen) and L. sericata (Meigen), a rural grassland habitat, characterized by L. caesar (Linnaeus) and a rural woodland habitat characterized by Calliphora vomitoria (Linnaeus), Phaonia subventa (Harris), Neuroctena anilis (Fallén) and Tephrochlamys flavipes (Zetterstedt). Intermediate species (L. ampullacea Villeneuve and P. pallida (Fabricius), located between the three habitats, were also found. Temporal abundance of the 10 most abundant species showed fluctuations between seasons, having low numbers of captured individuals during winter. Correspondence analysis showed clearly seasonal patterns at Box Hill site. The species-habitat associations suggest habitat differentiation between necrophagous guilds in this area and may be of ecological value.     

Synomones in necrophagous larvae of the blow flies Lucilia sericata and Calliphora vomitoria

Chemical signals are widespread in insects, but those resulting in interspecific communication (i.e., synomones) remain understudied. Here, we analysed chemicals left on substrates by two species of blow fly larvae, Lucilia sericata (Meigen) and Calliphora vomitoria (Linneaus) (Diptera: Calliphoridae), which can aggregate together on carrion. Using solid-phase microextraction and dynamic headspace analysis, we identified six compounds common to both species: the decanoic, tetradecanoic, pentadecanoic, hexadecanoic and octadecanoic acids, and the 2-ethylhexyl salicylate. We then tested the behavioural effects of the decanoic and pentadecanoic acids using binary-choice experiments, along with the (Z)-9-tricosene, a pheromone found in many arthropods. The time spent by a larva and its average crawling speed were measured in two sides of an arena, where only one contained a compound at 0.25 or 25 μg/μl. No effect was observed when testing the decanoic acid. The pentadecanoic acid only reduced the speed of C. vomitoria larvae at 25 μg/μl. Finally, L. sericata larvae spent less time in the side containing the (Z)-9-tricosene at 0.25 μg/μl, whereas C. vomitoria spent more time and crawled faster in this side at 25 μg/μl. Although these results did not directly evidence synomones, they suggest that the (Z)-9-tricosene could regulate larval aggregations on carrion.     

Analysis of insects colonised on human corpses during autopsy in Riyadh,Saudi Arabia

In medicolegal cases, an analysis of the presence of insects on human bodies may have potential legal significance. This study investigates the presence of insects on human bodies during autopsies in legal medicine. It was implemented in Riyadh, Saudi Arabia. Nine cadavers were examined, respectively, from four cases of homicide, two cases of burning, one suicide, one accident and one case of neglect. Insects associated with the human corpses were carefully collected and identified using valid taxonomic keys. Three of the cadavers were of children with ages ranging from seven months to nine years. In seven cases decomposition had occurred outdoors while in two cases it was indoors. Overall, eleven different species of insects were identified. Six of the cases exhibited species from five families within Diptera (Calliphoridae, Muscidae, Ulidiidae, Tachinidae and Sarcophagidae), specifically Chrysomya albiceps (Wiedemann), Musca domestica (Linnaeus), Tachinidae sp. (Bigot), Physiphora alceae (Preyssler) and Sarcophaga dux (Thompson). Six of the cadavers hosted beetles, which were identified as Dermestes maculatus (DeGeer), D. frischii (Kugelann), Necrobia rufipes (Fabricius), Nitidula bipunctata (Linnaeus), Pimelia interjecta (Solier) and Latridiidae sp. (Erichson). Moreover, the suicide corpse was colonised by more fly species than the other corpses, while the beetles colonised the homicide and accident corpses more than the other corpses. Analysis of the diversity of insects on human corpses may lead to advances in the understanding of forensic entomology and more sophisticated estimates of the minimum post‐mortem interval.     

The distribution of adult blow-flies (Diptera: Calliphoridae) along an altitudinal gradient in Central Spain

The distribution of Calliphoridae along an altitudinal gradient was investigated in Central Spain using carrion-baited traps. Significant differences were found between elevation and mean abundances of almost all species of blow-flies. Several species of flies could be grouped according to their altitudinal preferences so that samples at high elevations are defined by Calliphora vomitoria and Calliphora vicina while samples at low elevations are defined by two thermophilous species: Lucilia sericata and Chrysomya albiceps. The remaining species show preferences for mid-elevations where wooded areas are more characteristic along the altitudinal gradient. Calliphora vomitoria and Chrysomya albiceps are the most abundant species representing the 87.74 % of all captures. Both species are spatially segregated along the altitudinal gradient. The changing patterns of abundance are discussed in relation to differences in climate conditions along the altitudinal gradient concluding that the environmental variables that influence the seasonality of many species also play an important role to explain the spatial distribution.