A preliminary study of insect fauna on pig carcasses located in sugarcane in winter in southeastern Brazil

Dipterofauna Associated With Rat Carcasses in the Atlantic Forest, Southeastern Brazil

Each biome has its own fauna and intrinsic local conditions that determine the succession patterns of insects on carcasses. For this reason, regional studies are very important to forensics. This study deals with the flies that visit carcasses of Rattus rattus (L., 1758) in the Atlantic Forest remnant of Floresta da Tijuca, Rio de Janeiro, Brazil. We compare the diversity and relative abundance of fly families and species throughout the four seasons of the year and test for correlations between certain environmental variables and fly richness. In each of the four seasons, we exposed the carcasses of three rats. The carcasses were put in traps that were installed on the ground, separated by 100 m. The flies were collected from the carcasses on a daily basis, and were taken to the laboratory and kept in a climate chamber (28 °C day and 26 °C night). A total of 5,537 flies were captured, identified into 12 families: Calliphoridae (4,884 specimens), followed by Sarcophagidae, Micropezidae, Fannidae, Muscidae, Phoridae, and Neridae. Canonical correspondence and redundancy analyses of the environmental variables indicated no relationship between the seasons and fly abundance. Carcass decomposition lasted longer in the winter (12 d) than in the summer (8 d). The Margalef richness index indicated higher richness in the spring and winter, and lower richness in the summer. The Shannon-Wiener index and Simpson dominance indicated greater diversity in the spring. Diptera colonized all stages of decomposition. The families Calliphoridae and Sarcophagidae were more prevalent during the Fermentation stage. Our data have important implications for forensic entomology.

Unusual presence of Ornidia robusta (Diptera: Syrphidae) causing pig myiasis in Argentina

Myiasis is caused by dipterous larvae from the Calliphoridae, Sarcophagidae, Muscidae, Cuterebridae, and Syrphidae families. In this work, Cochliomyia hominivorax, Chrysomya megacephala, and Ornidia robusta were identified causing vulva, ear, and leg myiasis in pigs in Tucuman province, northwestern Argentina. The report of the presence of C. hominivorax and C. megacephala is very important due to their role as myiasis-causing and disease vectors. The occurrence of Ornidia robusta is remarkable, since it constitutes the first record of myiasis in general and of myiasis in pigs in particular. Lastly, the presence of Sarcophaga spp. is also interesting, since some of them originate myiasis and are therefore of concern for cattle, wild animals, and human populations.

Blowflies (Diptera, Calliphoridae) Associated with Pig Carcasses in a Caatinga Area, Northeastern Brazil

Studies that focused on Calliphoridae associated with pig carcasses are abundant in southern and southeastern Brazil; however, there are few in northeast. Here, we present an inventory of the blowfly species associated with the stages of decomposition of pig carcasses in a caatinga area during dry and rainy seasons. The study took place at the Private Reserve for the Environmental Inheritance "Fazenda Almas," state of Paraíba, Brazil. Using a modified version of the Shannon trap, 32,909 adult specimens belonging to eight species were captured. During the dry season, Cochliomyia macellaria (Fabricius) (52.2%) and Chrysomya albiceps (Wiedemann) (39.9%) were the most abundant species. In the rainy season, when the majority of individuals were captured (93.7%), Chloroprocta idioidea (Robineau-Desvoidy) (71.1%) was the most abundant. Five decomposition stages were recognized, being the active decay the most attractive to colonization by blowflies, except for Lucilia eximia (Wiedemann), which was more abundant in the bloated stage.

Insects breeding in pig carrion in two environments of a rural area of the state of minas gerais, Brazil

The main objective of this study was to identify potential forensic indicators in the insect fauna associated with pig carrion and the pattern of insect succession during the decomposition process in two environments of a rural area in Uberlândia, State of Minas Gerais, Brazil. The study was conducted at two locations: in a pasture and in a fragment of a semi-deciduous forest (vegetation profile of the Cerrado biome) in two different seasons (rainy and dry) of 2010. The decomposition process was more rapid in the rainy season. More than 32,000 insects belonging to 17 species of 6 families of Diptera and 2 species of Coleoptera bred in the carcasses. The majority of Diptera bred in the first three stages of decomposition. However, Phoridae and Coleoptera bred mainly in the last two stages. The insects bred more abundantly in the pasture and in the humid season. The exceptions were the Fanniidae (Diptera), which bred more abundantly in the forest and the Dermestidae and Cleridae (Coleoptera), which did not demonstrate any preference in terms of environments and were more abundant in the dry season, respectively. Species such as Chrysomya albiceps (Wiedemann), Peckia (Patonella) intermutans (Walker), Necrobia rufipes (De Geer), and Dermestes maculatus (De Geer) may be potential indicators of post-mortem interval. Hemilucilia segmentaria (Fabricius) and Ophyra aenescens (Wiedemann) may be indicators of localization of the natural environment, while Musca domestica Linnaeus may be an indicator of the anthropic environment. The study thus presented many species of potential forensic indicators in rural areas of this region.

How photoperiods affect the immature development of forensically important blowfly species Chrysomya albiceps (Calliphoridae)

The purpose of this study was to verify the influence of different photoperiods on larval body weight, post-embryonic development, and viability of Chrysomya albiceps. The bioassays were performed in acclimatized chamber at 27 ± 1 °C and 60 ± 10 % relative humidity regulated by three different light and dark cycles for a period of 24 h-12:12, 24:00, and 00:24. Four replications with 50 newly hatched larvae each were used per photoperiod. The larvae were placed in container containing bovine ground meat (50 g). When mature larvae spontaneously abandoned the diet, they were individually weighed and separated into glass tubes until emergence. The larvae that did not abandon the diet were not weighed. The larvae from 24 h of photophase did not abandon the diet and pupated inside, so these larvae were not weighed and the larval and pupal developments were not registered. The mean of larval body weight did not vary between the 24 h scotophase and 12 h photophase. The mean duration of larval developmental time varied significantly when comparing the 24 h scotophase and the 12 h photophase, and the pupal developmental time also varied for the same photoperiods; in both stages, the duration of development was faster in the 24 h scotophase. The developmental time of neo-larvae to adult was verified in all photoperiods and gradually increased as photophase increased. There was a trend to augment of viability with the reduction of photophase length.

Preliminary study of the succession pattern of necrobiont insects, colonising species and larvae on pig carcasses in Temuco (Chile) for forensic applications

Knowledge regarding the succession patterns of insects that visit carcasses as well as the other arthropod that colonise them and analysis of the parameters that are associated with larvae allow calculation of the minimum postmortem interval (PMI). This information is obtained from experiments carried out under specific geoclimatic conditions, which determine their application in forensic environments under similar conditions. The field study presented here is the first in Chile to analyse the decomposition process of pig carcasses and the associated succession of insects, colonising species and parameters related to larval masses. All of the larvae obtained from daily samples were measured (in mm), and their mean, range, standard deviation and stage of development (instars) were determined. The carcasses reached the dry remains stage in only 11 days. Seven species of Diptera visited the carcass during the process, but only two species colonised it by means of egg deposition followed by development of larvae: Cochliomyia macellaria (Fabricius) and Lucilia sericata (Meigen) (Diptera: Calliphoridae), which exhibited a duration of the development cycle from egg to adult of 21 days. The collected Coleoptera correspond to five predator species (Staphilinidae and Histeridae). From the results of this study, it can be concluded that only some of the insect species present in this region can provide information that can be used in forensic entomology and that analysis of larval masses of colonising species can be a valuable tool for determining the PMI(min) in this region of Chile.

Succession of carrion fauna in the arid region of San Juan Province, Argentina and its forensic relevance

The succession of carrion fauna and the decomposition stages were studied in the arid environment of San Juan Province, Argentina (31°32'34.7″ S; 68°34'39.4″ W). Two pig carcasses (Sus scrofa) were placed in wire mesh cages, 100 m apart from each other. Each carcass was surrounded by pitfall traps, and a modified Malaise trap was placed above. Daily samplings were carried out to collect the insects present in the carcasses and the traps, and body and environmental temperature were measured. The main colonizer species was Chrysomya albiceps (Wiedemann) and its larvae were dominant over other Diptera. The first adult blowflies emerged at 8.9 days. The time to reach the remains stage was 8 days shorter than for other South American sites. We recorded the early arrival of adult Dermestes maculates De Geer and Dermestes ater De Geer 2 days after the beginning of the assay, and larvae of these species were recorded 4 days after. We determined a 1.5-day error in the postmortem interval estimation using the temperatures measured in the assay and those recorded by the nearest meteorological station.