Biodiversity of Forensically Relevant Blowflies (Diptera: Calliphoridae) at the Anthropology Research Facility in Knoxville, Tennessee, USA

Simple Summary

This study investigates the biodiversity and seasonal distribution of blowflies at the Anthropology Research Facility (ARF) of the University of Tennessee, which is also known as the “Body Farm”. Blowflies are among the first insects that access dead bodies, and have a significant impact on the rate and pattern of decomposition. Although the ARF has been used for numerous taphonomic and entomological studies over the past 40 years, it is not yet fully known what blowfly species are present in the area. After a 14-month-long blowfly survey at the ARF, we collected a total of 3180 adult blowflies, comprising 13 species from 7 genera. Phormia regina (Meigen) and Lucilia coeruleiviridis (Macquart) were the predominant species collected from this survey, representing 65.9% and 20.6% of collections, respectively. Among the 13 species, Protophormia terraenovae (Robineau-Desvoidy) was collected for the first time in Tennessee. In addition to relative abundance, we also investigated blowfly community composition, species abundance, richness, and diversity by season. This research is expected to provide researchers at the ARF with accurate information about the blowflies so that they can plan and design their research accordingly.

Abstract

Understanding the biodiversity and distribution of forensically relevant blowflies (Diptera: Calliphoridae) in a region can aid in legal investigations when insects are associated with remains. For this purpose, we conducted a 14-month-long blowfly survey at the Anthropology Research Facility (ARF) of the University of Tennessee in Knoxville, Tennessee. Traps baited with pork kidney were deployed for 24 h twice a month throughout the study. A total of 3180 adult blowflies were collected, comprising 13 species from 7 genera. Phormia regina (Meigen) and Lucilia coeruleiviridis (Macquart) were the predominant species collected from this survey, with collections representing 65.9% and 20.6%of total flies captured, respectively. In addition to relative abundance, we investigated blowfly community composition, species abundance, richness, and diversity by season. One state record was identified, with adult Protophormia terraenovae (Robineau-Desvoidy) being collected for the first time in Tennessee. Additionally, an earlier record of Chrysomya megacephala (Fabricius) in Tennessee was noted. These findings can be used to aid in legal investigations in the area and surrounding areas where work is limited, as well as to provide information on which forensically relevant species should be the subject of future research in the area.

First record of the oriental latrine fly, Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae), in Tennessee, USA

PURPOSE

Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) is a medically and forensically important blow fly species that invaded the United States three decades ago and has continued to expand its distribution across the country ever since. Unlike many other blow fly species, larvae of C. megacephala can develop in feces, particularly from humans. Additionally, C. megacephala is known to carry antibiotic-resistant bacteria in even greater quantities than house flies in tropical areas. This behavior, along with its dissemination into and prevalence within human inhabited environments (e.g., outdoor markets, urban neighborhoods), makes C. megacephala a potential threat to human health. This short communication serves as the first record of C. megacephala in Tennessee, USA.

METHODS

Collections of adult and larval blow flies were made from two sets of human remains decomposing at the Anthropology Research Facility (ARF) at the University of Tennessee. Specimens were confirmed by an expert to be C. megacephala.

RESULTS

A total of seven individual specimens (four adults and three larvae) of C. megacephala were collected from human bodies at the ARF. These results indicate that C. megacephala is not just dispersing into this environment as adults, but actively colonizing human remains in this semi-urban area.

CONCLUSION

These observations support the previously described behavior and habitat of this filth-breeding fly in many Asian countries where it is considered medically and forensically important. Therefore, continuously updated distribution records, like this one, are critical for tracking the movement of C. megacephala across the United States.

Competition Among Three Forensically Important Blow Fly Species (Diptera: Calliphoridae): Phormia regina, Lucilia sericata, and Chrysomya rufifacies

Avoiding competition is thought to explain insect successional patterns on carrion, but few studies have looked at competition directly. We use replacement series experiments with three species of blow flies: Phormia regina (Meigen) (Diptera: Calliphoridae), Lucilia sericata (Meigen) (Diptera:Calliphoridae), and Chrysomya rufifacies (Macquart) (Diptera:Calliphoridae) to characterize competitive relationships. From experimental results, P. regina showed a significant competitive advantage over L. sericata. Infestation of carrion differs between L. sericata and P. regina; specifically, L. sericata oviposits on carrion without any delay, while P. regina typically delays oviposition. Our findings are consistent with the notion that differences in oviposition times represent a mechanism for L. sericata to avoid potential competition. Competition by C. rufifacies differs since C. rufifacies, in the event of a limited food supply, will prey on other maggot species. In replacement series experiments, C. rufifacies killed all P. regina in mixed treatments, representing an ultimate competitive advantage. In the United States, these two species do not often overlap because of differences in seasonal distribution. However, with climate change, phenological separation may grow less distinct. Surprisingly, in replacement series experiments with C. rufifacies and L. sericata, no competitive interactions were observed. In other studies, L. sericata has been shown to form clusters away from predaceous maggots, allowing improved survival, which may account for the absence of predation by C. rufifacies. Finally, this study shows that replacement series models are useful in measuring competition, supporting the notion that interspecific competition between necrophagous insect species may have driven life history traits of those species.

Phenotypic polymorphism of Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) may lead to species misidentification

Species identification is an essential step in the progress and completion of work in several areas of biological knowledge, but it is not a simple process. Due to the close phylogenetic relationship of certain species, morphological characters are not always sufficiently distinguishable. As a result, it is necessary to combine several methods of analysis that contribute to a distinct categorization of taxa. This study aimed to raise diagnostic characters, both morphological and molecular, for the correct identification of species of the genus Chrysomya (Diptera: Calliphoridae) recorded in the New World, which has continuously generated discussion about its taxonomic position over the last century. A clear example of this situation was the first record of Chrysomya rufifacies in Brazilian territory in 2012. However, the morphological polymorphism and genetic variability of Chrysomya albiceps studied here show that both species (C. rufifacies and C. albiceps) share very similar character states, leading to misidentification and subsequent registration error of species present in our territory. This conclusion is demonstrated by the authors, based on a review of the material deposited in major scientific collections in Brazil and subsequent molecular and phylogenetic analysis of these samples. Additionally, we have proposed a new taxonomic key to separate the species of Chrysomya found on the American continent, taking into account a larger number of characters beyond those available in current literature.

Larval Distribution and Behavior of Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) Relative to Other Species on Florida Black Bear (Carnivora: Ursidae) Decomposing Carcasses

Larval interactions of dipteran species, blow flies in particular, were observed and documented daily over time and location on five black bear carcasses in Gainesville, FL, USA, from June 2002 - September 2004. Cochliomyia macellaria (Fabricius) or Chrysomya megacephala (Fabricius) larvae were collected first, after which Chrysomya rufifacies (Macquart) oviposited on the carcasses in multiple locations (i.e., neck, anus, and exposed flesh) not inhabited already by the other blow fly larvae. Within the first week of decomposition, C. rufifacies larvae grew to ≥12 mm, filling the carcasses with thousands of larvae and replacing the other calliphorid larvae either through successful food source competition or by predation. As a result, C. macellaria and C. megacephala were not collected past their third instar feeding stage. The blow fly species, C. megacephala, C. macellaria, Lucilia caeruleiviridis (Macquart), Phormia regina (Meigen), Lucilia sericata (Meigen), and C. rufifacies, completed two developmental cycles in the 88.5-kg carcass. This phenomenon might serve to complicate or prevent the calculation of an accurate postmortem interval.

Cool-weather activity of the forensically important hairy maggot blow fly Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) on carrion in Upstate South Carolina, United States

The hairy maggot blow fly Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) has expanded its range in the United States since its introduction into Texas (ca. 1980) and has been collected in 15 states. We investigated the bionomics of immature and adult C. rufifacies collected from carcasses of a raccoon Procyon lotor (Linnaeus) and white-tailed deer Odocoileus virginianus Zimmerman in Upstate South Carolina during November 2007, and used these insects to estimate the minimum period of insect activity. Puparia of C. rufifacies were collected from deer carrion; 28% were parasitized by Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae). The mean daily ambient temperature during this study was 11.4+/-1.02 degrees C, representing the lowest recorded mean temperature for adult activity of C. rufifacies; adults of C. rufifacies were observed flying among the carcasses at 9.0 degrees C. Although C. rufifacies is considered a warm-weather blow fly, researchers should be aware of its activity at suboptimal conditions, behavior that might aid its expansion into more northern areas.

Interdisciplinary workshop yields new entomological data for forensic sciences: Chrysomya rufifacies (Diptera: Calliphoridae) established in North Carolina

ABSTRACT Workshops are used for educating law enforcement personnel on the application of entomological, anthropological, and botanical techniques to gather forensically important information from a body recovery site. From 8 to 11 June 2004, such a workshop was conducted in the metropolitan area of Charlotte, NC, by the American Academy of Applied Forensics at Central Piedmont Community College. For this workshop, three pig carcasses weighing individually between 40 and 60 kg were placed in the field 4 June, whereas three pigs similar in size were placed in the field 7 June. During the afternoon session on 11 June, workshop participants collected three Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) third instar larvae from a pig carcass placed in the field on 7 June. These data represent the first records of this forensically important insect in North Carolina; furthermore, these data provide evidence of this species expansion into new geographic regions of the United States. This finding is an example of the benefits derived from an experiential and interdisciplinary approach to educating death scene investigators. Learners acquired new knowledge, put it into practice through the "body" recovery exercise, and ultimately contributed to science by way of the discovery and first documentation of a forensically important insect previously not known to inhabit North Carolina.