M. J. R. Hall

Best practice in forensic entomology—standards and guidelines

Forensic entomology, the use of insects and other arthropods in forensic investigations, is becoming increasingly more important in such investigations. To ensure its optimal use by a diverse group of professionals including pathologists, entomologists and police officers, a common frame of guidelines and standards is essential. Therefore, the European Association for Forensic Entomology has developed a protocol document for best practice in forensic entomology, which includes an overview of equipment used for collection of entomological evidence and a detailed description of the methods applied. Together with the definitions of key terms and a short introduction to the most important methods for the estimation of the minimum postmortem interval, the present paper aims to encourage a high level of competency in the field of forensic entomology.

Myiasis of Humans and Domestic Animals

Publisher Summary This chapter focuses on the myiasis of humans and domestic animals. Myiasis is the infestation of live human and vertebrate animals with dipterous larvae, which, at least for a certain period, feed on the hosts dead or living tissue, liquid body substances, or ingested food. Myiasis is a large field with publications in many widely dispersed areas of the literature. Myiasis has a greater economic impact as an infestation of animals than of humans; there are no species of Diptera which are restricted to humans for their development but there are many that have a very restricted host range on animals. The different forms of myiasis have been classified in two ways. First, in anatomical terms, based on the part of the hosts body that is infested and second, in parasitological terms, according to the types of host–parasite relationship. Myiasis from a range of species produces an immunological response in the host. There are three levels at which control of myiasis species can be considered: (1) suppression or eradication of fly population (for example, eradication of Cochliomyia hominivorax and Hypoderma species); (2). avoidance of infestation where adult control is not possible (for example, by fly screening, dressing of wounds, prophylactic treatments); and (3) treatment because of failure of both above levels(removal of larvae manually or by insecticides, application of antibiotics). Analytical studies of myiasis have increased dramatically, particularly in alliance with new control and monitoring methods that demand an increased understanding of the biology, physiology, and ecology of the parasites, for example, serodiagnosis, vaccine research and trapping.

Forensic entomology: applications and limitations.

Forensic entomology is the science of collecting and analysing insect evidence to aid in forensic investigations. Its main application is in the determination of the minimum time since death in cases of suspicious death, either by estimating the age of the oldest necrophagous insects that developed on the corpse, or by analysing the insect species composition on the corpse. In addition, toxicological and molecular examinations of these insects may help reveal the cause of death or even the identity of a victim, by associating a larva with its last meal, for example, in cases where insect evidence is left at a scene after human remains have been deliberately removed. Some fly species can develop not only on corpses but on living bodies too, causing myiasis. Analysis of larvae in such cases can demonstrate the period of neglect of humans or animals. Without the appropriate professional collection of insect evidence, an accurate and convincing presentation of such evidence in court will be hampered or even impossible. The present paper describes the principles and methods of forensic entomology and the optimal techniques for collecting insect evidence.

Larval growth rates of the blowfly, Calliphora vicina, over a range of temperatures

Abstract.  Blowfly larvae (Diptera: Calliphoridae) fulfil an important ecological function in the decomposition of animal remains. They are also used extensively in forensic entomology, predominantly to establish a minimum time since death, or a minimum post‐mortem interval, using the larval length as a ‘biological clock’. This study examined the larval growth rate of a forensically important fly species, Calliphora vicina Robineau‐Desvoidy (Diptera: Calliphoridae) at temperatures of between 4°C and 30°C, under controlled laboratory conditions. The laboratory flies had been trapped initially in London, U.K. The minimum developmental temperature was estimated to be 1°C and 4700 accumulated degree hours (ADH) were required for development from egg hatch to the point of pupariation. Lines fitted to the laboratory larval growth data were found to adequately explain the growth of larvae in the field. The nature of variation in growth rates from geographically isolated populations is discussed.

The New World screwworm fly in Libya: a review of its introduction and eradication.

Abstract. The New World screwworm fly, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), became established in the Old World for the first time during 1988, in the Socialist Peoples Libyan Arab Jamahiriya. An obligate parasite of mammals in its larval stages, causing wound myiasis, it is one of the most serious insect pests of livestock in the Americas. To avert a major disaster for the livestock industry and wildlife of Africa and southern Europe, the Libyan Government and the Food and Agriculture Organization of the United Nations launched a massive screwworm eradication programme, based on the sterile insect technique, SIT. An initial containment operation involved veterinary teams working in the infested area (25,000km2 around Tripoli), regularly inspecting livestock and, if necessary, treating them with insecticide. Quarantine stations were also set up, to prevent the movement of infested livestock out of the area. Sterile flies from the Mexican‐American Commission for Eradication of Screwworms were first released in December 1990 at the rate of 3.5 million per week. This built up to 40 million per week by May 1991. The release of sterile flies was terminated on 17 October 1991, 6 months after the last detected case of screwworm myiasis in Libya. Intensive surveillance and quarantine activities will, however, continue through 1992. During 1992 the Libyan Government should be able to officially declare the New World screwworm eradicated from Libya, making it one of the most important success stories of pest control.

The oestrid flies: biology, host-parasite relationships, impact and management.

Introduction, D D Colwell, M J R Hall and P J Scholl Historical Perspectives on the Importance and Impact of Oestrids, R A Roncalli, Milltown, USA Phylogeny and Evolution of the Bot Flies, T Pape, Zoological Museum, Copenhagen, Denmark Molecular Phylogeny and Identification, D Otranto, University of Bari, Italy and J R Stevens, University of Exeter, UK Life Cycle Strategles, D D Colwell Morphology of Adult Oestridae, D M Wood, Agriculture and Agri-Food Canada Egg Morphology, D D Colwell Larval Morphology, D D Colwell Pupal Biology and Metamorphosis Behaviour, A C Nilssen, Tromso Museum, Norway Adult Biology, J R Anderson, Bend, USA Larval - Host Parasite Relationships, C Boulard, INRA, France, E Lello, Botucatu, Brazil, D Colwell and P Dorchies, Ecole Nationale Veterinaire de Toulouse, France Oestrid Myiasis of Humans, J R Anderson Management and Control of Oestrid Flies, P J Scholl A Synopsis of the Biology, Hosts, Distribution, Disease, D D Colwell, M J R Hall and P J Scholl.

Trapping the flies that cause myiasis: their responses to host-stimuli

A critical phase in the life cycle of the fly species that cause myiasis is host location by the adult females, whether by direct location of and contact with the host, or by indirect location through the selection of sites frequented by hosts. The stimuli to which these flies respond in host location, principally visual and olfactory, are discussed here in the context of their use to enhance the performance of trapping systems used in research, monitoring and control. The three major families of flies encountered in myiasis can be divided into two groups for comparison of host-location strategies: (1) Oestridae; and (2) Calliphoridae and Sacrophagidae. The former are all obligate parasites, the latter include obligate and primary facultative parasites. In the Oestridae, the majority of Cuterebrinae deposit their eggs at sites likely to be visited by the host, whereas the majority of Oestrinae, Hypodermatinae and Gasterophilinae deposit their eggs or larvae directly onto the host. It is presumed that most host location is, like that of haematophagous insects, by response to olfactory and visual cues released by healthy hosts, but the subject is very under-researched. In the Calliphoridae and Sacrophagidae, most species that cause myiasis deposit their eggs or larvae directly onto the host at some predisposing site, such as those caused by wounding, necrosis and/or bacterial contamination. Healthy hosts are much less attractive, even for obligate species such as Wohlfahrtia magnifica, which can invade undamaged tissues. The last decade has seen a renewed interest in the potential for using traps in control of myiasis, leading to significant advances in trap and bait efficiency. However, there is great potential for further research and development, particularly on the general responses of Oestridae to hosts and in the precise identification of the olfactory cues for Calliphoridae and Sarcophagidae.

Virtual forensic entomology: Improving estimates of minimum post-mortem interval with 3D micro-computed tomography

We demonstrate how micro-computed tomography (micro-CT) can be a powerful tool for describing internal and external morphological changes in Calliphora vicina (Diptera: Calliphoridae) during metamorphosis. Pupae were sampled during the 1st, 2nd, 3rd and 4th quarter of development after the onset of pupariation at 23 °C, and placed directly into 80% ethanol for preservation. In order to find the optimal contrast, four batches of pupae were treated differently: batch one was stained in 0.5M aqueous iodine for 1 day; two for 7 days; three was tagged with a radiopaque dye; four was left unstained (control). Pupae stained for 7d in iodine resulted in the best contrast micro-CT scans. The scans were of sufficiently high spatial resolution (17.2 μm) to visualise the internal morphology of developing pharate adults at all four ages. A combination of external and internal morphological characters was shown to have the potential to estimate the age of blowfly pupae with a higher degree of accuracy and precision than using external morphological characters alone. Age specific developmental characters are described. The technique could be used as a measure to estimate a minimum post-mortem interval in cases of suspicious death where pupae are the oldest stages of insect evidence collected.

Molecular phylogenetics of tsetse flies (Diptera: Glossinidae) based on mitochondrial (COI, 16S, ND2) and nuclear ribosomal DNA sequences, with an emphasis on the palpalis group

Relationships of 13 species of the genus Glossina (tsetse flies) were inferred from mitochondrial (cytochrome oxidase 1, NADH dehydrogenase 2 and 16S) and nuclear (internal transcribed spacer 1 of rDNA) sequences. The resulting phylogeny confirms the monophyly of the morphologically defined fusca, morsitans and palpalis subgenera. Genetic distances between palpalis and morsitans subspecies suggest that their status needs revision. In particular, cytochrome oxidase 1 sequences showed large geographical differences within G. palpalis palpalis, suggesting the existence of cryptic species within this subspecies. The morphology of palpalis group female genital plates was examined, and individuals were found varying outside the ranges specified by the standard identification keys, making definitive morphological classification impossible. A diagnostic PCR to distinguish G. palpalis palpalis, G. tachinoides and G. palpalis gambiensis based on length differences of internal transcribed spacer 1 sequences is presented.

Wound myiasis of sheep in Hungary.

In Hungary, 4388 sheep in six flocks were surveyed in June-August of 1992-1995 to gather basic data on wound myiasis, its incidence, the predominant fly species involved and the clinical manifestations of infestation. The pathogenesis and economic significance of wound myiasis, as well as the interrelation of breed and sex with infestation levels, were evaluated. Active wound myiasis was recorded in all flocks, in 17.6% (774/4388) of the inspected sheep. The incidence varied among flocks and inspections from 4.7% to 38.9%, but it was significantly greater in imported breeds (28.8%, 651/2257) than in indigenous breeds (5.8%, 123/2131). Lesions of wound myiasis were located more frequently on the external genital organs (in 87%, 673/774 of all cases) than on other body regions. Overall, significantly more males (74.3%, 61/82) than females (16.5%, 713/4306) were infested. With the exception of five cases (0.06% of the total), when larvae of Lucilia sericata (Diptera: Calliphoridae) were also found, Wohlfahrtia magnifica (Diptera: Sarcophagidae) was the only species identified in wounds in this study. Despite the fact that larvae of L. sericata were so rarely encountered in wounds, adults of L. sericata were much the more common of the two species observed around wounds, even those infested by W. magnifica. The vast majority of animals inspected had only one myiasis wound. Clinical signs depended on the body part affected. The most severe infestations, in terms of extent of wounds and numbers of visible larvae, were usually those of the vulva and prepuce. Wound consisted of from one up to six foci, each completely filled by larvae of W. magnifica. These foci were either isolated from each other or they merged into a large lesion. Larvae in any focus tended to be at the same stage of development, but, were wounds were very severe, a range of developmental stages was observed together, indicating that frequent restrikes of wounds occurred. The most common signs were restlessness, anxiety and reluctance to graze. The animals were obviously depressed when they suffered from severe infestations causing lameness or blindness. Some of the most severely affected animals displayed obvious loss of condition. However, overall, there was no significant difference between the mean bodyweights of a sample of infested (59.2 kg) and uninfested (60.9 kg) animals.