Parasitic and predatory behavior of Alysia manducator (Hymenoptera: Braconidae) on blow fly larvae feeding on an adult pig carcass in the Western Cape Province of South Africa: preliminary observations and forensic implications.

Wasps are part of the entomofauna associated with vertebrate carrion. They are known to parasitize and prey on specific life stages of insect hosts such as eggs, larvae, pupae, and/or adults associated with vertebrate carrion. However, reports of parasitic behavior of wasps on carrion-associated insect life stages and their possible forensic implications are non-existent in the Western Cape Province of South Africa. This study is part of ongoing research investigating the entomofauna and their pattern of succession on an adult pig carcass in Cape Town, South Africa. During this study, the parasitic wasp Alysia manducator was noted parasitizing and preying on blow fly larvae associated with the decomposing carcass. The arrival of A. manducator coincides with the occurrence of blow fly eggs and/or larvae on the carcass. These wasps were seen in close association with the eggs and larvae of blow flies on various parts of the carcass and some wasps were seen dragging fly larvae attached to their ovipositors away from one part of the carcass to another. Some A. manducator were also observed walking over several larvae on the carcass while exhibiting a stabbing behavior presumably in search of a host for oviposition. We suggest that the observations recorded in this study are of considerable forensic importance as the dragging effect and predatory and stabbing behavior exhibited by A. manducator could potentially disrupt the feeding and development of the fly larvae on the carcass. This could subsequently alter the process of carcass decomposition and/or affect minimum post-mortem interval estimations.

Key for the identification of third instar larvae of African blowflies (Diptera: Calliphoridae) of forensic importance in death investigations.

Blowfly larvae are the insects primarily responsible for the active stage of decomposition of exposed vertebrate remains and are the most frequently collected entomological evidence during forensic investigations of death. The necrophagous calliphorids in continental Africa that consistently develop on large vertebrate carrion include 11 species belonging to four genera: Calliphora, Chrysomya, Hemipyrellia and Lucilia. Most of these species are widespread in Africa and frequently reported on large animal carcasses and carrion and human corpses. A few keys have been compiled for identification of their third instar larvae, but none of them covers the complete set of taxa. Therefore, we provide a new comprehensive key with original illustrations of all taxonomically significant characters. The key is based on characters that should be easily observable even in poorly equipped local laboratories and is a reliable taxonomic tool for material collected in either urban or rural areas where synanthropic species predominate. However, it should be used with some caution in areas with relatively pristine natural habitats, where additional carrion-breeding species may occur. The publication of the key will significantly facilitate both medical and forensic entomological research and practice in Africa.

Incidental observation of bone modification by Crematogaster cf. liengmei (Hymenoptera: Formicidae) in Cape Town, South Africa.

Different taxa of insects have been reported to modify the skeletal remains of vertebrates during feeding or the creation of their larval and pupal chambers. Anecdotal reports on the modification of skeletal remains by ants exist but are rare. In this paper, a case of modification of bone due to the feeding activity of the ant, Crematogaster cf. liengmei (Hymenoptera: Formicidae), is reported. In November 2022, a bone was encountered incidentally in the vicinity of the Table Mountain National Park. The bone had been colonized by several individuals of Crematogaster cf. liengmei. Several ants were observed feeding on and removing bone particles and soft tissue remnants. A closer observation revealed striae/furrows on the epiphyseal ends of the bone. A 60-kg pig cadaver used in a winter decomposition trial in the same area was similarly colonized by this ant species, resulting in soft-tissue modification. Due to the similarity in the striae/furrows observed on the bone and the bitemarks inflicted by the ants on the right ear of the pig cadaver in the vicinity, it was concluded that the striae/furrows seen on the bone were created by the ants. Our observations show that Crematogaster cf. liengmei is an important taphonomic bio-agent that can contribute to the modification of skeletal remains in terrestrial environments.

Caught in the act: impact of Crematogaster cf. liengmei (Hymenoptera: Formicidae) necrophagous behavior on neonate pigs (Sus scrofa domesticus L.) in the Western Cape Province of South Africa.

Ants have been documented as part of the entomo-sarcosaprophagous community. They have been known to alter the process of carcass decomposition due to their ability to feed on fly eggs/larvae and create post-mortem skin injuries. However, studies on the impact of ants on decomposing carcasses are scarce, especially within the Western Cape Province of South Africa. This study was part of a research project that utilized two (2) neonate pig carcasses in each month of the year to establish baseline data on the insect species associated with decomposing carcasses in the Western Cape Province of South Africa. In the early spring (September 2020), mid-autumn (May 2021), and mid-winter (July 2021) trials respectively, several individuals of Crematogaster cf. liengmei colonized the pig carcasses shortly after deployment. There, they fed on the flesh of the carcasses and further inflicted bite marks and conspicuous post-mortem skin lesions. Following the reduction in the presence of Crematogaster cf. liengmei specifically in the mid-winter trial, non-vital bleeding was observed as a consequence of the skin lesions. In the early spring, mid- and late autumn (May 2021), and early (June 2021) and mid-winter trials respectively, Crematogaster cf. liengmei prevented the formation of large maggot masses, principally through the predation of fly eggs, larvae, and adults. The observations recorded in this study are of considerable importance in forensic investigations as the effect of the necrophagous behavior of Crematogaster cf. liengmei on decomposing remains can be misinterpreted by inexperienced investigators during crime scene investigations and may alter post-mortem interval estimations.

Animal Models in Forensic Science Research: Justified Use or Ethical Exploitation?

A moral dilemma exists in biomedical research relating to the use of animal or human tissue when conducting scientific research. In human ethics, researchers need to justify why the use of humans is necessary should suitable models exist. Conversely, in animal ethics, a researcher must justify why research cannot be carried out on suitable alternatives. In the case of medical procedures or therapeutics testing, the use of animal models is often justified. However, in forensic research, the justification may be less evident, particularly when research involves the infliction of trauma on living animals. To determine how the forensic science community is dealing with this dilemma, a review of literature within major forensic science journals was conducted. The frequency and trends of the use of animals in forensic science research was investigated for the period 1 January 2012-31 December 2016. The review revealed 204 original articles utilizing 5050 animals in various forms as analogues for human tissue. The most common specimens utilized were various species of rats (35.3%), pigs (29.3%), mice (17.7%), and rabbits (8.2%) although different specimens were favored in different study themes. The majority of studies (58%) were conducted on post-mortem specimens. It is, however, evident that more needs to be done to uphold the basic ethical principles of reduction, refinement and replacement in the use of animals for research purposes.

DNA barcoding of forensically important flies in the Western Cape, South Africa.

Forensic entomology aids the determination of post mortem interval based on arthropods associated with a deceased body. This relies on the accurate identification of insects that visit the body, particularly first colonisers such as Calliphoridae (Diptera). Traditional species identification though morphological keys can be challenging as immature or closely related specimens can look similar. Some of these challenges have been overcome through "DNA barcoding", which involves the sequencing of informative regions within a species' DNA and comparison to a database of reference sequences. However, reference DNA sequences of blow fly species in South Africa is currently limited. In this study, adult blow flies representing four species common to the Western Cape, South Africa (Chrysomya chloropyga, Chrysomya albiceps, Chrysomya marginalis, Lucilia sericata) were examined using morphological keys and DNA barcoding of two regions: COI and ITS2. These DNA sequences were then used as references for the successful identification of seven unknown immature specimens. Intraspecific divergence showed a maximum of 0.36% and 2.25% for COI and ITS2, respectively; interspecific divergence showed a minimum of 6.14% and 64.6% for COI and ITS2, respectively. According to these results, COI and ITS2 have sufficient discriminatory power for species-level identification for the four species studied.

How hard is hard enough? An investigation of the force associated with lateral blunt force trauma to the porcine cranium.

Blunt force trauma forms a substantial portion of deaths worldwide. However, few studies have attempted to determine the force involved with blunt force trauma to the lateral part of the head. Nor have many studies been conducted at velocities exceeding 10 m/s. The acquisition of human tissue for experimental studies is becoming increasingly difficult. As such, the current study investigates the trauma and the force involved with cranial blunt force trauma in a porcine model. Thirty whole porcine heads were subjected to single impact tests on the fronto-parietal region at velocities ranging from 10 m/s to 25 m/s. Half the specimens were subjected to impact by a short projectile resembling a hammer head and the other half were subjected to impact with a Hopkinson pressure bar (HPB). Both implements had the same impact diameter and were machined from the same material. The HPB is an apparatus commonly used in material testing. Its use to determine fracture force in whole cranial specimens is novel. Fractures appeared similar in both the hammer tests and HPB tests. Lacerations and fractures resembled the shape of the striker surface with the most common fracture observed being a semi-circular depressed fracture. The mean peak fracture force was 7760 N (± 4150 N), with a mean displacement of 3.1mm (± 1.1mm). Peak fracture forces concur well with previous studies although no clear trend appears to exist between level of trauma and peak impact force.