A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2012 / Various insect taxa are known to modify bone with their mandibles, including members of the orders of Dermestidae, Tenebrionidae, Calliphoridae, Tineidae and Termitidae. Despite bone modification being a known behavioural trait of many of these taxa, little work has been done to record the distinctive ways in which they modify the bone surface, and a lack of concise descriptions of modification suites inhibits decisive identification and interpretation. The most widely inferred causal agents in palaeontological literature are either termites or dermestid beetles, whilst cockroaches as potential bone modifying agents have not yet been considered. The primary aims of this investigation were to establish whether or not cockroaches and dermestids modify bone, and if so in what ways, develop an interpretative framework to aid future researchers in the identification and differentiation between the variously reported agents of bone modifications, test whether or not the agents will modify bone of varying densities (thin cortical, thick cortical, compact and cancellous bone) or in a particular state of preservation/condition (fresh, dry, weathered or fossilised), and investigate whether or not the occurrence of insect modifications on bone can be used as a proxy to establish a broad climatic signature based on their known thermal physiological limits. A single experimental trial of 18 bone specimens were exposed to the African cockroach Periplaneta americana for a period of six months and a further four experimental trials (totalling 80 bone specimens) were exposed to the Coleopteran Dermestes maculatus for periods of four months each under the absence or presence of substrate and variable feeding conditions. Experiments were conducted within an insectary at 28° C, 40 % humidity and 12 hour light/ 12 of darkness. Subsequently, all specimens were viewed using an Olympus SZX 16 Multifocus microscope fitted with a digital camera at magnifications between 7 and 115x. Three modification types were identified for P. Americana, namely discolouration, destruction of bone and gnawing. A total of five modification types were established for D. maculatus including the occurrence of surface tunnels, destruction of bone, bore holes, surface pits (Classes 1–3) and gnawing. Three distinctive surface pits morphologies were identified; Class 1 pits are highly variable but most often semi-circular to elliptical shallow depressions with a U-shape profile with striations radiating around the outer circumference of the depression. Class 2 surface pits are semi-circular shallow depressions with randomly orientated striations occurring over the entire feature. Class 3 surface pits are irregular shaped depressions with complex profiles not associated to gnawing striations. Broad climatic signatures for both of these agents were developed based on their known physiological thermal limits. The indistinct modification signature of P. americana in combination with limited occurrence and frequency patterns may prove difficult to identify from an archaeological or palaeontological context. Periplaneta americana and D. maculatus do significant damage to aves bones, which could result in their under representation in the archaeological and palaeontological records. The highly distinctive signature as well as occurrence and frequency patterns of modifications produced by D. maculatus has enabled the reinterpretation of existing palaeontological analyses, suggesting that dermestids are in fact not responsible for reported instances in which they are suggested as the causal agent during the Mesozoic and Cenozoic.

Necrophilous insects, if correctly identified, can provide useful forensic information. Research in this area has focussed on flies and beetles remain comparatively under-studied, partly because some adult carrion beetles are difficult to identify morphologically, as are their juvenile stages, often requiring specialist expertise in both cases. Molecular taxonomy has been proposed as a solution to these problems. DNA “barcodes" are short fragments of mitochondrial cytochrome oxidase I (COI) DNA that are anticipated to delineate species. This approach is becoming increasingly popular, but has been met with varying enthusiasm from taxonomists. This thesis examines their use in identifying forensically significant beetles.The DNA barcodes of 234 specimens of 25 forensically significant southern African beetle species from seven families (Cleridae, Dermestidae, Silphidae, Staphylinidae, Scarabaeidae, Trogidae and Histeridae) were obtained. Thirty-three initial barcode amplification failures were overcome by using primers other than the standard Folmer pair, undermining the barcode concept’s hope of universal primers that would allow even non-specialists to produce barcodes. Another 150 specimens (64%) entirely failed to yield barcodes, including 18 fresh specimens of three species of Trogidae, implying another lack of universality of the barcoding protocol. The majority of the beetles clustered with confamilials on neighbour-joining and maximum likelihood trees, but 1.3% of the barcodes failed to cluster with their respective families, raising questions concerning the associating power of barcodes. The identification tools of the GenBank and BOLD on-line DNA sequence databases identified 21% of the specimens to the species level, 6% of them correctly. There was evidence of a paralogous sequence in the Cleridae that, while supporting identification now that it has been associated with a morphological identification, would hamper attempts at identification by clustering or phylogenetic analysis.Distance and haplotype network analyses of the barcodes of six widespread species showed that they are not geographically structured. Barcodes are thus unlikely to be indicators of the region of origin of a species and will not determine whether a corpse has been relocated after death. To assess whether a different mitochondrial DNA fragment might address (some of) these problems, a 2.2 kb fragment extending from the 5’ end of the COI gene to the 3’ end of the Cytochrome Oxidase II (COII) gene was analysed for nine species. It was found that, for Dermestidae, Scarabaeidae and Histeridae, higher degrees of diversity occurred downstreamof the barcode region, but the region of highest diversity in the Cleridae was in the barcode region. Thus, finding a more reliable fragment along the COI-COII region for each family may make robust and guaranteed DNA-based identification of these beetles more likely. The possibility of a forensic specimen being incorrectly or not identified based on its barcode alone exists in about 40% of cases, even with the new barcodes reported here. Forensic science sets a very high bar in assessing the performance of its techniques, and it is concluded that barcodes currently have unsettling failure rates as court-worthy evidence.

The dermestid beetle (Dermestes maculatus) has become renowned in the laboratory as an aid to skeletonization of remains, both for the zoologist and the anthropologist. However, little attention has been paid to the potential effects these insects can have on hard tissues and whether their traces may be mistaken for trauma or the effects of taphonomic processes. The use of dermestid beetles in the anthropology laboratory was tested by a choice experiment based on ASTM D3345-17, examining the behavior of D. maculatus regarding Styrofoam, wood, and two types of bone. Specifically, this project tested 1.) whether the beetles showed preference for a particular material (of wood, Styrofoam, dry bone, or green bone), 2.) whether material(s) had an impact on survivorship from the larval to adult stages, and 3.) what traces dermestids leave on skeletal remains and the variation in form of those traces. Results suggest dermestid beetles will preferentially bore pupal chambers in softer materials (Styrofoam > wood > dry bone > green bone), but preference is not absolute, as pits appear in dry bone even when softer materials are present. Preference did not appear to impact survivorship. Information on the “typical” form of dermestid trace on materials is presented, as an aid to identifying these features as resulting from taphonomic processes, as opposed to ante- or perimortem processes/events.