Seasonal, Locality, and Habitat Variation in Assemblages of Carrion-Associated Diptera in Gauteng Province, South Africa

Habitat Associations of Carrion Beetles (Coleoptera: Silphidae) Across a Full Annual Cycle

Necrophagous insects play an important role in decomposition and nutrient recycling of decomposing vertebrates. Ecological studies of carrion-associated beetles enhance forensic investigations by providing information about community assemblages and predictable patterns of succession. However, lack of standardized protocols that include replication, spatial scale, and phenology reduce detection of patterns and predictions. To address these gaps and examine the influence of habitat (woodlands vs grasslands) and abiotic factors on carrion beetle (Coleoptera: Silphidae) communities, we developed an experimental approach from broad to finer scale located within the Kansas Flint Hills across a full annual cycle (12 contiguous months). In total, 3,333 adult carrion beetles in nine species were collected from pitfall traps baited with rat carrion over thirteen 4-wk collecting periods. PERMANOVA and NMDS demonstrate that the silphid beetle community was significantly different in species composition between grassland and woodland habitats, but communities did not differ significantly in overall mean abundance, mean species richness, or mean species diversity. Two species exhibited strong habitat associations; one associated with grassland habitat (Nicrophorus marginatus F.) and one with woodland habitat (Nicrophorus orbicollis Say). Our results reveal that habitat associations of silphid beetles can be useful in forensic investigations by determining corpse relocation and in ecological studies that explore niche filtering.

Seasonal Fluctuations in Sarcophagidae (Diptera: Calyptratae) Assemblages in the Humid Chaco Ecoregion, Argentina

The seasonal fluctuations of flesh fly (Diptera: Sarcophagidae) assemblages were investigated from March 2015 to February 2016 in five habitat types in the Humid Chaco ecoregion, Chaco Province, Argentina. Three of the habitats were anthropized: an urban area, a cattle farm, and an alfalfa crop; and two were natural: a savanna and a forest. Flesh flies were collected monthly at 25 sampling points, five per habitat. In total, 5,790 male specimens comprising 55 species distributed in 15 genera were collected. The assemblage composition of flesh flies in each habitat and season was analyzed in terms of abundance, species richness, and diversity. In addition, the correlation between these community parameters and climatic factors (precipitation 7 and 14 d before samplings, temperature, and relative humidity) were evaluated in each habitat. The highest abundance and species richness of Sarcophagidae were registered in May (autumn) and June (winter), respectively. The lowest diversity values were observed between August and September (end of winter and early spring) in all habitats. However, flesh flies were present and well represented (in terms of species richness) throughout the year in all habitat types. Fluctuations in the abundance of the most abundant species collected were analyzed. The climatic factors were correlated with diversity and species richness in the urban, cattle farm, and savanna habitats. This study revealed that flesh fly assemblages differed temporally between different types of habitats in accordance with climatic factors and microclimate conditions.

Forensic entomology research and application in southern Africa: A scoping review

The use of forensic entomology is well established in the northern hemisphere, but is still emerging in the southern hemisphere, where most of the current research is not explicitly undertaken in the context of forensics. In this review, we provide an update on the current status of forensic entomology research and its application in relation to estimation of post-mortem interval in various criminal investigations ranging from murder cases, cases of human neglect and the poaching of wildlife in southern Africa, among other issues. A literature search was conducted using Google Scholar, PubMed, Scopus and EBSCOhost databases. The studies reviewed were focused on arthropod diversity during different stages of carcass decomposition, effect of seasons on the abundance and diversity of carrion feeding arthropod species during carcass decomposition, and diurnal and nocturnal oviposition of forensically important insect species during carcass decomposition. It was further observed that arthropod species that established on a decomposing carcass are potentially useful in the estimation of post-mortem interval and determining clues in cases of criminal investigations. The review confirmed the paucity of research in forensic entomology, and its application in southern Africa. Future studies on the research and application of forensic entomology in various criminal investigation scenarios – such as murder cases, human neglect, and wildlife poaching in southern Africa – are therefore needed. Significance: • Forensic entomology research and its application is lagging in southern Africa. • There is seasonal variation in the arthropod species used for estimation of post-mortem intervals in southern Africa. • Identification of arthropod species diversity in the region has potential for application in forensic investigations.

Network modularity influences plant reproduction in a mosaic tropical agroecosystem

Biodiversity influences ecosystem function, but there is limited understanding of the mechanisms that support this relationship across different land use types in mosaic agroecosystems. Network approaches can help to understand how community structure influences ecosystem function across landscapes; however, in ecology, network analyses have largely focused on species–species interactions. Here, we use bipartite network analysis in a novel way: to link pollinator communities to sites in a tropical agricultural landscape. We used sentinel plants of Brassica rapa to examine how the structure of the community network influences plant reproduction. Diptera was the most common order of flower visitors at every site. Syrphidae visits were the strongest contributor to the number of fertilized pods, while visits by Syrphidae, Hymenoptera and Lepidoptera had the strongest effect on the number of seeds per pod. Sentinel pots at forest sites were visited by more unique species (i.e. species with higher d′) than sites in other land uses, and dairy sites had more visitors that were common across the network. Participation coefficients, which indicate how connected a single node is across network modules, were strong predictors of ecosystem function: plant reproduction increased at sites with higher participation coefficients. Flower visitor taxa with higher participation coefficients also had the strongest effect on plant reproduction. Hymenoptera visits were the best predictor for participation coefficients but an Allograpta sp. (Diptera: Syrphidae) was the most influential flower visitor species in the landscape network. A diverse insect community contributed to plant reproduction and connection among nodes in this system. Identifying the ‘keystone’ flower visitor species and sites that have a strong influence on network structure is a significant step forward to inform conservation priorities and decision-making in diverse agroecosystems.

Spatial and Seasonal Distribution of Forensically Important Blow Flies (Diptera: Calliphoridae) in Makhanda, Eastern Cape, South Africa

The seasonal activity of adults of eight forensically important blow fly species [Calliphora croceipalpis (Diptera: Calliphoridae), Jaennicke, Lucilia sericata (Meigen) (Diptera: Calliphoridae), L. cuprina (Wiedemann) (Diptera: Calliphoridae), Chrysomya chloropyga (Wiedemann) (Diptera: Calliphoridae), Ch. albiceps (Wiedemann) (Diptera: Calliphoridae), Ch. marginalis (Wiedemann) (Diptera: Calliphoridae), Ch. putoria (Wiedemann) (Diptera: Calliphoridae), Ch. megacephala (Fabricius) (Diptera: Calliphoridae)] was quantified from collections in Makhanda, South Africa. Flies were collected in traps baited with chicken liver and placed in the field at eight locations for four consecutive days each fortnight for 14 mo. The seasonal distribution of each species compared well to published seasonal distributions of these blow flies elsewhere in South Africa, with evidence of year-to-year variation within seasons that might be explained by weather. This information is important for determining when and where certain species are likely to occur and will be of use in forensic investigations and myiasis management plans.

Species identification of adult African blowflies (Diptera: Calliphoridae) of forensic importance

Necrophagous blowflies can provide an excellent source of evidence for forensic entomologists and are also relevant to problems in public health, medicine, and animal health. However, access to useful information about these blowflies is constrained by the need to correctly identify the flies, and the poor availability of reliable, accessible identification tools is a serious obstacle to the development of forensic entomology in the majority of African countries. In response to this need, a high-quality key to the adults of all species of forensically relevant blowflies of Africa has been prepared, drawing on high-quality entomological materials and modern focus-stacking photomicroscopy. This new key can be easily applied by investigators inexperienced in the taxonomy of blowflies and is made available through a highly accessible online platform. Problematic diagnostic characters used in previous keys are discussed.

Longevity, Fertility and Fecundity of Adult Blow Flies (Diptera: Calliphoridae) Held at Varying Densities: Implications for Use in Bioconversion of Waste

Large numbers of flies are needed to produce the quantity of larvae required for insect bioconversion of waste. However, this 'mass-rearing' may negatively affect adult survival and reproductive output. This study assessed the suitability for mass-rearing of four blow fly species, Chrysomya chloropyga, Chrysomya chloropyga (Wiedemann), Chrysomya megacephala (F.), Chrysomya putoria (Wiedemann) and Lucilia sericata (Meigen). Flies were kept at densities of 20, 50, 100, 250, 500, and 1,000 flies per 30 × 30 × 30 cm cage with an even sex ratio. Time to 50% mortality (LT50) was recorded, and the effects of density, species, and sex on LT50, fecundity, and fertility were determined. Females survived longer than males across all species. There was evidence for a trade-off between survival and high fecundity in L. sericata and C. chloropyga at density 250. C. megacephala had low fecundity across all densities. At high densities, C. putoria had the lowest mortality and highest fecundity, making it the most suitable for mass-rearing.

Use of necrophagous insects as evidence of cadaver relocation: myth or reality?

The use of insects as indicators of post-mortem displacement is discussed in many texts, courses and TV shows, and several studies addressing this issue have been published. Although the concept is widely cited, it is poorly understood, and only a few forensic cases have successfully applied such a method. The use of necrophagous insects as evidence of cadaver relocation actually involves a wide range of biological aspects. Distribution, microhabitat, phenology, behavioral ecology, and molecular analysis are among the research areas associated with this topic. This article provides the first review of the current knowledge and addresses the potential and limitations of different methods to evaluate their applicability. This work reveals numerous weaknesses and erroneous beliefs as well as many possibilities and research opportunities.