Evaluation of environmental and local factors on urban sarcosaprophagous Diptera: a case study with Sarcophagidae

Urban landscape as a determinant of sarcosaprophagous fly assemblages of sanitary interest: a comparative field study between larviparous and oviparous reproductive strategies

In Diptera, reproductive strategies vary according to the stage of development of the newly deposited offspring and their abundance. The aim of our study is to establish connections between the reproductive strategies of flies (larviparous or oviparous) and the prevailing local conditions (sun or shade) as well as landscape attributes (low or high urbanization) in an urban setting. We collected flies using 2 baited traps (in the sun or shade) at each of the 13 study sites with varying levels of urbanization. We used generalized linear mixed models to examine the impact of landscape and local characteristics on the diversity (abundance and richness of larviparous and oviparous Diptera) of sarcosaprophagous flies. Our findings indicate that while the abundance and diversity of both larviparous and oviparous flies are affected by urbanization, larviparous flies would be less sensitive to more urbanized environments. Larviparous also exhibit a preference for resources under sun exposure, while the responses of oviparous seem more species-dependent. The observed patterns can be explained by the known biology of the studied groups.

Diversity response of necrophagous dipteran communities and their functional groups to an anthropization gradient

The anthropization process exerts a profound effect on ecosystems, causing alterations in biodiversity, habitat structure, and species composition, ultimately disrupting the delicate balance of natural environments. The aim of the present study was to explore the ecological dynamics of necrophagous Sarcophagidae and Calliphoridae flies along an anthropization gradient. This research investigated alpha and beta diversity patterns to unravel the impact of human-induced environmental changes on these insect communities and also assesses the dynamics of functional groups in relation to their impact on medical and forensic fields. Five distinct habitats, ranging from urban to forested areas, were surveyed in two Departments in the Province of Chaco, Argentina. Necrophagous flies were collected using van Someren-Rydon canopy traps across three seasons. Two main functional groups were analyzed: oviparous flies (Calliphoridae) and larviparous flies (Sarcophagidae). Results indicated a significant negative correlation between Sarcophagidae species richness and anthropization, whereas Calliphoridae showed increased abundance in highly anthropized sites. The combined assemblage of Calliphoridae+Sarcophagidae exhibited significant relationships across all community parameters evaluated. Beta diversity analysis revealed turnover as the main process shaping dipteran communities along the anthropization gradient, with spatial species replacement dominating. This underscores the importance of interspecific spatial segregation in dipteran community composition. In conclusion, this study enhances our understanding of the ecological adaptations of necrophagous dipterans to anthropogenic disturbances. The observed shifts in diversity and abundance have implications for forensic investigations and public health, emphasizing the need for nuanced monitoring and conservation strategies. This research contributes valuable insights into the intricate ecological interactions of these insect communities within changing ecosystems.

Necrophagous flies as bioindicators in Cd and Zn co-contaminated areas of Tak Province, Thailand

Necrophagous flies may be effective bioindicators of chemical substances within polluted locations, as they are sensitive to environmental changes, have large populations, and thrive in a single location over their lifespan. Diversity and abundance of necrophagous flies were determined at livestock farms contaminated with potentially toxic elements (PTEs) in Tak Province and Nakhon Sawan Province, Thailand. Substantial soil zinc (Zn) concentrations (> 1100 mg kg-1) were detected at a cattle farm at Khaothong, Nakhon Sawan Province, and soil cadmium (Cd) values were significantly elevated (> 3 mg kg-1) at a cattle farm in Pha De, Tak Province. Anthropogenic inputs including Zn mining, domestic wastewater, and certain materials used in local agriculture were point sources of PTEs at the livestock farms in the Pha De and Khaothong subdistricts. Lower temperatures and humidity during the rainy season may have resulted in increased numbers of necrophagous flies, which was 1.5 times greater compared to the dry season. However, the dry season exhibited a higher PTE buildup in fly tissue. The order of important value index (IVI) values of the necrophagous flies were: Chrysomya megacephala (56.80), Musca domestica (27.21), C. rufifacies (25.40) and Sarcophaga spp. (17.54), respectively. These necrophagous flies may play a significant role in PTE-contaminated ecosystems based on their high IVI values, suggesting that they could be used as bioindicators of PTEs. Principal component analysis (PCA) results for necrophagous flies associated with each sampling site during the dry season were consistent with flies having substantial IVI values. Musca domestica and C. megacephala of both sexes displayed substantial correlations with Cr, Al, and Mn, while females of Sarcophaga spp. displayed strong associations with Cd. At the cattle farm in Khaothong, males of M. domestica showed a significant relationship with Zn, Cu, Pb, and Ni. When considering PTE accumulation capacity in flies commonly found at field sites, C. megacephala and M. domestica are the most suitable bioindicators of PTEs. This study confirms that necrophagous flies serve as reliable bioindicators of PTE pollution.

Effect of Vegetation Types on Sarcophagidae (Diptera) in Ciervo de los Pantanos National Park, a Natural Remnant in a Highly Endangered Landscape

Species diversity can be affected by the structure of vegetation, which may vary in height, density, and distribution of trees, shrubs, and other plant types, configuring different types of habitats. In this study, we evaluated the diversity of sarcosaprophagous Sarcophagidae communities inhabiting the remnant representative habitats protected in Ciervo de los Pantanos National Park: grasslands, forests, and wetlands. We hypothesized that the abundance and diversity of flesh flies would be higher in the grasslands and wetlands than in the forest patches. Samplings were carried out in each habitat type using baited traps during the four seasons in 2015, 2016, and 2019. We collected 585 sarcophagid flies of 17 species. Fifteen species were recorded in grasslands, twelve in the wetlands, and seven in the forests, Tricharaea (Sarcophagula) occidua (Fabricius) (Diptera: Sarcophagidae) being the most abundant (58.3% of the total sample). As expected, the highest abundance was recorded in grasslands whereas the lowest was found in forests. In addition, flesh fly abundance was affected by season. Sarcophagid assemblages differed between habitats and the overall dissimilarity was mainly explained by nestedness. This study provides important information about sarcosaprophagous sarcophagid flies in a little-studied protected natural area in Argentina, which is fundamental for their conservation and useful in forensic investigations.