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.

Sarcosaprophagous Muscid Fly (Diptera: Muscidae) Assemblages Along an Anthropized Gradient in the Humid Chaco Ecoregion, Chaco Province, Argentina.

Deforestation, agriculture, farmyard animal husbandry, and urbanization are known to be the main causes of biodiversity loss and habitat fragmentation. The present study evaluated the role of anthropization in modulating Muscidae (Diptera) assemblages in the Humid Chaco ecoregion of Argentina, by testing the biotic homogenization and intermediate disturbance hypotheses. The study focused on natural, rural, and urban habitats in San Lorenzo Department, Chaco Province, where sarcosaprophagous muscid flies were surveyed. A total of 1,343 muscid flies were captured and identified to 7 genera and 24 species and morphospecies. We observed the effect of anthropization on the structuring of the assemblages and the presence of exotic species associated with human activity resulting from biotic homogenization. The highest abundance was recorded in the urban habitat, while the highest species richness and diversity (Shannon-Wienner and Hill's numbers) were found in the rural habitat, supporting the intermediate disturbance hypothesis. Several species are classified as indicators of habitat as well as according to their index of synanthropy. Our results provide valuable information about the use of sarcosaprophagous muscids as indicators of disturbance of natural habitats and about possible health risks related to this family of Calyptratae flies previously unsurveyed in northeastern Argentina. This information could be used in the ecological, agronomy, sanitary, and forensic fields.

Blow flies, synanthropy and sex ratio: Are the deviations in the sex proportion linked to human transformation of landscapes?

In most species, several factors like time of emergence, age at maturation, reproductive life span, survival of males and females, mating behavior, differential resource use, and migration patterns may affect the adult sex ratio. Anthropogenic landscape transformation is known to change diversity, favoring colonization by exotic species but other populational parameters, such as the sex ratio, have not been assessed. The aim of the present study was to describe the sex-ratio patterns of adult necrophagous blow flies captured using carrion-baited traps along habitats representing different levels of human impact. We describe the sex bias for four species: the exotic Chrysomya albiceps, Chrysomya megacephala, Chrysomya putoria, and the native Cochliomyia macellaria. Three types of habitats were selected: highly anthropized (urbanized), moderately anthropized (rural), and native forest (natural) within a humid subtropical ecoregion in Northeastern Argentina. We found an overall trend to female bias among the four species when considering the total number of each sex. However, our study showed a changing sex-ratio pattern along the gradient of human influence. Our results indicate that a higher likelihood of trapping more males in unsuitable habitats seems to be widespread among blow flies. Urban exploiters, such as Ch. megacephala and Ch. putoria, locally shifted their trends, becoming male-biased in natural habitats. The opposite trend was detected in the urban avoider Co. macellaria (which shifted to male-biased in urban habitats). The exception was Ch. albiceps, whose sex proportion did not shift to a male-biased sex ratio. The results of this study highlight the changing sex-ratio patterns displayed by Calliphoridae in response to different conditions along a human-influence gradient. The biological traits and underlying mechanisms promoting the intraspecific changes of the sex ratio are discussed.