# Composition of Necrophagous Insect Assemblages in Altitudinal Gradient of Central Chile

## TL;DR

This study examines how the types and numbers of flesh-eating insects change with elevation in central Chile, finding that blowflies are key indicators at higher altitudes.

## Contribution

The study provides baseline data on necrophagous insect assemblages across altitudinal gradients and identifies indicator species for forensic and ecological applications.

## Key findings

- Arthropod richness was highest at low and intermediate elevations.
- Blowflies like Chrysomya albiceps and Lucilia species were identified as indicator species at high elevation.
- No significant differences in abundance were found among sites for Calliphoridae or total arthropods.

## Abstract

Necrophagous insects are key organisms for studies spanning environmental monitoring and applied contexts. Here, we tested whether abundance, richness, and community composition of necrophagous arthropod assemblages differ among three sites along an altitudinal gradient (50, 1000, and 1800 masl) in the Andean cline of Central Chile. Specimens were collected by active sampling and carrion trapping. Arthropod taxon richness differed markedly among sites, with the highest diversity at low and intermediate elevations. At 1800 masl, blowflies (Diptera: Calliphoridae), including Chrysomya albiceps, Compsomyiops fulvicrura, Lucilia cuprina, and Lucilia sericata, were identified as indicator species. The presence of Calliphoridae at high elevation underscores the value of ecology-focused studies of necrophagous insect diversity and community composition for environmental monitoring and supports the use of these data to inform future research and forensic applications across altitudinal gradients.

This study evaluated whether necrophagous arthropod assemblages, with emphasis on Calliphoridae (Diptera), differ among three sites in central Chile: Coastal (50 masl), Pre-mountain range (1000 masl), and High Andean (1800 masl). We analyzed differences in the abundance, richness, and community composition of arthropods associated with decomposed bait. Specimens were collected using carrion traps and active sampling. In total, 1240 specimens (predominantly insects) were obtained across three orders: Diptera (n = 1216), Hymenoptera (n = 22), and Neuroptera (n = 1). Within Diptera, the families recorded were Calliphoridae (n = 947), Muscidae (n = 118), Piophilidae (n = 77), Fanniidae (n = 44), Sarcophagidae (n = 15), Mycetophilidae (n = 8), Phoridae (n = 5), and Ulidiidae (n = 2). No significant differences were detected in total arthropod abundance or Calliphoridae abundance among sites. Necrophagous arthropod richness was highest at the Coastal and Pre-Andean sites. For Calliphoridae, no significant differences were observed among sites for the evaluated ecological parameters. Indicator taxa at the Coastal site included Braconidae (Hymenoptera) and the dipteran families Fanniidae and Muscidae. At the High Andean site, blowflies (Diptera: Calliphoridae), including Chrysomya albiceps, Compsomyiops fulvicrura, Lucilia cuprina, and Lucilia sericata, were identified as indicators. All Calliphoridae species sampled were confirmed as potentially forensically relevant for the region due to their necrophagous habits. Beyond documenting Calliphoridae across elevation, this study provides baseline data to support future work using this taxon to assess environmental impacts, characterize local trophic interactions, and inform forensic applications.