Colonization of Blowflies (Diptera: Calliphoridae) and Association Time Between Adults and Immatures in Pig Carcass Decomposition: One Day to Change

Abstract

Blowflies are often the first to colonize a cadaver, making them valuable forensic indicators for estimating the post-mortem interval (PMI). However, understanding the decomposition process by blowflies in practice presents challenges due to the direct influence of adults and larvae on the process. Environmental factors can either hinder or stimulate colonization by different species, leading to variability across different settings. In this study, we aimed to investigate the variation in the community of adult and immature stages of Calliphoridae blowflies during pig carcass decomposition in an island area of the Amazon rainforest. We identified changes in abundance, richness, and species composition separately for adults and larvae and measured the congruence between larval and adult communities. Our findings revealed that the peak abundance of adults preceded the peak abundance of larvae during carcass decomposition. Eleven species were collected within the first 4 days of decomposition, of which only seven colonized the carcass. Species composition differed between life stages and decomposition phases, with larvae associated with the skeletonization phase and adults with the colliquative phase. The species composition of adults collected from the decomposing carcass corresponded to that of larvae collected 1 day later. This is the first study conducted in an Amazonian island environment in the extreme north of Brazil to document the cadaveric fauna and analyze the congruence between adult and larval communities of blowflies. These insights contribute to forensic entomology understanding and assist forensic professionals, particularly in tropical regions with high rates of unsolved homicides like Brazil.

Keywords: Calliphorids; Community congruence; Forensics; Varzea forest.