Decomposing Resources Structure Parasitoid–Host Associations in Forensically Important Diptera: A Quantitative Synthesis from Brazil

Parasitoids constitute an additional trophic component of decomposition-associated insect communities, but their quantitative influence on forensically relevant Diptera is often difficult to interpret because historical studies differ in resource type, host composition, sampling design, and numerical reporting. This study quantitatively synthesized experimental records of hymenopteran parasitoids associated with Diptera developing in decomposing organic resources in Brazil, with emphasis on Goiás and complementary carrion records from Minas Gerais. The host pupa was retained as the principal biological unit, and realized parasitism was calculated exclusively from confirmed parasitized pupae rather than from emerged parasitoid adults. Host–resource strata, environmental contrasts, carrion-associated records, and binary host–parasitoid associations were evaluated separately to avoid duplication and inappropriate pooling of heterogeneous datasets. Realized parasitism varied markedly among host–resource combinations. In Oxysarcodexia thornax (Walker 1849) (Diptera: Sarcophagidae), parasitism differed significantly among human feces, bovine liver, and fish, whereas Peckia chrysostoma (Wiedemann, 1830) (Diptera: Sarcophagidae) showed significantly greater parasitism in chicken-derived material than in human feces. Cattle dung from southern Goiás also showed greater realized parasitism than cattle dung from central Goiás. Corrected host–parasitoid contingency analyses demonstrated significant non-random association structure in bovine, buffalo, and chicken feces. The core Goiás forensic network contained 15 dipteran host taxa, 25 parasitoid taxonomic records, and 79 binary associations, with Pachycrepoideus vindemmiae (Rondani, 1875) (Hymenoptera: Pteromalidae) showing the broadest recorded host distribution. Carrion studies confirmed parasitoid occurrence directly in forensic-resource assemblages. Association-specific records further demonstrated that parasitoid adult production could substantially exceed the number of parasitized host pupae, confirming that adult emergence and realized host exploitation are biologically distinct responses. Overall, decomposing-resource identity, host occurrence, environmental context, and parasitoid assemblage composition jointly structured parasitoid–Diptera interactions. Parasitoids may modify the composition of recovered forensic insect evidence, but the available data do not support their direct use as correction factors for postmortem-interval estimation.