Host Breadth, Organic-Resource Use, and Quantitative Variation in Pupal Parasitism by Pachycrepoideus vindemmiae (Hymenoptera: Pteromalidae) in Brazil

Pachycrepoideus vindemmiae (Rondani, 1875) (Hymenoptera: Pteromalidae) is a solitary pupal parasitoid of Diptera associated with a broad range of hosts and organic resources. This study integrated and critically reanalyzed experimentally verified Brazilian records of P. vindemmiae to evaluate host breadth, substrate use, geographic occurrence, and variation in realized pupal parasitism. Records were screened to exclude duplicate publications, unresolved associations, and datasets lacking sufficiently traceable host-parasitoid evidence. The retained matrix comprised 47 positive host-resource records distributed among 19 principal experimental units and included feces, manure, bovine tissues, fish, food residues, fruits, and carrion. Host associations involved Diptera from several families, including Calliphoridae, Drosophilidae, Fanniidae, Muscidae, Phoridae, Sarcophagidae, Sphaeroceridae, Syrphidae, and Tephritidae. Pupal parasitism varied markedly among host-resource combinations, ranging from very low values in some cattle-dung and animal-tissue systems to substantially higher levels in selected fish-, fruit-, human-feces-, and chicken-feces-associated hosts. Four independent experimental units provided sufficient host-level data for Pearson chi-square analyses. Significant heterogeneity in pupal parasitism was detected in Morrinhos chicken feces, Caldas Novas at 740 m, Tupaciguara, and Itumbiara human feces, with Cramer's V values indicating variable but biologically relevant host-level structure. The results demonstrate that the ecological breadth of P. vindemmiae is accompanied by strong context dependence and that host abundance alone does not explain realized parasitism. Its repeated association with synanthropic, agricultural, veterinary, and carrion-associated Diptera reinforces its ecological importance and potential value in biological-control studies. However, the marked variation among experimental systems indicates that practical use should consider host suitability, substrate characteristics, environmental conditions, and local host-parasitoid dynamics.