EM - IUEM - Tecnologias Laboratoriais em Ciências Forenses
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- Survival, development and bioaccumulation rate of Calliphora vicina larvae (Diptera: Calliphoridae) to increasing concentrations of metalsPublication . Fialho, Ana Catarina Montanha; Família, Carlos; Brito, José; Mascarenhas, PauloHeavy metal poisoning is a serious threat to human health, as heavy metals are highly toxic in low concentrations. Exposure to these substances has the potential to result in chronic or acute poisoning, which can have adverse effects on human health and, in some cases, may ultimately lead to death. The analysis of heavy metals on decaying corpses can be challenging due to the interference of matrix decomposition or the absence of traditional biological samples. In such cases, forensic entomology can be a useful tool, as necrophagous insects may facilitate the detection of these substances. For example, the blowfly Calliphora vicina (C. vicina) is a common early colonizer of decomposing corpses, and thus may be a suitable candidate for use as entomological evidence. Nevertheless, these toxic substances have the potential to impact insect growth and survival rates, which may, in certain circumstances, restrict their use as toxicological markers and for post-mortem interval (PMI) estimations. The present study sought to ascertain the impact of the most prevalent heavy metals responsible for human poisoning – Arsenic (As), Mercury (Hg), Lead (Pb), and Cadmium (Cd) – on the survival, development, and bioaccumulation rate of C. vicina larvae. To this end, C. vicina larvae were reared in increasing concentrations of each heavy metal for a six-day period. The length and weight of the larvae were measured, and the concentrations were analysed using Wavelength Dispersive X-Ray Fluorescence Spectrometry (WDXRF), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), and Atomic Absorption Spectroscopy (AAS). Each heavy metal resulted in elevated mortality rates in a dose-dependent manner, with As being the most toxic for this species. The development of C. vicina larvae was found to be limited by high concentrations of all heavy metals, resulting in a reduction in weight and length, with sizes comparable to that observed in the first and second instars. The findings demonstrate that elevated concentrations of heavy metals can potentially introduce bias in PMI estimations based on entomological evidence. All metals were successfully detected on the larvae and rearing substrate. However, no evidence was established for the bioaccumulation of As, Hg, or Pb from C. vicina larvae. Verification of bioaccumulation was limited to Cd, with larvae concentrations 3 to 4 times higher than those observed in the substrate.