Efeito da cafeína no desenvolvimento de Chrysomya megacephala (Diptera: Calliphoridae), mosca-varejeira de importância forense
Carregando...
Data
2021-08-23
Autores
Calderan, Felipe Lissoni
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
A Entomologia Forense é a ciência que estuda insetos e outros artrópodes encontrados em cenas criminais, para auxiliar nas investigações. As moscas-varejeiras, principalmente as da espécie Chrysomya megacephala, são um dos insetos mais estudados na Entomologia Forense, pois estão entre os primeiros indivíduos a localizar e colonizar um corpo em decomposição. Dentro dessa ciência há uma vertente, a Entomotoxicologia Forense, que tem como foco a análise de substâncias encontradas nos insetos, pois como se alimentam de corpos em decomposição, podem acabar ingerindo pequenas quantidades dessas substâncias, caso a pessoa tenha consumido antes da morte, funcionando assim como uma matriz forense indireta. A cafeína foi a substância escolhida para o presente estudo, pois é a droga lícita mais consumida no mundo, devido, principalmente ao fato de ser um estimulante, além de aparecer na composição de muitos fármacos. Dentro da área forense, é comum o uso de técnicas toxicológicas, como o HPLC (Cromatografia Líquida de Alta Eficiência) e a Cromatografia Gasosa, para identificação e quantificação de substâncias em cadáveres e no meio ambiente. No caso da Entomotoxicologia, essas análises ocorrem nos insetos recolhidos no local do crime. Com isso, os objetivos desse trabalho foram: analisar o efeito da cafeína no ciclo de desenvolvimento de C. megacephala; e fazer a quantificação dessa substância ao longo do ciclo de vida, em todos os estágios do desenvolvimento, utilizando o HPLC. As larvas foram divididas em 5 grupos, com 250 larvas cada, e foram expostas às concentrações: 0,0000; 0,0075g; 0,0150g; 0,0300g e 0,0600g. Para analisar o efeito da cafeína, as larvas foram pesadas de 8 em 8 horas, do momento que começaram a eclodir dos ovos, até o momento em que foram colocadas para empupar. O tempo de pupação foi medido até o momento que os indivíduos adultos emergiram. Foi analisada também a sobrevivência dos adultos. Para isso, foram elaboradas tabelas de vida e a partir destas, foram calculados os valores de entropia em demografia, para cada concentração. Para fazer as análises em HPLC, amostras de larvas, pupas e adultos foram retiradas ao longo do experimento e passaram pela técnica. Os resultados obtidos mostraram que a cafeína afetou: o peso das larvas, com destaque para as que estavam na maior concentração, que apresentaram um peso menor do que as demais; o tempo de desenvolvimento dessa espécie, sendo que na maior concentração, foi mais lento quando comparado ao controle; e a sobrevivência dos adultos, principalmente a das fêmeas, sendo que elas morreram um pouco mais cedo do que os machos. Em relação às corridas em HPLC, o método se mostrou eficaz para detecção de cafeína na espécie, contudo, na maioria dos resultados não foi detectada a substância ao longo dos estágios de desenvolvimento. No âmbito forense, os resultados são importantes, uma vez que a substância escolhida interferiu no tempo de desenvolvimento, e qualquer interferência no tempo, pode interferir no cálculo do intervalo pós-morte (IPM), principal auxílio da Entomologia em investigações criminais.
Forensic Entomology is the science that studies insects and other arthropods found in criminal scenes, to assist in investigations. The blowflies, especially those of the species Chrysomya megacephala, are one of the most studied insects in Forensic Entomology, as they are among the first individuals to locate and colonize a decomposing body. Within this science there is a strand, Forensic Entomotoxicology, which focuses on the analysis of substances found in insects, as they feed on decomposing bodies, they may end up ingesting small amounts of these substances, if the person has consumed before death, functioning as well as an indirect forensic matrix. Caffeine was the substance chosen for this study, as it is the most consumed legal drug in the world, mainly due to the fact that it is a stimulant, in addition to appearing in the composition of many drugs. Within the forensic area, it is common to use toxicological techniques, such as HPLC (High Performance Liquid Chromatography) and Gas Chromatography, for the identification and quantification of substances in cadavers and in the environment. In the case of Entomotoxicology, these analyzes occur on insects collected from the crime scene. Thus, the objective of this work was: to analyze the effect of caffeine on the developmental cycle of C. megacephala; and quantify this substance throughout its life cycle, at all stages of development, using HPLC. The larvae were divided into 5 groups, with 250 larvae each, and were exposed to concentrations: 0,0000; 0,0075g; 0,0150g; 0,0300g and 0,0600g. To analyze the effect of caffeine, the larvae were weighed every 8 hours, from the moment they started to hatch from the eggs, until the moment they were placed to pupate. Pupation time was measured up to the time the adult individuals emerged. Adult survival was also analyzed. For this, life tables were elaborated and from these, the values of entropy in demography were calculated for each concentration. To perform the HPLC analysis, samples of larvae, pupae and adults were taken throughout the experiment and passed through the technique. The results obtained showed that caffeine affected: the weight of larvae, especially those that were in the highest concentration, which had a lower weight than the others; the development time of this species, in the highest concentration, was slower when compared to the control; and the survival of adults, especially females, as they died a little earlier than males. Regarding the HPLC runs, the method proved to be effective for detecting caffeine in the species, however, in most results, the substance was not detected throughout the development stages. In the forensic scope, the results are important, since the chosen substance interfered in the development time, which can miscalculate the post-mortem interval (IPM), the main aid of Entomology in criminal investigations.
Forensic Entomology is the science that studies insects and other arthropods found in criminal scenes, to assist in investigations. The blowflies, especially those of the species Chrysomya megacephala, are one of the most studied insects in Forensic Entomology, as they are among the first individuals to locate and colonize a decomposing body. Within this science there is a strand, Forensic Entomotoxicology, which focuses on the analysis of substances found in insects, as they feed on decomposing bodies, they may end up ingesting small amounts of these substances, if the person has consumed before death, functioning as well as an indirect forensic matrix. Caffeine was the substance chosen for this study, as it is the most consumed legal drug in the world, mainly due to the fact that it is a stimulant, in addition to appearing in the composition of many drugs. Within the forensic area, it is common to use toxicological techniques, such as HPLC (High Performance Liquid Chromatography) and Gas Chromatography, for the identification and quantification of substances in cadavers and in the environment. In the case of Entomotoxicology, these analyzes occur on insects collected from the crime scene. Thus, the objective of this work was: to analyze the effect of caffeine on the developmental cycle of C. megacephala; and quantify this substance throughout its life cycle, at all stages of development, using HPLC. The larvae were divided into 5 groups, with 250 larvae each, and were exposed to concentrations: 0,0000; 0,0075g; 0,0150g; 0,0300g and 0,0600g. To analyze the effect of caffeine, the larvae were weighed every 8 hours, from the moment they started to hatch from the eggs, until the moment they were placed to pupate. Pupation time was measured up to the time the adult individuals emerged. Adult survival was also analyzed. For this, life tables were elaborated and from these, the values of entropy in demography were calculated for each concentration. To perform the HPLC analysis, samples of larvae, pupae and adults were taken throughout the experiment and passed through the technique. The results obtained showed that caffeine affected: the weight of larvae, especially those that were in the highest concentration, which had a lower weight than the others; the development time of this species, in the highest concentration, was slower when compared to the control; and the survival of adults, especially females, as they died a little earlier than males. Regarding the HPLC runs, the method proved to be effective for detecting caffeine in the species, however, in most results, the substance was not detected throughout the development stages. In the forensic scope, the results are important, since the chosen substance interfered in the development time, which can miscalculate the post-mortem interval (IPM), the main aid of Entomology in criminal investigations.
Descrição
Palavras-chave
Ciclo de desenvolvimento, Entomologia forense, HPLC, Development cycle, Forensic entomology, HPLC