Toxicology and fly larvae on a putrefied cadaver

Effect of Lorazepam on the Development of the Hairy Maggot Blow Fly, Chrysomya rufifacies (Macquart): Implication for Forensic Entomology

Entomotoxicology is based on using insect evidence recovered from a dead body to find out the cause and time of the death. Drugs can accumulate in fly larvae when they ingest the flesh of deceased persons and alter the normal development of the fly causing implications in calculating postmortem intervals. Lorazepam is an antidepressant generally used to treat anxiety. Larvae of Chrysomya rufifacies were fed on the beef liver mixed with lorazepam to study the effect of lorazepam on the developmental rate of larvae and to count delay in postmortem interval. Larvae grown on the beef liver with different doses of lorazepam showed delayed development as compared to normal larvae. The life cycle durations in experimental cultures with different concentrations of lorazepam completed in 1 ppm (272.56 hrs), 2 ppm (289.23 hrs), 3 ppm (324.10 hrs), and 4 ppm (350.72 hrs), while in the control culture life cycle completed in 257.26 hrs. The length, weight, and width of the larvae treated with lorazepam were smaller than the untreated culture. Length, weight, and width decreased with increased concentration of lorazepam. This delay in development ultimately affects the postmortem interval. That is why prior knowledge of the life cycle of flies with respect to various drugs needs to be studied, and these baseline data can be used to calculate postmortem interval and cause of death.

In the case of extensively putrefied bodies, the analysis of entomological samples may support and complement the toxicological results obtained with other alternative matrices

Entomotoxicological analysis is not part of routine toxicological analysis. This work aims to present two cases to illustrate the potential of entomological samples as complementary matrices to identify substances in cases of advanced putrefaction. (Case#1) A woman wasexhumed after 14 months to ascertain the exact cause of death. She died after six weeks of hospitalization because of intestinal ischemia followed by multiorgan failure. (Case#2) The corpse of a woman, known to have a psychiatric disorder, was discovered in her apartment. The state of decomposition of the body was consistent with a post-mortem period of several weeks (approximately 6 weeks). Toxicological investigations were performed in the biological and entomological samples of case#1 (hair, adipocere, brain, and pupae) and of case#2 (hair, bone, flies, and pupae) using liquid chromatography with high-resolution mass spectrometry and tandem mass spectrometry detection methods. In case#1, several drugs and metabolites were detected. In particular, the pupae analyses allowed the objectification of morphine administration, whereas morphine was only found in adipocere, but not in hair nor in brain. In case#2, the pupae analyses allowed the detection of three metabolites of quetiapine, and the flies analyses allowed the detection of valpromide, which was only detected in hair. In conclusion, the pupae and flies analyses in these two cases complemented the results obtained in the other alternative biological samples, which may guide hypotheses about the possible causes of death. Nevertheless, additional data and case reports would be of benefit to assess the value of entomotoxicology in routine forensic investigations.

Reduced body length and morphological disorders in Chrysomya albiceps (Diptera: Calliphoridae) larvae reared on aluminum phosphide-treated rabbits

Assessing the time of death based on the growth and development of insects is a critical task in forensic entomology. The rate of larvae development can be affected by a variety of toxins, including pesticides. Aluminum phosphide (AlP) is a low-cost insecticide that has yet to be tested for entomotoxicological significance, despite the fact that it is frequently the cause of fatal poisoning. In this study, we measured the body length of Chrysomya albiceps larvae reared on the carcasses of rabbits poisoned with AlP and analyzed the morphological changes of the larvae reared on the carcasses of rabbits poisoned with AlP. The concentration of AlP in the body of the larvae was significantly lower than in rabbit tissues. Insects from the AlP group had a significantly lower gain in body length. Furthermore, deformities in the larvae were found. Smaller respiratory spiracles were found, as well as a deformed small posterior end with hypogenesis of the posterior respiratory spiracles. Thus, disturbed growth and development of carrion flies found at a crime scene could indicate pesticide poisoning, such as aluminum phosphide.

Effect of Zolpidem Tartrate on the Developmental Rate of Forensically Important Flies Chrysomya megacephala (Diptera: Calliphoridae) and Chrysomya saffranea

Entomotoxicology is an emerging science in the forensic investigation of death; it now influences judicial activities. Briefly, carrion flies ingest various chemicals as they feed on a cadaver. In entomotoxicology, such toxicological compounds are qualitatively and quantitatively analyzed in insects recovered from carrion. Some of these chemicals can disrupt flies' cellular physiology, leading to acceleration or delay in their developmental rate. In this study, the effect of zolpidem-contaminated tissue on the dipteran flies Chrysomya megacephala (Fabricius 1794) and Chrysomya saffranea (Bigot 1877) was assessed. Zolpidem tartrate is a sedative-hypnotic compound commonly used to treat anxiety and sleeping disorders, but it is associated with death from suicide. The effects were tested by providing the flies with liver tissue treated with various concentrations of zolpidem tartrate. The morphological parameters and development rate for all life cycle stages of treated insects were determined and used to estimate postmortem intervals. Results showed that the morphological parameters, i.e., weight, width, and length and rate of development of C. megacephala and C. saffranea was negatively associated with zolpidem tartrate concentration of C. saffranea, were negatively associated with the concentration of zolpidem tartrate, indicating that arthropod evidence evaluation can help establish the cause and time of death.

Unexpected results found in larvae samples from two postmortem forensic cases

Purpose

In forensics, entomological specimens can be used as additional/alternative matrices to detect xenobiotics when human specimens are limited in their application. Despite some advantages over implementing putrefied human remains, most medico-legal laboratories do not include entomotoxicological procedures as routine analytical methods. We thus applied two authentic cases to evaluate necrophagous larvae’s potential as complementary matrices for toxicological analysis after extensive postmortem decomposition.

Methods

Larvae and postmortem human samples, including hair, stomach contents, pericardial fluid, liver, lung, and skeletal muscle, were collected at autopsy. Samples were analyzed by liquid chromatography–tandem mass spectrometry and liquid chromatography–quadrupole time-of-flight mass spectrometry for pharmaceutical substances, illicit drugs, and new psychoactive substances, including synthetic cannabinoids, benzodiazepines, new synthetic opioids, and stimulants.

Results

Nearly all substances detected in human specimens, including several benzodiazepines and synthetic cannabinoids, were also detected in larvae. Surprisingly, some drugs, including the new psychoactive substances EAM-2201 and U-47700, were found exclusively in larvae and hair. The benzodiazepine etizolam was detected only in liver, lungs, and stomach contents, possibly resulting from characteristic tissue distribution in humans and/or larvae.

Conclusions

Antemortem external hair contamination with synthetic cannabinoids from side-stream smoke and postmortem hair contamination with substances in putrefaction fluids can be supposed in these cases. Our findings suggest that supplementary information can indeed be gained from analyzing larvae additional to those human specimens that are typically used for toxicological analysis after extensive postmortem decomposition. Nevertheless, these results represent merely two cases, requiring in-depth studies to determine whether such findings can identify acute intoxications as possible causes of death.

Evaluation of activities of dipteran maggots on a poisoned pig cadaver at Nnamdi Azikiwe University Awka, Nigeria

Background

Forensic entomology is evolving into entomotoxicology, which is a critical approach in forensic toxicology that alternatively assesses presence of toxins in insects that have eaten a decomposing cadaver. Toxic substances in or on a dead body may accumulate in the tissues of fly maggots while feeding on the body and thus may alter their developmental rate. Thus, four out of eight healthy pigs (Sus scrofa Linn.) that weighed on the average 22.3 ± 1.9 kg were sacrificed with zinc phosphide as food poison, while the remaining four pigs were sacrificed by strangulation during the rainy and dry seasons of 2014 and 2015 respectively. Their bodies were deposited in a building to mimic indoor decomposition. The building is on 6° 15′ 18.06″ N and 7° 06′ 41.37″ E at Nnamdi Azikiwe University Awka, Anambra State, Nigeria. The effect of the zinc phosphide on the decomposition duration of the cadavers was monitored. Toxicological assessment of zinc and phosphorus on maggots found on the cadavers was performed with an atomic absorption spectrophotometer.

Findings

The zinc phosphide did not affect the decomposition duration of the cadaver and did not prolong or shortened the life cycle of the fly maggots when compared with the control (strangled pig cadaver). For the poisoned cadavers, the atomic absorption spectrophotometer detected zinc in the maggot tissues collected from them while phosphorus was not detected. Neither zinc nor phosphorus was detected in the maggot tissues collected from the strangled cadavers.

Conclusions

The study showed that the zinc component in the zinc phosphide commonly used as rodenticide in Awka can be detected in maggots collected from such a suspected poisoned cadaver. Other implications related to toxicological studies on cadaveric insects in forensic entomology and serving as alternative matrices in forensic toxicology in any questionable death were also highlighted.

Development and validation of a LC/MS method for the determination of Δ(9)-tetrahydrocannabinol and 11-carboxy-Δ(9)-tetrahydrocannabinol in the larvae of the blowfly Lucilia sericata: Forensic applications

In a number of forensic toxicological cases, Δ(9)-tetrahydrocannabinol (THC) and its metabolite 11-carboxy-delta-9-tetrahydrocannabinol (THCA) are frequently considered as contributor factors to the event. To that, a liquid chromatographic mass spectrometric method is described for the identification and quantitation of THC and its metabolite THCA in the forensically important larvae of L. sericata. Larvae of Lucilia sericata were fortified with varying concentrations of THC and THCA covering the calibration range between 10 and 500pg/mg. For the isolation of the analytes from larvae, several extraction techniques were evaluated and finally liquid-liquid extraction under acidic pH was selected using hexane-ethyl acetate (50:50, v/v) as extraction solvent. For the chromatographic separation, a Waters Symmetry® C18 analytical column was used while the mobile phase was acetonitrile-ammonium acetate (2mM) (30:70, v/v). The detection was performed using electrospray ionization source in negative mode (ESI-) and the selected ions monitored were m/z 313 for THC and m/z 343 for THCA. The proposed method which is simple and sufficiently sensitive for the detection of THC and THCA even in a single larva sampling, assisted the investigation of a forensic case.

The Autopsy and Toxicologic Deaths

Deaths from toxicologic causes is one of the main reasons for performing an autopsy. The approach to performing an autopsy involves knowledge of the scene and history, particularly for the presence of prescribed and illicit drugs. The external and internal examination, while often nonspecific, can provide specific information on route of administration and specific changes seen on naked eye and microscopic examination. Material for toxicologic analysis needs to be collected and may require discussion with the toxicology laboratory to make sure the appropriate material is sent. The opinion relating to cause and manner of death requires an analysis of all stages of the investigation. Such phenomena as postmortem redistribution and tolerance to a drug must be considered before making a determination. This paper reviews the autopsy in toxicologic death.

Entomotoxicology, experimental set-up and interpretation for forensic toxicologists

Forensic entomotoxicology studies the usefulness of insects as alternative toxicological samples. Use of insects as alternative matrix for drug detection is well documented and recommended when conventional matrices such as blood, urine or internal organs are no longer available. However, several limitations of entomotoxicology have been highlighted, especially concerning interpretation of the drug concentrations in insects on human forensic cases. In addition, the lack of knowledge in pharmacokinetic of drugs in insects, large variability of experimental set-up and toxicological analysis compromise the utility of this science. This review focuses on the current knowledge of factors influencing drug detection in insects. Reasons for the current limitations, but also recommendations for future research are discussed and proposed in this paper.

Collection of biological samples in forensic toxicology

Forensic toxicology is the study and practice of the application of toxicology to the purposes of the law. The relevance of any finding is determined, in the first instance, by the nature and integrity of the specimen(s) submitted for analysis. This means that there are several specific challenges to select and collect specimens for ante-mortem and post-mortem toxicology investigation. Post-mortem specimens may be numerous and can endow some special difficulties compared to clinical specimens, namely those resulting from autolytic and putrefactive changes. Storage stability is also an important issue to be considered during the pre-analytic phase, since its consideration should facilitate the assessment of sample quality and the analytical result obtained from that sample. The knowledge on degradation mechanisms and methods to increase storage stability may enable the forensic toxicologist to circumvent possible difficulties. Therefore, advantages and limitations of specimen preservation procedures are thoroughfully discussed in this review. Presently, harmonized protocols for sampling in suspected intoxications would have obvious utility. In the present article an overview is given on sampling procedures for routinely collected specimens as well as on alternative specimens that may provide additional information on the route and timing of exposure to a specific xenobiotic. Last, but not least, a discussion on possible bias that can influence the interpretation of toxicological results is provided. This comprehensive review article is intented as a significant help for forensic toxicologists to accomplish their frequently overwhelming mission.

Effects of malathion on the insect succession and the development of Chrysomya megacephala (Diptera: Calliphoridae) in the field and implications for estimating postmortem interval

A field study on the effects of malathion on insect succession and the development of carrion flies on corpses, and its quantitative determination from the larvae on decomposing rabbit carrion was conducted. The rabbits were treated with malathion at concentrations of lethal, half-lethal and fourth-lethal doses. Malathion altered decomposition rates and species diversity: Chrysomya megacephala (Diptera: Calliphoridae) was the most abundant adult species in all the experiments; third instar larvae of Chrysomya rufifacies (Diptera: Calliphoridae) were not found on the toxic carcasses but were collected from the control; the appearance of beetles on the treated carcass was later by 1 to 3 days than on the control carcass. Development rate of the dominated species C. megacephala larvae and pupae was observed. Stepwise increases in the period of larval development, the maximum length of larvae, and weight of pupae were observed with increasing malathion concentrations. However, there was no significant difference in the duration of the pupal stage. The differences in development rate were sufficient to alter postmortem interval estimates based on larval development by 12 to 36 hours. The time of finding fresh pupae from the fourth-lethal carcass was 12 hours later than the control. Accumulations of the pesticide in larvae were observed, but no correlations were found between larvae concentrations and the initial quantity administered to rabbits.In conclusion, it is necessary to consider the effects of malathion present in decomposing bodies when estimating the postmortem interval based on entomological evidence. The results of this study have more practical implications for forensic investigations because it is under natural conditions.

Drug analysis in blowfly larvae and in human tissues: a comparative study

The present study investigates the correlation between concentrations of drugs in human tissues and Diptera larvae feeding on these tissues. Samples of liver were taken from 18 cases in which preliminary toxicological screening indicated the presence of drugs. Blowfly larvae (Diptera: Calliphoridae) were reared on these samples and subsequently analyzed for drug content. Toxicological analyses were carried out using ONLINE Abuscreen (Roche) and GC/MS for available body fluids (blood, urine and bile) as well as liver samples and maggots. All drugs detected in human tissues were also detected in insect specimens. Opiates, cocaine and barbiturates as well as some antidepressants (clomipramine, amitryptiline, nortryptiline, levomepromezine and tioridazine) were observed. Comparisons of drug concentrations between those in human tissues and blowfly larvae showed different patterns of distribution that may be attributed to differences in physiology. Results confirm the reliability of entomological specimens for qualitative analyses, although quantitative extrapolations are unreliable. All xenobiotics detected were in higher concentrations in human tissues than in maggots. Concentrations in post-feeding maggots were significantly lower than for feeding maggots, suggesting that the feeding state of maggots may affect toxicological analyses as they metabolize and eliminate drugs during development.

The forensic entomologist in the context of the forensic pathologist's role

An adequate death investigation requires the combined efforts and cooperation of experts in different disciplines: crime scene technicians, death investigators, forensic pathologists, anthropologists, entomologists, other medical and non-medical professionals. These front-line experts play a crucial role in every death investigation process. The forensic pathologist normally has the legal authority to take charge of the dead body at a death scene and his primary functions are the exterior and interior examination of the cadaver by analyzing the extent of antemortem injuries and the postmortem changes and the recovery of physical evidence. He is responsible for determining how, when and why of any death which is the result of violence, suspicious or unexplained circumstances or a death which is sudden or unattended, defending and explaining the reasons for making these diagnoses in a courtroom. The forensic entomologist can provide invaluable aid in death cases where human remains are colonized by insects and in the overall investigation. His principal role is to identify the arthropods associated with such cases and to analyze entomological data for interpreting insect evidence. He is responsible for determining the period of insect activity according to all the variables affecting insect invasion of remains and their development. The major goal of medico-criminal entomology is to contribute to the determination of the time, cause, manner and place of the investigated death (especially on badly decomposed corpses or skeletonized human remains) with the support of all the elements which can be inferred from the study of insects found on the cadaver or nearby. The application of techniques devised recently in forensic entomology can allow experts in the field to collect strong entomological evidence and provide useful information not only in a death investigation including movement or storage of the remains following death, time of dismemberment, postmortem artifacts on the body but also at the scene, and even more in child neglect, sexual molestation and identification of suspects. As the role of the forensic entomologist at the death scene, at the autopsy and in the laboratory is defined and well known, this paper focuses on the difficulties that could arise if forensic pathologists and entomologists are uncertain about the procedures that they have to follow, do not realize the value of objective findings or fail to evaluate them. Although every forensic case presents a slightly different set of circumstances and has to be tackled individually, the forensic pathologist should work with the forensic entomologist from the visual observations of the cadaver on the scene, through the collection of arthropods and temperature data at the death scene and at the autopsy, up to the final report with the interpretation of entomological and other biological evidence.

Entomotoxicology

Entomotoxicology is a relatively new branch of forensic entomology. The potential use of insects for detecting drugs and other toxins in decomposing tissues has been widely demonstrated. In death investigations, Diptera and other arthropods can be reliable alternate specimens for toxicological analyses in the absence of tissues and fluids normally taken for such purposes. Entomotoxicology also investigates the effects caused by drugs and toxins on arthropod development in order to assist the forensic postmortem interval estimates. However, several remarks on the limitations of entomotoxicology have been highlighted recently. In this paper, the implications for the practice of this forensic procedure are fully reviewed.

Analysis of opiates in fly larvae sampled on a putrefied cadaver

Toxicological analyses on a putrefied cadaver are sometimes difficult to achieve, because of the absence of blood and/or urine. Drugs present in a decomposing corpse may be identified through analysis of maggots feeding off it. In this study, morphine and codeine were simultaneously identified and assayed in blood and bile of a putrefied cadaver and in the fly larvae of Calliphoridae found on the corpse.

Forensic entomo-toxicology

Drugs present in a decomposing corpse may be identified through analysis of maggots feeding off it. Case reports in forensic entomo-toxicology are sparse and the data base is unstructured. Drug concentrations should be measured in residual skeletal muscle, the principal food source for fly larvae, as well as in washed maggots, and the fly species should be determined. An untested possibility is the analysis of puparia or puparial cases which could extend the time frame for analysis into years or even into palaeopathology. In deaths indoors, the analysis of flies known to have emerged from the corpse is a theoretical possibility. To what extent drugs are retained in successive levels of the food chain is entirely unknown; drugs might be detectable in beetles feeding off fly larvae.