A study was carried out on the forensic entomotoxicological evaluation of carrion insects of rabbits euthanized with Acetonitrile between February and March, 2023, at the stadium of the University of Ibadan. The rabbits were obtained from The Teaching and Research farm, University of Ibadan, Oyo state.
The rabbits were then euthanized with 10ml of Acetonitrile while the control group were scarified by cervical dislocation. Adult carrion insects were collected from the carrions using a sweep net and stored in 70% alcohol. The larvae were collected into a bowl by using a scoop, immobilized with hot water and later placed in sample bottles containing 70% alcohol. Pupae were also collected using forceps immobilized with hot water and later placed in sample bottles containing 70% alcohol. Ambient and carcass temperature was measured using infrared thermometer while relative humidity was recorded with a digital hygrometer.
Calliphoridae and Muscidae were the initial pioneers of the decomposing carcass and were seen during the fresh stage, while Sarcophagidae arrived shortly after the fresh stage of decomposition. It was found that Calliphoridae was the most dominant carrion insect while Sarcophagidae was the least dominant among the pioneer. The control group had more abundance and species composition of carrion insects than the paraquat-poisoned rabbits. The length and weight of the larvae as indices of growth were also observed to be comparatively higher in the control than the 10ml acetonitrile rabbit. The highest mean temperature value for the decomposing 10ml Acetonitrile-treated rabbits was 31.90°C while its lowest mean value was 22.60°C. The highest mean relative humidity value was 99% while the least recorded was 42% due to the rainy season.
Acetonitrile was found to retard the growth of carrion larva as shown in Musca domestica when compared with the control. Overall, rapid decomposition rate was recorded due to high ambient and carcass temperatures in the tropics. It can be deduced from this study that carrion insects are essential in providing the essential ecosystem service of decomposition and can be used in solving suicide puzzles through the extrication of post mortem intervals in conjunction with environmental variables. More studies are therefore needed to test the specific effects of other commonly used suicide poisons on carrion insects in Nigeria.
Table of Contents
CHAPTER ONE INTRODUCTION
1.1 Entomotoxicology
1.2 Carrion insects
1.3 Acetonitrile
1.4 Justification for the study
1.5 Aims and objectives of the study
CHAPTER TWO LITERATURE REVIEW
2.1 Introduction
2.2 Decomposition
2.3 Insect succession
2.4 Factors affecting insect succession
2.5 Types of carrion insects and Arthropods
2.6 Acetonitrile
2.7 Review of previous literatures in Nigeria
CHAPTER THREE MATERIALS AND METHOD
3.1 Study site
3.2 Measurement of larval body length and weight
3.3 Measurement of carcass temperature and humidity
CHAPTER FOUR RESULTS
4.1 Abundance and species composition of carrion insects on rabbit carcass
4.2 Carrion insect succession on rabbit carcass
4.3 Effects of Acetonitrile on the length and weight of the control and 10ml larva.
4.4 Variations in environmental variables at the field site
CHAPTER FIVE DISCUSSION
5.1 Abundance and specie composition of carrion insects on rabbit carcass
5.2 Carrion insect succession on rabbit carcass
5.3 Effects of Acetonitrile on the length and weight of larva
5.4 Variations in environmental variables at the field site
5.5 CONCLUSION
Study Objectives & Research Focus
This study aims to conduct a forensic entomotoxicological evaluation of rabbit carcasses treated with Acetonitrile to determine its impact on carrion insect colonization, succession patterns, and larval development, thereby exploring the potential for using such data to estimate post-mortem intervals in cases of poisoning.
- Forensic entomotoxicological impact of Acetonitrile on carrion insects
- Succession patterns of arthropods on poisoned versus non-poisoned animal remains
- Correlation between toxin concentration and larval growth indices (length/weight)
- The role of environmental and climatic variables in decomposition rates
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1.1 Entomotoxicology
Entomotoxicology is derived from the words 'entomo" which means insect" and "toxicology" which means the study of poisons or toxins," so it may simply be defined as the study of toxins or poisons in insects (Amendt et al, 2004). In many parts of the world, including developing countries like Nigeria and developed countries like the United States, drug-related mortality have increased (Catts and Goff, 1992). These bodies can go unnoticed for days or weeks after they have died. The bodies are usually in the skeletonized stage of decomposition or any other stage of decomposition when there isn't enough tissue on the body to allow proper post mortem examination (Goff, 1993). However, scientists and law enforcement authorities must study the reason of the incident in some way and the type of poison used so that they can determine whether the death was caused by homicide, suicide, or drug overdose (Catts and Goff 1992).
Traditionally, there are several reports of forensic entomotoxicology programs and experiments. The forensic entomotoxicology principle dates back to the thirteenth century at least. Nevertheless, forensic entomotoxicology has only been routinely investigated in criminal investigations in the last 30 years as a practicable source of evidence.
Summary of Chapters
CHAPTER ONE INTRODUCTION: Provides the definition of entomotoxicology, characterizes carrion insects, and establishes the study's aim of observing the effects of Acetonitrile on decomposing rabbits.
CHAPTER TWO LITERATURE REVIEW: Surveys current knowledge on decomposition stages, insect succession dynamics, and the forensic relevance of specific insect families like Calliphoridae and Sarcophagidae.
CHAPTER THREE MATERIALS AND METHOD: Describes the site selection, experimental setup, preparation of poisoned rabbits, and the specific procedures for sampling insects and measuring environmental variables.
CHAPTER FOUR RESULTS: Presents the findings regarding census and species diversity of insects on treated and control carcasses, along with data on larval growth and fluctuating environmental conditions.
CHAPTER FIVE DISCUSSION: Interprets the experimental results in the context of previous studies, confirming that Acetonitrile exposure significantly affects insect population composition and developmental rates.
Keywords
Forensic Entomotoxicology, Acetonitrile, Carrion Insects, Insect Succession, Decomposition, Post Mortem Interval, Rabbit Carcass, Calliphoridae, Sarcophagidae, Muscidae, Larval Development, Nigeria, Suicide Poisoning, Toxicology, Forensic Science
Frequently Asked Questions
What is the core subject of this research study?
The study focuses on forensic entomotoxicology, specifically analyzing how the lethal ingestion of Acetonitrile affects the carrion insects that colonize and decompose a deceased organism.
What are the primary themes addressed in the work?
The main themes include decomposition biology, insect colonization succession, the impact of toxic substances on insect development, and the environmental influence on these processes.
What is the primary goal of the experimental study?
The primary goal is to assess whether Acetonitrile poisoning alters the species diversity, abundance, and growth rates of carrion insects, which would provide critical information for estimating the post-mortem interval in legal investigations.
Which scientific methods were employed?
The study used controlled experimental field conditions, collecting insects using sweep nets and hand-sorting, measuring larval physical indices (length and weight) and monitoring ambient temperature and humidity.
What topics are covered in the main body sections?
The main body covers the theoretical background of forensic entomology, detailed materials and methods, comprehensive results regarding insect abundance across stages, and a detailed discussion comparing treated vs. control results.
Which keywords best describe this research?
Keywords include Forensic Entomotoxicology, Acetonitrile, Carrion Insects, Insect Succession, Decomposition, Post Mortem Interval, and Larval Development.
How does Acetonitrile affect the larval growth of Musca domestica?
The study found that Acetonitrile significantly retards the growth of Musca domestica larvae; specifically, larvae in the control group reached greater length and weight than those on the Acetonitrile-treated rabbits.
What role does the rainy season play in this specific experiment?
The high relative humidity recorded during the study, attributed to the rainy season, impacted the environmental variables, leading to higher decomposition rates and influencing the recorded temperatures.
- Citar trabajo
- Emmanuel Tyokumbur (Autor), 2023, Forensic entomotoxicological evaluation of a normal lethal dose of Acetonitrile, Múnich, GRIN Verlag, https://www.grin.com/document/1394612
