This thesis wants to develop an understanding of the effects of Gammalin-20 on forensically relevant insect species found on poisoned rabbit carrion, and their changes in abundance, rate of development, and succession order.
In a study conducted at the University of Ibadan, the entomotoxicological appraisal of carrion insects found on rabbits poisoned with Gammalin-20 was carried out. Two rabbits were used as surrogate human models, with one euthanized with Gammalin-20 and the other serving as a control. The flies and larvae found on the carcasses were collected and stored in alcohol. It was found that Calliphoridae were the most dominant carrion insects, while Sarcophagidae were less dominant. The control group had a greater diversity and species composition of carrion insects compared to the Gammalin-20 poisoned rabbits. Growth indicators like length and weight of the larvae were also comparatively higher in the control group. Temperature and humidity measurements were also conducted. The effects of the poison on the developmental and succession patterns of the insects were also examined.
Table of Contents
CHAPTER ONE
INTRODUCTION
1.1 Forensic Entomology
1.2. Gamalin-20
1.3. Justification for the study
1.4. AIMS AND OBJECTIVES OF THE STUDY
CHAPTER TWO
LITERATURE REVIEW
2.1. Forensic entomotoxicology
2.2. Subdivisions of forensic entomology
2.2.1. Medico-legal forensic entomology
2.2.2. Stored-product forensic entomology
2.2.3. Urban forensic entomology
2.3 Decomposition
2.4. SUCCESSION OF INSECTS
2.5. Factors Influencing Carrion Insects Development
2.5.1. Temperature and Humidity
2.5.2. Light
2.5.3. Drugs
2.5.4. Habitat
2.6. Arthropods Associated With Carcass
2.6.1. Sarcophagidac
2.6.2. Calliphoridae
2.6.3. Dermestidae
2.6.4. Silphidae
2.6.5. Cleridae
2.6.6. Staphylinidae
2.6.7. Muscidae
2.6.8. Taxonomy of carrion insects
2.6.9. Brief Review of Identification Keys
2.7. Forensic Entomotoxicology
2.7.1. Application of Forensic Entomotoxicology
2.7.2. Review of Previous Studies
2.7.3. Gammalin 20
CHAPTER THREE
MATERIALS AND METHODS
3.1. STUDY SITE
3.2. Sample collection and processing
3.2.1. Sampling for insects
3.2.2. Sampling for maggots
3.2.3. Sampling for pupa
3.2.4. Measurement of environmental variables
3.3. Sample analyses
CHAPTER FOUR
RESULTS AND DISCUSSIONS
4.1. Abundance and species composition of carrion insects on Rabbit carcass
4.2. Effect of Gamalin 20 on the length and weight of larva.
4.3. Variations in environmental variables at the study site.
CHAPTER FIVE
DISCUSSION
5.1. Abundance and species composition of carrion insects on rabbit carcass
5.2. Carrion insect succession on rabbit carcass
5.3. Effect of Gamalin on the length and weight of larva
5.4. Variations in environmental variables at the study site
5.5. Conclusion and Recommendation
Objectives and Research Themes
The primary objective of this study is to perform a forensic entomotoxicological appraisal by analyzing insect succession, abundance, and larval development on rabbit carcasses poisoned with the organochlorine pesticide Gammalin-20, in contrast to a control group, to evaluate the impact of this toxin on post-mortem interval estimation.
- Impact of Gammalin-20 on insect colonization patterns and developmental rates.
- Assessment of species diversity and abundance of carrion-associated insects.
- Comparative analysis of larval growth (length and weight) between control and poisoned models.
- Influence of local environmental variables (temperature, humidity) on decomposition and insect activity.
Excerpt from the Book
2.5. Factors Influencing Carrion Insects Development
Several factors affect the composition and development of carrion insects. These factors include, insect succession, pace of decomposition, biogeoclimatic zone, temperature, humidity, type of organism, carcass developmental stage, and carcass physical state are all elements that influence the makeup of carrion communities (Mann et al. 1990), (Anderson 2010; Hanski 1987).
The factors impacting insect activity associated with decomposing human remains have been established. The actual insect colonization, development, and associated succession were coupled with factors impacting the insect(s) directly as well as environmental conditions such as temperature, light, access to the remains, and precipitation also influence the behaviour of forensically-important insects (Byrd and Casmer; 2010). Other determinants, such as microbial colonization and physiology associated with the remains or with the insects, are now recognized as important influences on the behaviour of forensically-relevant arthropods. Understanding insect population dynamics can be very challenging due to the large number of biotic and abiotic factors that must be taken into account. Of these factors, weather is generally considered to be one of the most important. For example, temperature, rainfall, relative humidity and other weather-related factors can strongly affect the survival, development, fecundity and behaviour of individual insects. Each developmental stage takes a known amount of time, depending on the temperature and availability of food. Temperature is especially essential since insects are 'cold-blooded,' which means that when the temperature rises, their metabolic rate increases and their development time lowers, and vice versa (Sayle, 1928).
Summary of Chapters
CHAPTER ONE: INTRODUCTION: This chapter outlines the fundamental concepts of forensic entomology and entomotoxicology, introduces the pesticide Gammalin-20, and defines the research objectives regarding its impact on carrion insects.
CHAPTER TWO: LITERATURE REVIEW: This section provides an overview of existing research on decomposition processes, insect succession patterns on carcasses, and the application of entomotoxicological data in criminal investigations.
CHAPTER THREE: MATERIALS AND METHODS: This chapter details the field approach, including the use of rabbit carcasses as human surrogates, the administration of the lethal dosage of Gammalin-20, and the protocols for sampling insects and environmental variables.
CHAPTER FOUR: RESULTS AND DISCUSSIONS: This chapter presents the data gathered from the field trials, illustrating the differences in insect abundance, species composition, and larval growth metrics between the control and poisoned carcass groups.
CHAPTER FIVE: DISCUSSION: This chapter contextualizes the experimental findings within existing literature, confirming that toxins like Gammalin-20 significantly delay colonization and larval development, and concludes with recommendations for future PMI estimation protocols.
Keywords
Forensic Entomology, Entomotoxicology, Gammalin-20, Lindane, Carrion Insects, Postmortem Interval, PMI, Decomposition, Insect Succession, Rabbit Carcass, Diptera, Calliphoridae, Sarcophagidae, Larval Development, Toxicity Estimation.
Frequently Asked Questions
What is the core focus of this research?
This research focuses on forensic entomotoxicology, specifically examining how the pesticide Gammalin-20 (containing Lindane) affects the colonization and development of carrion insects on vertebrate remains.
Which insect groups are primarily examined?
The study primarily examines Diptera (families Calliphoridae, Sarcophagidae, and Muscidae) and Coleoptera, which are identified as having high forensic importance for estimating post-mortem intervals.
What is the central research question?
The research asks to what extent the presence of a lethal organochlorine toxin (Gammalin-20) in a corpse alters the standard insect succession patterns and developmental rates, potentially leading to errors in determining the time since death.
Which methodology was applied?
The study deployed two rabbit carcasses as surrogate models in an outdoor setting: one was treated with a lethal dose of Gammalin-20, and the other served as a toxin-free control. Insects were collected daily until complete skeletonization.
What does the main body of the work cover?
The main body comprises a review of forensic entomology history, detailed methods for insect sampling and environmental monitoring, and a comprehensive quantitative analysis of insect diversity, abundance, and larval growth parameters.
Which keywords characterize this work?
Key terms include Forensic Entomology, Entomotoxicology, Gammalin-20, Postmortem Interval (PMI), Insect Succession, and Carrion Insects.
How does Gammalin-20 affect insect colonization?
The study concludes that the presence of Gammalin-20 acts as a deterrent, delaying the arrival of initial colonizing flies and subsequently slowing down the growth rate of the larvae feeding on the poisoned tissue.
How do environmental variables influence the findings?
The study notes that while high ambient temperatures typically accelerate decomposition, the presence of the poison provides a counter-effect that slows down the life cycles of the associated insects, which must be accounted for in forensic calculations.
- Quote paper
- Emmanuel Tyokumbur (Author), 2023, Lindane Effects on Carrion Insects. A Forensic Entomotoxicological Appraisal Using Euthanized Rabbits, Munich, GRIN Verlag, https://www.grin.com/document/1364231
