TABLE OF CONTENTS
Title page
ABSTRACT
TABLE OF CONTENTS
List of Abbreviations
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background to the study
1.2 Statement of the Problem
1.3 Justification
1.4 Aim and Objectives
1.4.1 Aim
1.4.2Specific objectives
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 Plants
2.1.1Mechanisms employed by plants to repel mosquitoes (Insects)
2.1.2 Advantages of plants origin (non-synthetic) insecticides
2.1.3 Role of medicinal plants in the treatment of malaria
2.2 Mosquito: Causative vector for Malaria
2.2.1Life cycle of mosquito
2.3 Malaria: Disease caused by Mosquito bite
2.3.1 The malaria parasite
2.3.2 Requirement for the prevention of malaria
2.4 Synthetic Insecticides
2.4.1 Types of synthetic insecticides
2.4.2 Side effects of synthetic insecticides
2.4.3 Toxicity of synthetic insecticides
2.4.4 Remedy
2.5Larvicides
2.6 Biological (Non-synthetic) Insecticides
2.6.1 Hyptis suaveolens (Labiatae Poits)
2.6.1.1 Composition ofHyptis suaveolens
2.6.1.2 Uses ofHyptis suaveolens
2.7Essential Oils
2.8 Monoterpenes
2.9 Sesquiterpenes
2.10 Repellents
2.11 Mechanisms employed by insects against repellents (essential oil components
2.12 Gas Chromatography-Mass Spectroscopy (GC-MS)
2.13 Fourier Transform Infra-Red (FTIR)
CHAPTER THREE
3.0 MATERIAL AND METHODS
3.1 Materials
3.1.1Plant material
3.1.2 Other materials
3.1.3 Chemicals and reagents
3.1.4 Equipment
3.2 Methods
3.2.1 Plant material collection and identification
3.2.2 Extraction of essential oil from Hyptis suaveolens leaves
3.2.3 Mosquito Breeding
3.2.4 Determination of mosquitocidal capability of the essential oil
3.2.5 Determination of mosquito repellency effect of essential oil from Hyptis suaveolens leaves. Experiment one (1)
3.2.6 Determination of mosquito repellency activity of essential oils of Hyptis suaveolens leaves on Rats. Experiment two (2)
3.2.7 Test for larvicidal effect of the essential oil (WHO, 2005) guideline
3.2.8 Characterization of essential oil
3.2.8.1 Gas Chromatography-Mass Spectroscopy (GC-MS)
3.2.8.2 Fourier Transform Infra-Red Spectroscopy (FTIR) Spectroscopic Analysis
3.2.8.3 Determination of Physicochemical Properties
i. Determination of Iodine value
ii. Determination of Saponification value
iii. Determination of Acid value
iv. Determination of Peroxide value
v. Determination of Ester value
vi. Determination of Free Fatty Acid value
3.2.8.4 Statistical analysis
CHAPTER FOUR
4.0 RESULTS
4.1 Yield of essential oils from Hyptis suaveolens leaves
4.2 Mosquitocidal capability of Essential oil from Hyptis suaveolens leaves
4.3 Repellency Effect of Essential oil from Hyptis suaveolens leaves
4.3.1Mosquito repellent potential of Hyptis suaveolens essential oil. Experiment one
4.3.2 Mosquito repellent potential of Hyptis suaveolens Essential oil. Experiment two
4.4Larvicidal effect of essential oil from Hyptis suaveolens leaves
4.5Physicochemical properties of Essential oil from Hyptis suaveolens leaves
i.Iodine value
ii. Saponification value
iii. Acid value
iv. Peroxide value
v. Free Fatty Acids value
vi. Ester value
4.6Gas Chromatography- Mass Spectroscopy (GC-MS)
4.6.1 Characterization of the Essential oils from Hyptis suaveolens by GC-MS
4.7Fourier Transform Infra-Red Spectroscopy (FTIR)
4.7.1 Characterization of the Larvicidal Compound(s) in the bioactive Fraction by (FTIR)
CHAPTER FIVE
5.0 DISCUSSION
CHAPTER SIX
6.0 CONCLUSION, SUMMARY AND RECOMMENDATIONS
6.1Conclusion and Summary
6.2Recommendations
REFERENCES
ABSTRACT
Essential oils were extracted from the leaves of Hyptis suaveolensby hydro-distillation,Mosquitocidal effect was done through an experiment devised for the purpose of this research. The effect of the essential oils against mosquito larvae (larvicidal), mosquito repellency effectand physicochemical properties were determined using standard methods. Gas Chromatography-Mass Spectrometry (GCMS) and Fourier Transform Infra-Red (FTIR) were both done on the essential oils. Percentage yield of the essential oils was gotten as 0.05, for the larvicidal activity dose dependent mortality of the larvae was observed; there was low mortality rate at lower dosage and not significantly different from each other e.g. 6.25 and 12.50ppm had same LC50 and LC90 of 25.21 and 302.67 respectively, 25ppm had LC50 and LC90 of 9.58 and 352.46 respectively, while 50-1000ppm had LC50 and LC90 of 0.55 and 0.85 respectively. It was observed that the amount of air that enters and leaves the cage affect the rate at which mosquitoes were repelled. In a group of mosquitoes kept in a cage with all sides open (ASO) 65% of the mosquitoes were repelled within 30 minutes while for one side open (OSO) and all sides closed (ASC), 73% and 85% of the mosquitoes were repelled within the same time frame. In a second experiment, 100% of mosquitoes were repelled from the surface of rats with shaven skin where essential oil was applied. The essential oil also demonstrated dose dependent mosquitocidal activity with LC50 and LC90 values of 6 and 21ppm respectively. The essential oil has the following physicochemical properties; Iodine value 23.59+0.12g/100g, saponification 100.18+0.8mgKOH/g, Peroxide value 40.00+0.02meq/kg, Acid value 3.37+0.01mgKOH/g, Ester value 34.30+1.00mg/g and free fatty acids 0.15+0.57%. GC-MS analysis revealed Terpenes to be the major organic compound present in the essential oil which was confirmed by FTIR with the O=C-O-C stretch functional group indicating the presence of terpenes. Thus, the presences of terpenes in Essential oil of Hyptis suaveolens may have contributed to its insecticidal and mosquitocidal repellency properties.
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background to the study
Plants have always served as food and medicine to man since the beginning of life. Their nutritional and medicinal potentials have been attributed to the phytochemicals and other chemical constituents contained in them. Despite their importance, it has been reported that out of the 250,000 to 500,000 species of existing plants on earth, only about 300 species are utilized in the food, pharmaceutical, cosmetics and perfume industries. Traditionally used medicinal plants produce a variety of compounds of known therapeutic properties (Umedum et al., 2014).
Medicinal plants are used in traditional treatments to cure variety of diseases. In the last few decades there has been an exponential growth in the field of herbal medicine. Natural products have been a source of drugs for centuries (Dinet al., 2011). Traditional medicines (plants source) has been used for thousands of years for the treatment of malaria and are the source of two main groups (artemisinin and quinine derivatives) of modern antimalarial drugs (Kazembe et al., 2012).
Repellents are substances applied to the skin, which prevent insects from biting such surface (Traoré-Coulibalyet al., 2013).An insect repellent is a substance that causes an organism to move away from the odour source, insects perceive thevolatile repellents by smell (Luts et al., 2014).
Essential oils are volatile natural complex secondarymetabolites characterized by a strong odour and have agenerally lower density than that of water (Arun et al., 2009). They are natural volatile mixtures of hydrocarbons with a diversity of functional groups, and their.....
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