LARVICIDAL AND REPELLENT ACTIVITIES OF FORMULATED OINTMENTS FROM LANTANA CAMARA (VERBENACEAE) AND OCIMUM GRATISSIMUM (LAMIACEAE) LEAVES EXTRACTS AGAINST AEDES AEGYPTI (DIPTERA: CULICIDAE)

Description

ABSTRACT

The larvicidal and repellent activities of formulated ointments from Lantana camara and Ocimum gratissimum leaves extracts were investigated against fourth instar larvae and adult of Aedes aegypti in individual and combined forms using the WHO protocol Plant materials were extracted by cold maceration method in aqueous methanol to obtain the methanol crude extract MCE and successively fractionated to obtain the nhexane fraction HF, chloroform fraction CF, ethyl acetate fraction EAF and the methanol fractionMF The results of the larvicidal investigation showed that in single forms of L camara, the LC50 values of solvent extracts/fractions were as follows: 062, 072, 096 ,220, and 336 g/L for ethyl acetate, nhexane, methanol crude, chloroform and methanol respectively For O gratissimum: the LC50 values of solvent extracts/fractions were 037, 060, 097, 160, and 323 g/L for nhexane, methanol crude, ethyl acetate, chloroform and methanol respectively The combination of the nhexane fraction from the two plants and nhexane O gratissimum combined with ethyl acetate L camara showed synergistic actions However, the ethyl acetate combination L camara O gratissimum and ethyl acetate from O gratissimum combined with nhexane from L camara exhibited antagonistic effects For the repellent test, all the formulations gave protection against mosquito bites without any allergic reaction to the test persons Maximum efficacy was observed in the MCE and EAF of O gratissimum in the single tests while the MCE and HFcombinations showed synergistic effect From the results it can be concluded the MCE, HF and EAF formulations of O gratissimum and L camara leaf are potential for controlling mosquitotransmitted diseases especially the ones transmitted by vector mosquito, Ae Aegypti Moreover, identifying the synergist compounds within mixtures may lead to the development of more effective biorepellents as well as the use of smaller amounts in the mixture to achieve satisfactory levels of efficacy in reducing the Ae aegypti population, especially in the areas where surveillance and supervisory mechanism are poor or insufficient

TABLE OF CONTENTS

Title Page i

Certification ii

Dedication iii

Acknowledgement iv

Table of Content v

List of Figures ix

List of Tables xi

List of Abbreviations xii

Abstract xiii

Chapter One: Introduction 1

11 Mosquito Biology 2

111 Lifecycle 3

112 Mosquito breeding sites 10

113 Arbovirus diseases 10

12 Mosquito control strategies 12

121 Control of mosquitoes which breed near human habitation 13

122 Control of mosquitoes over a large area 15

123 Mosquito control measures 16

1231 Chemical based control measures 16

12311 Insecticideimpregnated paint IIP 16

12312 Insecticide impregnated bednets IIB 17

1232 Nonochemical based control measures 17

12321 Surface active agents SAA 17

12322 Expanded polystyrene beads EPS 18

12323 Insect growth regulators IGRs 18

12324 Genetic manipulation SIT 19

1233 Biological control agents 19

12331 Bacterial agents 20

12332 Larvivorous fishes 20

12333 Protozoa 21

12334 Predatory mosquitoes 21

12335 Viruses 21

12336 Enteropathogenic Fungus 22

13 Natural products with mosquitocidal potentials 23

14 Larvicidal phytochemicals 23

141 Mechanisms of larvicides 24

15 Insect Repellent Activity of Medicinal Plants 25

16 Integrated Mosquito Management IMM 26

17 Joint action and toxicity of insecticides 26

18 Lantana Camara 28

181 Taxonomy 28

182 Plant description 29

183 Geographical distribution 31

184 Ethnopharmacology 31

185 Phytochemical composition 31

186 Pharmacological studies 32

19 Ocimum gratissimum L 32

191 Local names 32

192 Taxonomy 33

193 Botanic description 33

194 Phytochemical composition 35

195 Ethnopharmacology and Pharmacological studies 35

110 Statement of problem 36

111 Aims and objectives 38

CHAPTER TWO: EXPERIMENTAL 39

211 Instrumentation and glasswares 39

212 Solvents and reagents 39

213 Plant and animal materials 39

22 METHODS 40

221 Collection and preparation of plant materials 40

222 Extraction of plant materials 40

223 Preparation of plant extract concentration 40

23 Colonization of mosquito vectors 41

231 Source of eggs 41

232 Maintenance of Larvae 41

233 Maintenance of pupae and adults 41

24 Larvicidal Bioassay 42

241 Larval toxicity test of plant extracts and fractions 42

242 Determination of synergistic factors SF 43

25 Repellent Bioassay 43

251 Preparation of repellent product 43

252 Preparation of mosquitoes 46

253 Recruitment of Volunteers 46

254 Preparation of human volunteer for repellent test 46

255 Determination of landing time 46

256 Concentration Finding Experiments 47

257 Repellence test procedure 48

26 Adverse effect of the formulations on the skin of human volunteers 48

27 Statistical analysis 48

CHAPTER THREE: RESULTS AND DISCUSSION 50

31 Yields of the extracts and fractions 50

32 Larval toxicity tests 52

321 Larval toxicity tests of Lcamara 52

322 Larval toxicity tests of Ogratissimum 59

323 Larvicidal combination experiments 66

33 Statistical analysis of larval toxicity 69

331 Logprobit analysis of the single larval toxicity test 69

332 Logprodit analysis of the combination bioassay and synergistic factors 72

34 Repellence tests 74

341 The landing time 74

342 Repellence rate concentration Finding experiments 74

3421 Repellence rate of O gratissimum 74

3422 Repellence rate of L camara 76

3423 Repellence rate of Combination Bioassay 79

343 Comparison of the percentage protection time of extracts and fractions 81

3431 Percentage protection time of methanol crude extracts MCE 83

3432 Percentage protection time of hexane fractions HF 85

3433 Percentage Protection Time of Ethyl Accetate Fractions EAF 87

35 Adverse Effect of the Formulations on the Skin 89

CHAPTER FOUR: CONCLUSION AND RECOMMENDATION 90

References 92

Appendices 107