TABLE OF CONTENTS
Cover page ————————————————————————- i
Title page ————————————————————————- ii
Certification ————————————————————————- iii
Dedication ————————————————————————- iv
Acknowledgement —————————————————————- v
List of tables ————————————————————————- viii
Abstract ————————————————————————- ix
CHAPTER ONE
1.0 Introduction ————————————————————————— 1
CHAPTER TWO
2.0 Literature review ———————————————————— 3
2.1 The cowpea weevil (Callosobruchus maculatus (Fabricus))
—————— 3
2.1.2 Genetics ———————————————————————– 3
2.1.3 History and distribution ———————————————————- 3
2.1.4 Biology and ecology ———————————————————- 4
2.2 Control methods —————————————————————— 6
2.2.1 Chemical control ————————————————————— 6
2.2.2 Traditional pest control —————————————————— 7
2.2.3 Modern biological pest control methods ———————————– 8
2.2.4 Plant materials —————————————————————- 8
2.2.5 Musa balbisiana (Banana) ————————————————– 8
2.2.6 Cow dung —————————————————————————- 9
2.2.7 Phaseolus vulgaris (common bean) ——————————————– 10
2.2.8 Ocimum spp ———————————————————————- 11
2.3 Gmelina arborea (Robx.) ———————————————————– 13
2.3.1 Taxonomy of Gmelina arborea ———————————————— 13
2.3.2 Description —————————————————————- 14
2.3.3 Ecology ——————————————————————- 14
2.3.4 Cultivation ——————————————————————- 15
2.3.5 Insecticidal uses of G. arborea ————————————— 16
CHAPTER THREE: MATERIALS AND METHODS
3.1 Experimental Location ————————————————– 17
3.2 Source of grains —————————————————– 17
3.3 Gmelina arborea seed powder preparation ————————- 17
3.4 Experimental design and procedure ———————————— 18
3.5 Data collection ———————————————————– 18
3.5.1 Temperature and humidity readings ——————————————– 19
3.5.2 Number of live beetles ———————————————- 19
3.5.3 Number of dead beetles ————————————————— 20
3.5.4 Number of punctures per grain —————————————— 20
3.5.5 Total number of grains ————————————————– 20
3.5.6 Weight loss ————————————————————— 20
3.5.7 Oviposition ————————————————————— 20
3.6 Data analysis —————————————————————- 21
CHAPTER FOUR: RESULTS
4.1 Mortality of C. maculatus ——————————————————— 22
4.2 Oviposition of C. maculatus ——————————————————- 22
4.3 Emergence of F1. Progeny of C. maculatus —————————————
22
4.4 Percentage grain damage ——————————————————— 23
4.5 Percentage weight loss ————————————————————– 23
CHAPTER FIVE: DISCUSSION, CONCLUSION AND RECOMMENDATION
5.1 Discussion ———————————————————————- 25
5.2 Conclusion and Recommendation —————————————— 27
REFERENCES ——————————————————————– 28
LIST OF TABLES
Table 1: Percentage mortality, oviposition, emergence of
adult C. maculatus, grain damage and weight loss as influenced by seed powder
of G. arborea. —————————— 24
ABSTRACT
One of the most important global problems is protecting
storage crops from destructive storage insect pests. For the control of
insects, synthetic chemicals are continuously used, and their toxicity
endangers health of farm operators, animals and food consumers. The negative
effects on human health led to a resurgence of interest in botanical
insecticides due to their minimal costs and ecological side effects. In view of
this, the efficacy of Gmelina arborea seed powder on the control of
Callosobruchus maculatus (F.) on cowpea grains was conducted in the laboratory
of the Department of Crop Science, Faculty of Agriculture, University of Benin,
Benin City, Nigeria. The study involved five rates (0, 5, 10, 15, and 20g) of
G. arborea seed powder laid out in a completely randomized design with four
replications. Data were collected on adult mortality, oviposition, adult
emergence of C. maculatus, percentage damaged grains and weight loss. The seed
powder of G. arborea had significant effect on mortality, oviposition, adult
weevil emergence, grain damage and weight loss. Seed powder application rate of
20 g completely suppressed weevil infestation. From the results of the study,
it is thereby suggested that 5 g treatment of seed powder of G. arborea can be
used for the effective control of C. maculatus per 20 g of cowpea (vigna
unguiculata).
CHAPTER 1
INTRODUCTION
Cowpea (Vigna unguiculata (W.) is one of the five most
important legumes in the tropics and provides the protein for most people in
the region and enriches the soil with nitrogen through symbiosis by rhizobium
(Duke, 1990). It originated and domesticated in Southern Africa and later
spread to East, West Africa and Asia (AGRONIGERIA, 2015). It is an important
alternative source to expensive animal protein (Ileke et al., 2013) as it
provides food and animal feed for human and livestock in Africa, Asia, Europe,
United States, Central and South America.Many insect pests have been reported
attacking cowpea both in the field and in storage among which is the cowpea
seed beetle (Adebayo et al., 2013). The cowpea seed beetle, Callosobruchus
maculatus (Fab.), is the most important storage pest of cowpea throughout the
tropics (NRI, 1996) belonging to the family Chrysomelidae (Kergoat et al.,
2007).
They multiply rapidly under condusive conditions in storage,
giving rise to a new generation every month in grain. They riddled cowpea seeds
with adult exit holes and defaced with egg covers which leads to reduced
weight, poor food value and low seed viability (Ofuya, 2003). Females are
darker overall, while males are brown. The plate covering the end of the
abdomen is large and dark in colour along the sides in females, and smaller
without the dark areas in male (Beck and Blummer, 2009). The larvae of this
species feed and develop exclusively on the seed of legumes (Fabaceae) hence
the name bean beetle.
In Africa, most of our agricultural produce is produced by
poor resource farmers who cannot easily afford the cost of safer synthetic
pesticides. In many systems utilizing chemical pesticides, resistance is the
rule rather than the exception; operator hazards are very real; environmental
and consumer concerns cannot be ignored; and the proponents of integrated pest
management (IPM) have to be taken seriously in order to develop sustainable
systems for protecting stored products against pest infestation (Haines, 2000).
It has therefore become necessary to search for other alternatives such as
inert dusts and botanical insecticides, which are environmentally friendly and
cost effective at the small-scale farmer level (Bekele et al., 1997)
Researches have shown that botanicals have been extensively
used on agricultural pests and to very limited extent on insect pests of stored
products (Ufele et al., 2013) There is a possibility of using extracts from
some plants to control mycelial growth as well as conidial germination of C.
gloeosporiodes (Enobakhare, D. A. et al., 2007). Hence, this present study was
undertaken to evaluate the insecticidal potentials of Gmelina arborea (L) seed
powder in the control of cowpea beetle (C. maculatus (F.).