ABSTRACT
Studies were carried out at Nsukka to evaluate maize varieties and accessions for resistance to insect pests and toxicity of Ordeal bark solvent extracts to Sitophilus zeamais Motsch. The studies were carried out in Departments of Crop Science, Civil, Agricultural and Bioresources Engineering, University of Nigeria, Nsukka (UNN). The proximate and phytochemical analyses for all maize accessions were carried out in the Department of Food Science and Technology Laboratory of Ahmadu Bello University (ABU) Zaria in collaboration with International Institute of Tropical Agriculture (IITA), Ibadan. A total of twenty-one maize accessions were used, which included (a) three local landraces (Nsukka-pink, Enugu-Ezike and Kagoro white from locations as their names imply, (b) two hybrids (Sammaz -15 and 16) and (c) sixteen open pollinated varieties (Sammaz -11, 14, 17, 18, 20, 26, 27, 28, 29, 31, 32, 33, 34, 35, 37, and Oba Super 2). Both hybrids and open pollinated varieties were obtained from Institute of Agricultural Research (IAR) Samaru Zaria in collaboration with International Institute for Tropical Agriculture (IITA), Ibadan. The results indicated that the various maize accessions differed significantly in their relative susceptibility to S. zeamais damage. Sammaz -35 with susceptibility index (SI) of 5.33 was moderately susceptible (MS), Sammaz -26 (SI = 3.47) moderately resistant (MR), while Sammaz -32 (SI = 1.79) was resistant (R) to maize weevil damage. Proximate analysis showed that Sammaz- 27, 32, 34, 35, 17 and 18 contained significantly (p<0.05) higher moisture (3.84 %), fat (4.18 %), ash (2.04 %), protein (8.76 %), carbohydrate (85.36 %) and fibre (1.12 %), respectively compared to other varieties and accessions. Lectin content of 0.006 mg/100 g maize was present in each of Sammaz- 14, 18 and 29 and were significantly (p<0.05) higher than those of other varieties and accessions. Sammaz -11, 37, 15 and 27 were significantly (p<0.05) higher in phytate (0.072 mg/100 g maize), oxalate (0.70 mg / 100 g maize), tannin (0.48 mg/ 100 g maize) and trypsin inhibitor (0.06 mg/ 100 g maize) contents, respectively relative to other accessions. Irrespective of year of planting, stemborer damage on maize stalks were significantly (p<0.05) higher in July than in May planting. Sammaz -32 sustained higher borer damage relative to other varieties and accessions. Conversely, Sammaz- 28 harboured significantly (p<0.05) more earworm populations than other varieties / accessions, year and season of planting, notwithstanding. The organic solvents (n-hexane and petroleum-ether) extracts of ordeal tree stembark caused 100 % adult weevil mortality, F1 and F2 suppression, and offered complete protection against grain damage and weight loss caused by maize grain weevil. On the other hand, the organic solvents caused complete loss of viability of seeds in all accessions. The path coefficient analyses revealed that the highest direct negative effects on susceptibility were exhibited by % tannin (-0.4127), fat (-0.3698), grain width (GW) (-0.7332), extension (-0.7018) and compressive strength (CS) (-0.8282). The highest direct positive effect on cob weight (CW) was observed in grain weight (GW) (0.7301) while the highest negative direct effect on cob weight (CW) was observed in percentage infestation (PI) (-0.37745) of stem borers.
TABLE OF CONTENTS
Cover page – – – – – – – – – – i
Declaration – – – – – – – – – – ii
Approval Page – – – – – – – – – iii
Certification Page – – – – – – – – – iv
Dedication – – – – – – – – – – v
Acknowledgments – – – – – – – – – vi
Table of Content – – – – – – – – – viii
List of Tables – – – – – – – – – – xiii
List of Figures – – – – – – – – – xvii
List of Plates – – – – – – – – – – xviii
Abstract – – – – – – – – – – xx
INTRODUCTION – – – – – – – – – 1
Objectives – – – – – – – – – – 2
LITERATURE REVIEW – – – – – – – 3
Maize Taxonomy, Age, Origin, Distribution and Production – – – – 3
Trends of maize production in Nigeria- – – – – – – 5
The cornbelt of Nigeria – – – – – – – – – 5
Causes of post-harvest losses in maize – – – – – – – 10
Ways of reducing post-harvest food losses in maize – – – – – 11
Susceptibility of maize grains to storage pest – – – – – – 12
Sources of storage insect pest infestation – – – – – – – 12
Nature of damage or loss on maize caused by storage insect pests – – – 13
Quantity of storage losses of maize by pest in the tropics – – – – 13
Biochemical composition of maize – – – – – – – – 14
Anti-nutrient in cereal grain – – – – – – – – – 14
Positive effects of phytochemicals in human health and nutrition – – – 15
Use of plant materials for insect pest control in storage – – – – 18
Use of plant oils, liquid and powdery extracts in insect pest control in storage – 21
Ordeal tree (Erythrophleum africanum Harms) – – – – – 23
Corn stalk borers – – – – – – – – – – 26
Biology and ecology of the African maize stalk borer (Buseola fusca, Fuller) – 27
Maize Earworms – – – – – – – – – – 28
Genetics and biochemistry of insect resistance in maize – – – – – 28
Maize-insect tritrophic interactions – – – – – – – – 30
Transgenic corn borer and corn rootworm resistant maize varieties – – – 31
Transgenic avidin maize – – – – – – – – – 31
Advantages and Disadvantages of using Bt-Hybrids – – – – – 32
Mean and standard deviation of data – – – – – – – 34
Standard Deviation – – – – – – – – – 35
Correlation Matrix – – – – – – – – – 35
Path analysis, path diagrams and path tracing rules – – – – – 36
Seed science and seed germination test – – – – – – – 39
MATERIALS AND METHODS – – – – – – – 41
Field screening of maize accessions for stalk borer Resistance – – – 41
Meteorological data collection – – – – – – – – 43
Assessment of maize stem borers attack – – – – – – – 43
Screening test for maize seed / grain susceptibility / resistance to maize weevil
damage – – – – – – – – – – 47
Pre-laboratory Screening Germination Test – – – – – – – 48
Screening of maize varieties / accessions for susceptibility / Resistance to S.zeamais – 48
Biochemical analysis of ordeal tree stembark – – – – – – 51
Effect of Ordeal tree stem bark extracts and Resistance/susceptibility
of the maize Accessions / varieties on the Infestation of S. zeamais – – 51
Evaluation of solvent extracts of Ordeal tree stem bark and synthetic insecticide on
mortality of adult S. zeamais infesting resistant / susceptible
maize varieties – – – – – – – – – 52
Evaluation of solvent extracts of Ordeal tree stem bark and synthetic insecticide on
progeny emergence of S. zeamais on resistant / susceptible stored maize
varities / accessions – – – – – – – – 53
Evaluation of solvent extracts of Ordeal tree stem bark and synthetic insecticide on
grain damage and weight loss caused by S. zeamais to resistant / susceptible
of stored maize varieties / accessions – – – – – – 53
Evaluation of solvent extracts of Ordeal tree stem bark and synthetic insecticide on
germination of resistant / susceptible of stored maize varieties / accesstions – 53
Evaluation of solvent extracts of Ordeal tree stem bark and synthetic insecticide
shelf life / longetivity for 4 weeks against insect pest of stored maize. – 54
Determination of the Physical and Mechanical properties responsible for Resistance /
Susceptiblity to S.zeamais– – – – – – – – 54
Determination of the proximate composition of the maize accessions/varieties – 56
Some maize anti-nutrients and their determination – – – – – 61
RESULTS – – – – – – – – – – – 64
Meteorological data: Monthly mean rainfall, temperature and relative humidity for
2012 and 2013 cropping seasons – – – – – – – 64
Effect of two planting dates on incidence of stalk borers, earworms on yield
parameters of maize varieties / accessions in 2012 and 2013 cropping seasons – 66
Comparison of effects of month of planting and year on stalk borer, earworm
infestations and yield parameters of maize – – – – – 71
The effect of interaction of planting dates on stalk borer / earworm infestations on
yield parameters of maize accessions / varieties in 2012 and 2013 cropping
seasons – – – – – – – – – – 73
Combined effect of planting dates, stalk borer / earworm infestation on yield
parameters of maize varieties / accessions in 2012 and 2013 cropping
seasons – – – – – – – – – – 81
Comparison of month of planting, stem borer / earworm infestation and yield
Parameters of maize accessions / varieties in 2012 and 2013 cropping seasons – 85
Comparison of month of planting, stem borer / earworm infestation and yield
parameters of maize accessions / varieties in 2012 and 2013 cropping seasons – 87
Screening maize accessions / varieties for susceptibility to Sitophilus zeamais Mot.
infestation – – – – – – – – – – 92
Correlation matrix of susceptibility index and weevil adult mortality, adult emergence,
50% adult emergence time of S. zeamais, % damage and % weight loss of
maize grains – – – – – – – – – – 94
Direct and indirect effect of S. zeamais performance on susceptibility index (SI) of
maize varieties – – – – – – – – – – 96
Physical attributes of maize accessions / varieties and their respective susceptibility
indices to S. zeamais – – – – – – – – – 99
The correlation coefficient of five physical characters evaluated for twenty accessions
/ varieties of maize – – – – – – – – – 101
Path coefficient analysis of six physical properties of twenty maize accessions /
varieties and their direct and indirect effects on maize susceptibility index
to S. zeamais – – – – – – – – – – 103
Cluster analysis of the physical attributes of screened maize accessions / varieties – 107
Effect of mechanical attributes of maize accessions/varieties on their susceptibility
To S. zeamais – – – – – – – – – – 109
The correlation efficient of eight mechanical properties of maize and its susceptibility
to maize weevil (S. zeamais) – – – – – – – – 112
Path coefficient analysis of susceptibility index of 8 mechanical properties of maize
accessions / varieties to S. zeamais – – – – – – – 114
Cluster analysis of the mechanical attributes of screened maize accessions / varieties – 119
Proximate composition of different accessions / varieties of maize – – – 121
Correlation matrix of susceptibility index of maize to S .zeamais and proximate
qualities – – – – – – – – – – 123
Direct and indirect effects of the proximate contents of maize on its susceptibility
index (SI) to S. zeamais – – – – – – – – 125
Anti-nutrients composition (mg / 100 g) of different maize accessions / varieties – 128
Correlation matrix of susceptibility index of S. zeamais infestation on maize and
anti-nutrient effects – – – – – – – – – 130
Path Coefficient analysis of correlation matrix of susceptibility index of S. zeamais
infestation on anti-nutrient components in maize – – – – – 132
Biochemical analysis of ordeal tree (Erythrophelum africanum Harms) stem bark – 135
Biochemical analysis of two stalks of maize varieties (Sammaz-14 and 28) adjudged
to be moderately resistant (R) and moderately susceptible (MS) respectively – 136
Effect of solvent extracts concentrations of ordeal tree stem bark on mortality of
adult S. zeamais 24, 48, 72 hrs and 7th day post-treatment – – – – 137
Progenies (F1 and F2) adult emergence of S. zeamais on susceptibility status of maize- 143
Effects of solvent extracts concentrations of Ordeal tree stem bark on percentage
damage caused by S. zeamais on susceptibility status of maize – – – 146
Effects of solvent extracts concentrations of ordeal tree stem bark on percentage
weight loss caused by S. zeamais on susceptibility status of maize – – 148
Effects of ordeal tree stem bark extraction solvent concentrations shelf life /
longevity at weekly intervals on adult mortality of S. zeamais 24, 48, 72 hours
and 7th day after exposure to the extract – – – – – 150
Effects of ordeal tree stem bark extraction solvent concentrations shelf life /
longevity at weekly intervals on adult F1 and F2 emergence of
- S. zeamais after treatment – – – – – – – 156
Effects of ordeal tree stem bark extraction solvent concentrations shelf life /
longevity at weekly intervals on percentage grain damage by S. zeamais
post-treatment – – – – – – – – – 160
Effect of ordeal tree stem bark extraction solvent concentrations shelf life /
longevity at weekly intervals on germination weight loss of maize grains
caused by S. zeamais after treatment. – – – – – – 162
Effects of ordeal tree stem bark extraction solvent concentrations shelf life /
longevity at weekly intervals on percentage seed germination count
after treatment – – – – – – – – – 164
Correlation matrix of yield parameters of maize infested by stalk borers and
earworms in May 2012 and 2013 cropping seasons – – – – – 166
Path analysis of direct and indirect effects of yield parameters of maize infested by
stalk borers and earworms in May 2012 and 2013 cropping seasons – – 168
Cluster analysis of maize accessions / varieties with similarities in yield parameters
affected by maize stem borers and earworms infestation in May 2012 and 2013
cropping seasons – – – – – – – – 173
correlation matrix of stem borers and earworms factors on yield of maize in
May 2012 and 2013 cropping seasons – – – – – – 175
Path analysis of stem borer and earworms activity factors on yield of maize in
May 2012 and 2013 cropping seasons – – – – – – 177
Mean and standard deviations of some maize stalk borer and earworm activity effects
used in the classification of twenty-one accessions/varieties of maize into four
clusters for May 2012 and 2013 cropping seasons – – – – – 182
Correlation matrix of some crop parameters affecting yield under natural infestations
by stalk borers and earworms in July 2012 and 2013 cropping seasons – 184
Direct and indirect effects of maize stalk borers and earworms infestation on
parameters of maize planted in July 2012 and 2013 cropping seasons – – 186
Mean and standard deviations of some maize parameters, similarities and effects
used in the classification of twenty-one accessions / varieties into four clusters
for July 2013 and 2013 cropping seasons – – – – – 191
Correlation matrix of nine insect pests activity factors on maize yield, under natural
infestations by stalk borers and earworm for July 2012 and 2013
cropping seasons – – – – – – – – 193
Path coefficient analysis of eight insect pests activity factors on maize yield under
natural Infestations by stalk borers and earworms in July 2012 and 2013
cropping seasons. – – – – – – – – 195
Cluster analysis of maize stalk borer and earworm effects on twenty-one
accessions / varieties grouped into cluster for July 2012 and 2013
cropping seasons – – – – – – – – 201
DISCUSSION – – – – – – – – – 203
Experiment 1: Screening maize accessions / varieties for Susceptibility / Resistance
to S. zeamaisAttack under laboratory conditions – – – – 203
Experiment 2: Physical attributes of maize accessions / varieties and effects on
maize grain Resistance to S. zeamais – – – – – – 204
Experiment 3: Mechanical attributes of maize accessions / varieties and effects on
maize grain Resistance to S. zeamais – – – – – – – 205
Experiment 4: Evaluation of the proximate compositions of maize accessions /
varieties and Maize grain Susceptibility /Resistance to S. zeamais attack – 205
Experiment 5: Evaluation of anti-nutrients of maize accessions / varieties and
grain Susceptibility / resistance to S. zeamais attack – – – – 206
Experiment 6: Evaluation of the efficacy and shelf-life/longevity of solvent
extracts of Ordeal tree stem bark and maize grain degree of resistance against
- zeamais attack – – – – – – – – 207
Experiment 7: Correlation and path coefficient analysis of crop parameters
affecting maize yield under natural infestations by stalk borers and earworms
in July 2012 and 2013 cropping seasons – – – – – 209
Experiment 8: The correlation and path analysis of stalk borers and earworms
activity factors on yield of maize in May and July 2012 and 2013
cropping seasons – – – – – – – – – 209
CONCLUSION AND RECOMMENDATION – – – – 211
REFERENCES – – – – – – – – – 212
PLATES – – – – – – — – – – 230
CHAPTER ONE
INTRODUCTION
Maize (Zea mays L.) is the most important crop in sub-Saharan Africa (IITA, 2009; Anon., 2011). It is a staple food for an estimated 50 % of the population. It is an important source of carbohydrate, protein, iron, vitamin B and minerals. Africans consume maize in a number of ways (porridges, pastes and drinks). Green maize, fresh on the cob, is eaten baked, roasted or boiled. Every part of the maize crop has economic value. The grain, leaves, stalk, tassel, and cob can all be used to produce a large variety of food and non-food products. In sub-Saharan Africa, maize is mostly grown by small-scale farmers, generally for subsistence as part of mixed agricultural systems (Anon., 2012; IITA, 2009). The United States of America (USA) is the largest world producer of the crop. Other leading producers include Europe, Asia and Latin America (Philip et al., 2006).
Maize has been the diet of Nigerians for centuries. It started as a subsistence crop and has gradually become more important. In Nigeria, maize has now risen to a commercial crop on which many agro-based industries depend on as raw material (Anon., 2012). Lale (1995) reported that more than 200 species of insects have been recorded as damaging the maize plant world-wide and that the insect pest of the genus Sitophilus in the family Curculionidae contains three of the world’s most destructive pests of stored cereal grains, of which two occur in the tropics. The tropical species attacking stored cereals ( maize, rice, sorghum, millet and wheat) are Sitophilus zeamais and Sitophilus oryzae. Their temperate counterpart is Sitophilus granarius. Maribet and Aurea (2008) reported that in stored maize, heavy infestation by S. zeamais may cause weight losses of as much as 30 – 40 %, although losses are commonly 4 – 5 %. Stemborers are the most important insect pest of maize in sub-Saharan Africa causing a yield loss that vary between 20 and 70 % in the field (Ajala et al., 2001), while Gabrielle et al. (2010) attributed a yield loss as high as 40 % only to Busseola fusca. The Anon. (2011) attributed a yield loss of 20 to 40 % to stermborers. The most important are the African maize stalkborer (Buseola fusca) and the spotted stemborer (Chilo partellus). The pink stalkborer (Sesamia calamistis and the sugarcane stalkborer Eldana saccharina) are of minor importance (Schulthess and Ajala, 1999). Beside, the insecticides most commonly recommended for use by farmers against insect pests include plant materials (such as powders, oils and liquid extracts) which have been tested by experts and proven to be effective in the control of insect pests of stored produce and products as well as field maize in Africa (Mbah, 1990).
Increased demands for clean, safe food supplies on one hand, and the problems associated with expensive chemical control of insects on the other hand have stimulated a search for alternative pest control measures. The financial loss as well as complete loss of propagative seeds especially in the remote areas of the third world due to the attack of insect pests on the world’s cultivated crops, especially maize is unbelievably high. Among the growers of maize however, there has been an increasing consciousness of the vital need of protecting their produce, resulting in a high consumption of insecticides. There has been much progress in the search for biologically active plants and inert materials to replace arsenicals, lead, organic chlorine, silicaflouride insecticides, and so on. Although, the synthetic insecticides are very effective for their particular purposes, yet, they are environmentally unfriendly. They also possess the serious disadvantages of being toxic to man, domestic and wild-life, non-target insects, useful plants, and enhancing the potential for the development of pesticide resistance (Ofuya and Lale, 2001; Amadioha, 2004 and Abba, 2005). Synthesized inorganic insecticides exhibit undesirable characteristics that include:
- Seed viability or germination may be impeded with the use of chemical insecticides due to wrong dosage application and length of time of exposure to chemicals, eg. Fumigants may kill the seed embryo if the seeds are exposed to it for too long.
- The soaring cost of the conventional insecticides often caused by scarcity and irregular supply.
- Persistence of chemicals, resulting from their insolubility and eventual adsorption to the soil colloids may be toxic to non-target organisms.
- Some insecticides such as actellic dust have the undesirable quality of deposition of toxic residues. There is also the risk of drift and environmental pollution.
- Possession of single active ingredients, which achieve rapid results but have the high risk of the development of resistance by insect pests.
Objectives of the Study
- To identify maize varieties / accessions with some levels of resistance to stalkborer, earworm and grain weevil (Sitophilus zeamais).
- To determine physical, mechanical and biochemical bases for the susceptibility/resistance of some maize varieties /accessions to stalkborers, earworms and grain weevils.
- To determine the efficacy of solvent extracts of Erythrophluem africanum Harms (Ordeal tree ) in the control of zeamais attack on maize grains.
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