ABSTRACT
The effectiveness of powdered leaves of Imperata cylindrica (spear grass), Sida acuta (wire weed), Chromolaena odorata (siam weed) and Gmelina arborea (Gmelina) at different dosages (0, 2.5, 5.0 and 7.5g) against Sitophilus zeamais infesting stored maize grains was assessed. Treatments were mixed with 100 g of maize grains (landrace, Esa’ ma yewangha), infested with 30 adults S. zeamais and stored in 200 ml glass jars with perforated lids. The setup was maintained under ambient conditions (25 - 300C and 70 - 90% RH) between April and June, 2017. Mortality assessment was at 2, 4 and 6 days after treatment (DAT), after which all adults were sieved out and the setup kept undisturbed for 5 weeks. The trial was laid out in a completely randomized design (CRD) and replicated four times. Analysis of variance showed that Cypermethrin caused significantly higher mortality than the tested plant powders. Cumulative mortality of adult S. zeamais significantly (P ≤ 0.05) increased with increased treatment dosages and durations of storage. There were significantly (P ≤ 0.05) higher mortality in maize grains treated with 7.5 g/100 g of S. acuta (55.00 and 64.17%) and I. cylindrica (53.33 and 60.00%) compared with C. odorata (44.17 and 50.83%) and G. arborea (35.83 and 40.00%), respectively at 4 and 6 DAT. Results also showed that the efficacy of these plant powders on weevil emergence was dose dependent with higher doses providing greater protection of the maize grains. Cypermethrin treated grains had significantly (P ≤ 0.05) lower values than those treated with plant powders in all parameters tested. Significantly (P ≤ 0.05) lower mean progeny emergence (3.0 and 3.5), and grain weight loss (1.1g and 1.30g) was recorded in I. cylindrica and S. acuta, respectively in 7.5g/100g grains compared with (9.3 and 15.0) and (2.9g and 4.3g) in C. odorata and G. arborea, respectively. However, these treatments did not significantly affect seed germination. The insecticidal properties exhibited by these plant powders make them attractive in upgrading traditional post-harvest protection practices. The result of this study can encourage and serve as a possible means of ensuring a steady supply of good quality maize grains.
TABLE
OF CONTENTS
Cover page i
Title page ii
Declaration iii
Certification iv
Dedication v
Acknowledgements vi
Table of Contents vii
List of Tables x
Abstract xi
CHAPTER 1:
INTRODUCTION
1.1 Background of the Study 1
1.2 Statement of the Problem 4
1.3 Justification of the Study 5
1.4 Aim and Objectives of the Study 6
CHAPTER 2:
LITERATURE REVIEW
2.1 Origin and Domestication of Maize 7
2.2 Requirements for Maize
Cultivation 7
2.2.1 Temperature 7
2.2.2 Rainfall 8
2.2.3 Soil 8
2.2.4 Topography 9
2.3
Harvesting and Storage of Maize 9
2.4 Uses and Nutritional Value of
Maize 9
2.5
Constrains of Maize Production 11
2.6 Major
Insect Pests of Stored Maize 12
2.7 Description and Biology of Sitophilus zeamais
Motschulsky 12
2.7.1
Losses and damage caused by S. zeamais 13
2.7.2
Factors affecting development of stored
products pests 14
2.8 Control
of Sitophilus zeamais 16
2.8.1
Cultural control 16
2.8.2
Physical control 16
2.8.3 Biological/biotechnical
control 17
2.8.3.1 Use
of parasites and insect pathogens 18
2.8.3.2 Use
of resistant cultivars 18
2.8.4 Chemical control 20
2.8.4.1 Use
of synthetic insecticides 20
2.8.4.2 Cypermethrin 21
2.8.5
Botanical control 22
2.8.5.1 Imperata cylindrica (spear
grass) 25
2.8.5.2 Sida acuta (wire weed) 25
2.8.5.3 Chromolaena odorata (siam weed) 26
2.8.5.4. Gmelina arborea (Gmelina) 27
CHAPTER 3:
MATERIALS AND METHODS
3.1. Experimental Site 29
3.2 Collection and Preparation of
Botanicals and Insecticide 29
3.2.1 Test plants 29
3.2.2 Synthetic insecticide 29
3.3 Test
Insects and Maize Cultivar 32
3.4 Sexing of Adult Sitophilus zeamais 32
3.5
Infestation Procedure 32
3.6 Tested
End Points Mortality 33
3.7 Progeny Emergence 33
3.8 Damage Assessment 34
3.9 Viability Test 34
3.10 Statistical Analysis 35
CHAPTER
4: RESULTS AND DISCUSSION
CHAPTER
5: CONCLUSION AND RECOMMENDATION
5.1 Conclusions 50
5.2 Recommendations 50
References
Appendices
LIST
OF TABLES
3.1: Botanicals tested, part used and
their Phytochemical constituents 31
4.1: Percentage cumulative mortality
levels of Sitophilus zeamais
treated with four selected plant powders and cypermethrin over
a six day trial 37
4.2: Mean progeny emergence of Sitophilus zeamais in stored maize
grains
treated with four selected plant powders and
cypermethrin at 5WAT 39
4.3: Mean percentage damage of Sitophilus zeamais in stored maize
grains treated
with four selected plant powders and cypermethrin 41
4.4: Weight loss of maize grains treated
with selected plant powders
and cypermethrin 43
4.5: Mean Percentage germination of
maize grains treated with
selected botanical concentrations 45
CHAPTER
1
INTRODUCTION
1.1
BACKGROUND OF THE STUDY
Maize (Zea mays L.) is a major staple crop in the world, belonging to the
family Poaceae. It is one of the most versatile emerging cash crops having
wider adaptability under varied climatic conditions. After wheat and rice,
maize is the third most grown cereal in the world (Lyon, 2000). According to WASDE (2017), the world was projected to
produce 1.04 billion metric tons of maize in 2017 with United States leading
with 384.7 million tons followed by China, 219.5 million tons. In Africa, South
Africa had the highest production with 13 million tons and Nigeria accounted
for 7.2 million tons (WASDE, 2017). The grain is very nutritious, with about
70-72% digestible carbohydrate, 4-4.5% fats and oils and 9.5-11% proteins
(Larger and Hill, 1991).
In Nigeria, maize has the largest
area devoted for cultivation, which has continued to expand because of technological
advancements (Adedire and Lajide, 2003). It occupies less land area than either
wheat or rice but has a greater average yield per unit area of about 5.5 tons
per hectare (Ofori et al., 2004). The crop is grown in many
southern states in Nigeria, for various purposes; including fodder for animals,
and food for man (IITA, 2009).
Increasing
production and productivity of maize has been achieved through the development
of high yielding stress tolerant varieties. Despite this intervention at production
level, there is evidence of food insecurity arising from food storage losses. Storage
losses due to pests threaten livelihoods of farmers across Africa (Kamanula et
al., 2011) with maize weevil (Sitophilus
zeamais) gaining much attention beacuse it attacks both field crops and
stored grains (Haines, 1991).
Sitophilus
zeamais Mots. is serious pest of economic
importance in stored products worldwide. The population dynamics of Sitophilus species is favoured in food
materials that have more than 10% water content (Haines, 1991). Voracious
feeding by S. zeamais on the whole
grain causes weight loss with fungal growth, quality loss through increase in
free fatty acids and it can completely destroy stored grains in all types of
storage systems/facilities (Trematerra et
al., 2007). The grain damage caused, affects both farmers
and traders. S. zeamais larvae are
internal feeders on the maize grains
(CABI, 2012). Internal feeding affects seed viability thus negatively affecting
seed germination where non-hybrid (retained seed) is used for new season
planting.
Different technologies such as environmental
manipulations to hinder growth, maturation and reproduction of storage pests
have been effectively used (Oduor et al.,
2000). Such environmental manipulations have been attained by employing a
number of control measures, including the use of pesticides, cultural and
physical control measures (CABI, 2012, Pereira et al., 2009). Stored crop insect management technologies
among rural communities include the application of chemical pesticides (belonging
to different toxicological classes) that are expensive to buy, unreliable in
terms of time availability and inadequate in handling practices (Rugumamu,
2011). Their use are
often associated with a number of drawbacks (Benhalima et al., 2004) including the occurrence
of resistance in insects, accumulation of residues in food, damage to human
health and also cause negative effects on the non-target organisms,
environmental contamination, besides the increase in production costs (Campos et al., 2013). This problem is acute for
subsistence farmers who produce and store their harvested maize grains locally
often under conditions favorable for insect colonization (Abebe et al.,
2009). Rationally it makes more sense and is economical to safeguard the crop
that has been harvested instead of trying to make up for the losses through
increased production. Most studies that have been conducted have been directed
to growing of crops in the field with limited attention paid to protect the
crop in storage (Derera et al., 1999).
One
alternative to conventional control is the use of plants with insecticidal
properties, whose parts can be prepared and applied as powders, extract, and
oils. The use of more natural and sustainable methods that can offer compatible
control efficacy plus benefit of reduced hazards to the environment is most
favoured (Isman, 2006; Arabi, 2008; Abdelgaleil, 2009). With recent demands for
maize in different homes, there is need to study the various plant species
reported to have medicinal properties in Nigeria and test their potential as
insecticides against maize weevil to provide information for proper handling of
the products. It is against this background that this study was conducted to find
out the efficacy of spear grass (Imperata
cylindrica), wire weed (Sida acuta), Siam weed (Chromolaena
odorata) and Gmelina leaves (Gmelina
arborea) on Sitophilus zeamais in
stored maize grains.
1.2
STATEMENT OF THE PROBLEM
Due to high subsistence grain
production practiced by majority of the world population, damage resulting from
insect infestation especially maize weevil contributes to heavy economic
losses. These losses can be up to 80% of the total production (Fox, 2013), with
insects accounting for 30%–40% (Abass et al., 2014). In Sub-Saharan
Africa, from harvest to consumption of maize, the maize weevil, S. zeamais can attack cereals causing
more than 30% damage which can increase to 90% after five months of storage if
unprotected (Boxall, 1986). In Nigeria, grain production and consumption is
often hampered as a result of post-harvest losses caused by storage pests and
other spoilage agents. Nigeria recorded over 24.9% losses in maize grains,
estimated as 56.7 billion Naira (Deepak and Prasanta, 2017). Damaged grains are
prone to contamination by mycotoxins (Kankolongo et al., 2009). Insect pests are continously gaining advantage in
Nigeria due to favourable climatic conditions as well as poor management and
storage facilities, posing serious problems to agriculture (Ogban et al., 2015).
1.3
JUSTIFICATION OF THE STUDY
Due to increasing pest damage and
resistance to pesticides, environmental and health concerns posed by the use chemical
pesticides, there is need to identify, evaluate and recomend new, available and
benign alternatives for control of S.
zeamais. Plant powders from I.
cylindrica, S. acuta, C. odorata and G.
arborea could serve as alternatives to chemical insecticides which may offer
a new dimension to pest control, moreover, these plant materials are available
in the environment and at no cost to the farmers.
1.4
AIM AND OBJECTIVES OF THE STUDY
i.
To determine the
protectant efficacy of I. cylindrica, S.
acuta, C. odorata and G. arborea for the control S. zeamais in stored maize grains
ii.
To determine the
treatment dosage that will significantly reduce S. zeamais population infesting stored maize grains
iii.
To determine viability of
seeds treated with the botanicals, I.
cylindrica, S. acuta, C. odorata and G. arborea
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