Laboratory studies were conducted to evaluate the insecticidal properties of Dennettia tripetala against maize weevil (Sitophilus zeamais). 100g of maize were weighed into white plastic cups and treated with 0%, 5% and 10% powders of D. tripetala. Parameters considered were mortality and progeny development. The treatment was applied as direct admixture. The results showed significant weevil mortality after 96 hours of exposure compared with the control. Also, significant (P<0.05) adult emergence (466) was observed at 5% while 10% recorded lower (433.4) adult emergence. The mortality at both 5% and 10% could suppress progeny development compared with the control. This study showed that powder of D. tripetala can be used effectively in the management of S. zeamais in post-harvest systems.



Cover page    -    -    -    -    -    -    -    -    i

Certification        -    -    -    -    -    -    -    ii

Dedication    -    -    -    -    -    -    -    -    iii

Acknowledgement        -    -    -    -    -    -    iv

Table of content        -    -    -    -    -    -    v

List of tables    -    -    -    -    -    -    -    vii

Abstract    -    -    -    -    -    -    -    -    viii


1.0    Introduction        -    -    -    -    -    -    1


2.0    Literature review    -    -    -    -    -    -    4

2.1    Laboratory evaluation of different powders from Dennettia tripetala as protectants against pests    -    4

2.2    Uses of plant powders as protectants against damage by storage pest     -    -    -    -    -    -    5

2.3    Uses of plant, extracts and as protectants against damage by storage pest    -    -    -    -    -    -    8

2.4    Uses of plant oils as protectant against damage by storage pest    -    -    -    -    -    -    -   

2.5    Evaluation of insecticidal properties of pepper fruit, Dennettia tripetala against maize weevil Sitophilus zeamais  -    -    13


3.0    Materials and methods    -    -    -    -    -    16

3.1    Culturing of insects    -    -    -    -    -    16

3.2    Source of maize grain    -    -    -    -    -    16

3.3    Source and preparation of plant material     -    -    17

3.4    Laboratory procedure    -    -    -    -    -    17

3.5    Weevil mortality    -    -    -    -    -    -    17

3.6    Progeny development    -    -    -    -    -    18

3.7    Data analysis    -    -    -    -    -    -    18


4.0    Results    -    -    -    -    -    -    -    19

4.1.1    Insect Mortality    -    -    -    -    -    19

4.1.2    Progeny development    -    -    -    -    20

4.2    Discussion    -    -    -    -    -    -    -    21

    4.2.1    Insect mortality    -    -    -    -    -    21

    4.2.2    Progeny development    -    -    -    -    22



5.0    Summary and Conclusion    -    -    -    -    23

References    -    -    -    -    -    -    -    24

Appendices        -    -    -    -    -    -    35



Maize (Zea mays) is an important food in many tropical, sub-tropical and warm temperate countries, including most parts of tropical Africa (Onwueme and Sinha, 1991). It is also used extensively as the main source of calories in animal feeds and feed formulation.

The economic situation in a developing country like Nigeria is adversely affected mostly by post harvest losses of Agricultural products which are usually encountered especially during storage caused by pests and other spoilage agents (Arannilewa et al, 2002).

The overall goal of storage is to ensure food security and agricultural commodities are preserved in storage for the attainment of price stabilization, national and domestic food security, provision of raw materials for industry and international trade, provision for a country’s strategic stock, enhancement of a nations’ international status and provision of seeds, (Lale 2002).

Severe attack by insects is one of the major constraints in profitable production and efficient storage of cereal grains. Sitophilus zeamais is one of the most destructive pest of stored grain and the primary pests of stored maize in the world (Bekele, 2002). This insect has a wide host range with a high capacity to penetrate grain mass and can infest grains in field as well as in storage and accounts for about 50% of loss in stored maize.

Though various synthetic insecticides have been developed over the years for the control of S. zeamais, the cost of purchase, negative environmental impacts of synthetic insecticides including harm on non-target species, insect resistance, high mammalian toxicity and health hazards are some problems of using synthetic insecticides and these have necessitated research interest on the development of alternative control measures preferably botanical insecticides as it is safe and biodegradable.

Plants produce secondary metabolites many of which act as natural defence against insects and disease causing micro organisms (Potenza et al; 2004). Secondary metabolites from plant species have been identified which include alkaloids, terpenoids, flavonoids which can have insecticidal properties, (Vendramim and Castiglioni, 2000; Potenza et al, 2004).

    Dennettia tripetala (pepper fruit) is an indigenous fruit tree of the family Annonaceae (Etukudo, 2000). Dennettia tripetala is a well-known forest fruit and spicy indigenous medicinal plant. It is widely domesticated in the southern, eastern and western parts of Nigeria. A survey of existing literatures shows that pepper fruits contain Dennettia essential oils and phenolic acids (Anyaele and Amusan, 2003), ethanol (Okwu and Morah, 2004), alkaloids (Rossana et al; 2003), ethylacetate, flavonoids, tannis and glycosides.

This study evaluated leaf powder from Dennettia tripetala as stored maize protectant against Sitophilus zeamais.

The objectives were to:

1.    determine the toxicity of D. tripetala leaf powder against S. zeamais

2.    determine the effect of D. tripetala  leaf powder on the progeny development of S. zeamais.



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