CHAPTER ONE

INTRODUCTION

1.0 INSECTICIDES (General Overview)

MOSQUITO:Insecticide is a substance or a mixture of substances used for killing insects[1] . It is well known fact that many protozoal bacteria diseases are transmitted from man to man by insects. One may combat these diseases not only by means of prohylactic drugs but also by the destruction of the insects carriers.

Insecticide is a chemical compound that is lethally toxic to insects either by ingestion or by body contact. It is applied to vegetation, crops and insect breeding areas either as liquid spray or as dry powder[2] .

They are used in agriculture, medicine, industry and household. The use of insecticides is believed to be one of the major factors behind the increase in agricultural productivity in 20th century.

Nearly, all insecticides have the potential to significantly after ecosystem, many are toxic to human and others are concentrated in food chain. It is necessary to balance agricultural needs with environmental and health issues when using insecticides. It is crucially important that all the rural areas in Nigeria are being educated on the need to eradicate insects especially mosquitoes that might breed around the environment and transmit malaria to people living within the enclave.

Integrated Pest Management (IPM) in the home being with restricting the availability of insects of three vital commodities; shelter, water and food. If insects become a problem despite such measures, IPM seeks to control them using the safest possible methods targeting the approach to the particular pest[1] .

Years now, efforts are geared towards controlling malaria infestation both in urban and rural areas. A lot of measures are being taken to reduce the number of death as a result of malaria.

We hear now and then that numbers being quoted by the analyst that died of malaria attack. Thus, free mosquitoes treated nets are always distributed to families and individuals all in a bid to reduce malaria attack from mosquito bite.

In the light of this, it is necessary to study God-given substances in this case, plant that has embedded substances that will help man combat mosquitoes or at least reduce infestation to the barest minimum.

1.1. OBJECTIVES OF THE STUDY/WORK

The purpose of this work is to produce mosquito repellants using orange peels (cestrum) wastes perse, which will save the cost of production and purchase, thereby increasing its availability especially in the rural areas. If the work is successful, production of mosquitoes repellants using orange peels will provide source of employment to our teaming youths and also make mosquito repellant within the reach of everybody, thereby reducing the number of death due to malaria caused by mosquito bite.

1.2. SCOPE OF THE STUDY

Orange peels (cestrum) will be prepared and used for the production of mosquito coil, which ignited, will repel mosquitoes within the limit of the smoke. The produced coil will be tested for the effectiveness performance. Cost analysis should also be taken to know weather mass production will be more effective or not.

1.3. LITERATURE REVIEW

HISTORY ASPECT OF MOSQUITO REPELLENT

Traditionally, various types of substances have been used to repel mosquitoes. These include such things as smoke, plant extracts, oil, tars, muds, etc.

As insects repellants technology became more sophisticated, individual compounds were discovered and isolated. This allows the formulation of new and more efficient forms of mosquito repellants.

The first truly effective active ingredient used in mosquito repellants was citronella oil[3] . This material is a herbal extract derived from the citronella plant, an Asian grass. While citronella has been used for centuries for medical purposes, its repellence was only accidentally discovered in 1901, when it was used as a hairdressing fragrance. Since citronella oil is a fragrant material, it is thought that the chemical terpenes of which it is composed are responsible for its repellant activity.

Citronella oil does repel mosquitoes, but it has certain characteristics which limit its effectiveness. For example, it is very volatile and evaporates so quickly from the surface to which it is applied. Also, large amount are needed to be effective. The disadvantages of using citronella oil prompted researchers to study alternative synthetic compounds many of the early attempt at creating synthetic insect repellants were initiated by the Unites State military. Out of this research, the discovery of the repellant dimethylphthalate in 1929. This material showed a good level of effectiveness against certain insect species, but it was ineffective against others. Indalone was found to repel insect in 1937 and Rutgers 612 (2-ethyl-1,3-hexane diol) was synthesized soon after. Like dimethylpthalate, these materials had certain limitations which prevented their widespread use[3] .

Since none of the available materials were ideal repellents, research into new synthetic materials continued. In 1955, scientists synthesized DEET (n-n-diethyl-netatoluamide) currently the most widely used active ingredient for mosquito repellents.

After its discovery, repellent manufacturers developed many different forms in which to deliver DEET, such as creams, lotions and aerosols[4] .

1.4. CLASSIFICATION OF INSECTICIDE

Insecticides are usually classified into the following three classes.

STOMACH OR INTERNAL INSECTICIDES

These insecticides which are taken up by the insects are called stomach poisons or insecticides. Example, Boric acid.

CONTACT OR EXTERNAL INSECTICIDES

These insecticides destroy the insect simply by external bodily contact. Example Rotenone.

FUMIGANTS

These insecticides act on the insects through the respiratory system. Example hydrogen cyanide, carbon disulphide, nicotine, p-dichlorobenzene, etc. [5] .

Insecticides may be applied as a spray, liquid or in suspension, as a dust or as a gas.

1.5. CHEMICAL INSECTICIDES MAY BE CLASSIFIED AS INORGANIC, NATURAL AND ORGANIC INSECTICIDES.

INORGANIC INSECTICIDES

Before world war II nearly all the insecticides were inorganic compounds of which arsenic, fluorine, sulphur and cyanide compounds were the most important. In recent years, inorganic insecticides have been greatly displaced by organic compounds in many applications.

The major disadvantage of inorganic insecticides is their comparable toxicity to man and other warm blooded animals. Upon handling and so as residues on food products[6] .

SOME INORGANIC INSECTICIDES ARE;

Lead Arsenate
Calcium Arsenate
Paris green
Flourine compounds
Sulphur and sulphur compounds
Hydrocyanide acid[6]

NATURAL OR PLANT INSECTICIDES

Plant materials yield some of the most widely used insecticides and many of them are being supplemented by the synthetic organic insecticides. The roots stem, leaves or flowers may be finely grounded and used as such or active parts may be extracted and used either alone or with other toxicants and auxiliary materials.

SOME NATURAL INSECTICIDES ARE

Nicotine
Rotenone
Allethrin
Pyrethrins[6]

ORGANIC INSECTICIDES

A typical organic insecticide is DDT (Dichlor-Diphenyl-Trichloroethane) with IUPAC name 4,4-(2,2,2-trichloroethane-1,1-diyl)bis chlorobenzene.