CHAPTER
ONE
INTRODUCTION
1.0 INSECTICIDES (General Overview)
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
1.3.1 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].
1.3.2 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.
1.3.3 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.
DDT
(Dichloro-Diphenyl-Trichloroethane)[1]
DDT
was first prepared by O. Zeidler, a German Ph.D. student in 1874. Its insecticidal
properties were however discovered by a Swiss chemist Paul Muller in 1939. DDT
kills lice and mosquitoes which carries germs of typhus and malaria fever
respectively. DDT was the first chemical to have the property of killing
insects only by means of contact. DDT is still the backbone of many insects
control programs and is widely used as a household insecticide against leaf
hoppers and potatoes and in cotton insect control. DDT is a remarkable powerful
and persistent insecticide that is soluble in kerosene oil, petrol and ethyl
alcohol but insoluble in water. DDT is manufactured by exothermic condensation
of chlorobenzene with chloral at about 300C in the presence of oleum
or 99% sulphuric acid.
DDT
(Dichloro Diphenyl Tdrichloroethane) Fig II [1]
In the 1940s, the properties of the new
insecticide DDT seemed close to miraculous. In tropic, DDT save millions of
lives by killing the mosquitoes that spread malaria, increase crop yields
resulting from DDT’s destruction of insects pests saved million or more from
starvation
DDT and other substances that undergo
biological manifestation have two properties that makes them dangerous;
§ They
do not readily break down into harmless substances
§ They
are fat soluble but not water soluble, therefore, they accumulate in the bodies
of animals particularly in the fat, rather than being broken down and excreted
in the watery urine. Because the transfer of energy from lower to higher tropic
level is extremely inefficient, herbivores must eat large quantities of plant materials
(which may have been spread with DDT), carnivores must eat many herbivores and
so on.
In1951,
the first DDT resistant strains of mosquitoes were reported from Greece, Panama
and U. S. A. In many parts of the world, spraying no longer prevents
transmission of malaria. In addition, the passage of persistent insecticides
such as DDT though the food chain become an increasing problem to birds and
mammals at the top of chain[4].
1.3.4 BIOLOGICAL INSECTICIDES
Recent
efforts to reduce bread spectrum toxins added to environment have brought
biological insecticides back to vogue. An example is the development and
increase in use of Bacillus thuringieness, a bacterial disease of Lepidopterans
and some other insects. It is used as a lavicide against a wide variety of caterpillars.
Because it has little effect on other organism. It is considered more
environmentally friendly than synthetic insecticides. The toxin forms.
Baccillus Thuringiensis. Baccillus Thuringiensis. Toxin has been incorporated
directly into plants through the use of genetic engineering[7].
1.3.5 TOXIC EFFECT OF REPELLENT
Some
insecticide kill or harm other creatures in addition to those they are intended
to kill. For example, birds may be poisoned when they eat food that was freshly
sprayed with insecticides or when they mistakes insecticides granules on the
ground for food and eat them.
Sprayed
insecticides may drift the area to which it is applied into wildlife areas,
especially when sprayed aerially[4].
DDT
can be a threat to health or the environment when used under wrong conditions.
It causes progressively higher concentration in the body of the animal farther
up the food chain.
Biological
parameters were used to evaluate the toxic effect of different brands of
mosquito coil smoke in experimental rats. The smoke from the coil produced
significant increase (P<0.05) in the level of total protein, total albumen,
bilirubin and blood/urea nitrogen when animals were exposed to smoke for 14
days[7].
Similarly,
the smoke from the coils also cause an elevation in the activities of aspirate
amino transference and alanine amino transference. Although the smoke from the
coil did not produce lesions in hearts, lungs and liver examined, the increase
in liver enzyme activities could be due to early liver damage[8].
Epidemiological
studies have shown that long-term exposure to mosquito coil smoke can induce
asthma and persistent wheeze in children. These studies also shows that one
burning mosquito coil produces the same amount of particulate mass (diameter up
to 2.5nm) as 75-137 burning cigarette would, and the coil can be as high as
that released from 51 burning cigarettes[8].
1.4
MOSQUITO
COIL
Mosquito
coil is a mosquito repelling incense usually shaped into a spiral and typically
made from a dried paste of pyrethrum powder. Mosquito coils are widely used as
mosquito repellants. The major active ingredients of mosquito coilsare
purethrins accounting for about 0.3 – 0.4% of the coil mass. When a mosquito
coil is burnt, the insecticides evaporates (pyrethrin, PAH, aldehyde, etc) with
smoke, which prevent the mosquito from entering the room and harm those already
in the room. The remaining components of mosquito coils include filters,
binders, dyes and other additives capable of burning well without flame. He
components generates large amunt of submicrometer particles and gaseous
pollutants such as acenephthene, paranthrene, etc.
Mosquito coils are often used
overnight in sleeping quarters where continous exposures may occur. Chronic
exposure to coil smokes occur during rainy periods because mosquitoes are found
to be more active in the environment due to collection of water and increase in
green plants[9].
1.4.1 HOW
MOSQUITO COILS WORK
Mosquito
coils are burned on specially designed stands placed inside more attractive
looking mosquito coils holders which contain holes to let the smoke out. The
holders can usually be hung up or laid flat. Each mosquito coil slowly burns
for around 8 hours, during which time repelling active ingredients such as
pyrethoids or pyrethrum disperse with the smoke. The combination of ingredients
in the smoke coil either prevents mosquitoes from entering the surrounding
area, encourages them to leave the area if they have not already done so, or
knocks the insect down and kills the[10].
1.4.2 HOW
TO USE MOSQUITO COILS
Mosquito
coils are particularly useful for protection against mosquitoes when sitting
outside at night. They can be placed on a table so people can congregate around
them. It helps to stay in the vicinity of the smoke given off, but this may be
difficult if the smoke is carried away by the wind. A good tip is to place a
mosquito coil down on the ground by people’s ankle and feet, as this is an area
mosquitoes seem to bite frequently.
Again, the less wind there is, the
more likely the mosquito coil smoke will have a chance to be effective.
Mosquito coils are generally meant for use outdoors, but if they have to be
used indoors, it is wise to make sure rooms are well ventilated. Packs of
multiple mosquito coils are available with a coil stand included[10].
1.4.3 ADVANTAGES
OF USING A MOSQUITO COIL
Mosquito
coils nowadays burn without flame for up to eight hours of continuous repelling
action. In quantitative tests, they provide about 80% protection. Mosquito
coils are also cheep and need no special equipment to use it in other than just
lighting it up. They are portable and fit into normal household practices of
lighting candles or incense[11].
1.4.4 DISADVANTAGES
OF USING MOSQUITO COILS
There are several hazards that we know
to be caused by mosquito coils. In 1999, sparks from mosquito coils ignited a
fire that swept through a three-story dormitory building at a summer camp, 23
persons including 19 children died in the blaze in South Korea[12].
The long-term exposure calls for
concerns on the potential toxicological effects of smoke on humans[8].
1.4.5 ACTIVE INGREDIENTS IN MOSQUITO COIL
The
active ingredients found in mosquito coils can be some of the following;
o
PYRETHRUM
(Natural,
powdered material from a kind of chrysanthernum plant, performing moderated)
o
PYRETHRINS
(Extract
of insecticidal chemicals in pyrethrum)
o
ALLETHRIN
Some
times d-trans-alletrin)
(The first synthetic
pyrethrin)
o
ESOBIOTHRIN
(a
form of allethrin)
o
DIBUTYL
HYDROXYL TOLUENE (BHT) (an optional additive to prevent
pyrethroid from oxidizing during burning).
o
PIPERONYL
BUTOXIDE (PBO) (an optional additive to improve the
effectiveness of pyrethroid)
o
N-(2-ethylexyl)-bicyclo-(2,2,1)hept-5-ene-2,3-dicarboximide
(MGK 264) (an optional additive, to improve effectiveness of a pyrethroid)[13].
1.5
CITRUS
SINENSIS/ORANGE PLANT
The
orange plant is a hybrid of ancient cultivated origin, possibly between Pomelo
(citrus maxima) and tangerine (citrus reticulate). It is small
flavouring tree growing to about 10m tall with evergreen leaves, which are
arranged alternatively, of ovate shape with crenulate margins and 4-10cm long.
The orange fruit is a hesperidium, a type of berry[14].
Orange
originated in southeast Asia. The fruit of Citrus
sinensis is called sweet orange to distinguish it from citrus aurantium, the
bitter orange. The name is thought to ultimately derived from the sanskirt, for
the orange tree, with its final form developing languages. In a number of languages.
In a
number of language,it is known as a “Chinese apple” (e.g Dutch Sinaasappel,
“China’s apple”.)[15].
Orange
can be found in almost all parts of Nigeria.
SPECIES OF CESTRUM
The orange peels (cestrum) is gotten
from sweet orange (ctrus sinensis)
1.5.1 IDENTIFICATION
Botanical name Citrus
Sinensis
English name Sweet Orange
Common name` Oroma (Igbo)
Family Rutaceae
Genus Citrus
Order Sapindales
1.5.2 USES OF CITRUS SINENSIS
1. In the
home,oranges are commonly peeled segmented and utilized in fruit cups, salads, gelatins
and numerous other deserts and as garnishes on cake, meats and poultry dishes.
2
They are squeezed daily in the kitchen for
juice.
3
In South America, a dozen whole, peeled
oranges are boiled in 3 pints (1.41 litres) of slightly sweetened water for 20min
and then strained and the liquid is poured over small squares of toast and
slices of lemon and served as soup.
4
Whole oranges are sliced, dried and
pulverized and the powder is added to baked goods as flavoring.
5
Dried orange peels can be used as home made
bath oils.
6
Limonene carbon-base compounds that makes up
around 95% of the oil found in orange peels is often used to give household
cleaners a citrus smell.
7
O range peels can be applied on the skin, in
the night to repel mosquitoes.
8
Orange peels can be used as scent.
1.5.3 FOOD VALUE.
The
Chemistry of the Orange is affected by many factors. On the average,
“Valencia”, Washington Navel”, and other commercial oranges have been found to
poses the value shown in the page.
|
FOOD VALUE PER 100G OF
EDIBLE PORTION
|
|
|
Fruit (fresh)
|
Juice (fresh)
|
Juice (canned unsweetened undiluted)
|
Frozen Concentrate (Unsaturated
undiluted)
|
Juice (dehydrated 380)
|
Orange peel (raw)
|
|
Calories
|
47-51
|
40-48
|
223
|
158
|
380
|
|
|
|
Moisture
|
86.0g
|
87.2-89.6g
|
42.0g
|
58.2g
|
1.0g
|
|
|
|
Protein
|
0.7-1.3g
|
0.5-1.0g
|
4.1g
|
2.3g
|
5.0g
|
1.5g
|
|
|
Fat
|
0.1-0.3g
|
0.1-0.3g
|
1.3g
|
0.2g
|
1.7g
|
0.2g
|
|
|
Carbohydrate
|
12.0-12.7g
|
9.3-11.3g
|
50.7g
|
38.0g
|
88.9g
|
25.0g
|
|
|
Fiber
|
0.5g
|
0.1g
|
0.5g
|
0.2g
|
0.8g
|
|
|
|
Ash
|
0.5-0.7g
|
0.4g
|
1.9g
|
1.3g
|
3.4g
|
0.8mg
|
|
|
Calcium
|
40-43mg
|
10-11mg
|
52mg
|
33mg
|
84mg
|
161mg
|
|
|
Phosphorus
|
17-22mg
|
25-19mg
|
86mg
|
55mg
|
134mg
|
21mg
|
|
|
Iron
|
0.2-0.8mg
|
0.2-0.3mg
|
1.3mg
|
0.4mg
|
1.7mg
|
0.8mg
|
|
|
Sodium
|
1.0mg
|
1.0mg
|
5mg
|
2mg
|
8.0mg
|
3.0mg
|
|
|
Potassium
|
190-200mg
|
190-208mg
|
942mg
|
657mg
|
1,728mg
|
212mg
|
|
|
Vitamin
A
|
200I.U
|
200I.U.
|
960I.u.
|
710I.U
|
1,680
I.U
|
420
I.U
|
|
|
Thiamine
|
0.10mg
|
0.09mg
|
0.39mg
|
0.30mg
|
0.67mg
|
0.12mg
|
|
|
Riboflavin
|
0.04mg
|
0.03mg
|
0.12mg
|
0.05mg
|
0.21mg
|
0.09mg
|
|
|
Niacin
|
0.4mg
|
0.4mg
|
1.7mg
|
1.2mg
|
2.9mg
|
0.9mg
|
|
|
Ascorbic
acid
|
45-61mg
|
37-61mg
|
229mg
|
158mg
|
359mg
|
136mg
|
|
|
|
|
|
|
|
|
|
|