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Effect of Inexpensive Plants Extracts to Use As A Natural Insecticide To Manage Different Insects

Table of Contents


  • Objectives


  • Introduction
  • Biopesticidal potential of some local plants
  • Eucalyptus
  • Calotropis
  • Aedes mosquito


  • Research Methodology
  • Procedure of extraction
  • Preparation of stock solution
  • Bioassay
  • Exposure
  • Results


  • Summary of research work


  • References /Outcomes

Chapter#1: Objectives


  • To test the effects of  inexpensive plants extracts to use as a natural insecticide to manage different insects like house fly and mosquito etc.
  • To evaluate the bio-pesticidal potential of some local plant extracts against selected insects.
  • To improve my analytical skills.

Chapter#2: Introduction


Biopesticidal potential of some local plants

Over year, chemical pesticides had made a great contribution to the fight against pest and diseases. However their widespread and long term use resulted in insecticide resistance and bio-magnification of insecticides, which in turn resulted in many primary and derived agricultural products arose, which endangered both the general environment and human health (Shen and Zhang, 2000). The use of synthetic organic insecticides in crop pest control programs around the world has caused tremendous damage to the environment, pest resurgence, pest resistance to insecticides and lethal effect on non-target organisms (Abudulai et al., 2001).

Biopesticides are certain type of pesticides derived from natural materials like plants (US Environment Protection Agency pesticides, 2008).

Biopesticides are attracting global attention as new tool to kill or suppress pest population such as weeds, plant pathogen and insects while posing less risk to people and environment than synthetic pesticides (Saxena and Panday, 2001).

Globally, the use of biopesticides havesteadly increased by about 10 percent (Bailey and Mupondwa, 2006). Biopesticides are typically derived from living organisms like plants (Kabaluk and Gazdik, 2005).

In recent years use of many of the former synthetic insecticides in mosquito control programe has been limited. It is due to lack of novel insecticides, high cost of insecticides, harmful effects on human health (Russell et al., 2009). Mosquito can transmit more diseases than any other group of arthropods and effect millions of people throughout the world. WHO has declared the mosquito as public enemy number one (Lopez and Pascual, 2010).

In the past decades, apart from the pyrethrum which has attained international and commercial acclaim due to its high effectiveness and broad spectrum insecticidal activity, very few natural insecticides have been developed (Rajapake and Ratnaseka, 2008).

In contrast with older chemicalsor synthetic pest control strategies which generally utilized a single chemical, and hence a single mode of action, modern biopesticides seek to take a more holistic approach. This holistic approach recognize that chemical mode of action are necessary or beneficial, but not always sufficient on their own, for successful pest control (Bailey et al., 2011)

The resistance to biopesticides in target organism was not easily generated unlike in many cases of their chemical counterparts. They are fast becoming a new trend in the global pesticide industry.

Plants that I was used as a biopesticides Eucalyptus and Calotropis . Some eucalyptus species have attracted attention from horticulture global development researchers and environmentalist because of desirable traits such as:

  • Fast growing sources of wood
  • Producing oil
  • Use as a natural insecticides
  • Used to drain swamp
  • Use for fragrance
  • Act as insect repellent
  • Antimicrobial property

Outside their natural ranges eucalyptus are both lauded for their beneficial economic impact on poor population.

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Eucalyptus was introduced in Australia to the rest of the world following the Cook expedition in 1770. Collected by Sir joseph Bank botanist on expedition it was subsequently introduced to many parts of the world.

Eucalyptus are the basis for several industries such as saw-milling pulp, charcoal and others.

Eucalyptus oil is readily steam distilled from the leaves and can be used as industrial solvent. It is also used an antiseptic.

It has insect repellent properties  and is an active ingredient in some commercial mosquitoes repellent.

Eucalyptus is the principal source of eucalyptus oil worldwide.

Calotropis is a genus of flowering plants in the dogbane family, Apocynaceae, first described as a genus in its native to southern Asia and North Africa.

They are commonly known as milkweed because of the latex they produce. Calotropis species are considered common weeds in some parts of the word. The flowers are fragrant and are often use in making floral tassels in some mainland southeast Asian cultures. Fibers of these plants are called madar or mader. Calotropis are usually found in abandoned farmland.

The milky exudation from the plant is a corrosive poison. Calotropis species are poisonous, calotropin, a compound in the latex, is more toxic than strychinine.

Calotropin is similar in structure to two cardiac glycosides which are responsible for the cytotoxicity of Apocynumcannabinum.

Extracts from the flowers of calotropis have shown strong cytotoxic activity. The extracts also harmful against mosquito, and also for human beings that harm the human eyes.

Cattle often stay away from the plants because of their unpleseant taste and their content of cardiac glycoside.

 Effect Of Inexpensive Plants Extracts to Use As A Natural Insecticide To Manage Different Insects

Eucalyptus Plant leaves (Fig: 1)

 Effect Of Inexpensive Plants Extracts to Use As A Natural Insecticide To Manage Different Insects

Calotropisgigantea (Fig: 2)

Aedes Mosquitoes

  • Distribution

Worldwide, the geographical range of Aedes mosquitoes extends well into Northern and arctic areas, where they can be vicious biters and serious pests to both people and livestock.

  • Eggs

Eggs are usually black, more or less ovoid in shape, and are always laid singly. Careful examination shows that the eggshell has a distinctive mosaic pattern. Eggs are laid on damp substrates just beyond the water line, such as on damp mud and leaf litter of pools, on the damp surfaces of clay pots, rock-pools and tree-holes. Eggs can withstand desiccation, the intensity and duration of which varies,but in many species they can remain dry but viable for many months or occasionally a year or more. When flooded, some eggs may hatch within a few minutes, while others of the same batch may require longer immersion in water before they hatch, and consequently hatching may be spread over several days or weeks. Even when eggs are soaked for long periods some may fail to hatch because they require several soakings followed by short periods of desiccation before hatching can be induced. Even if environmental conditions are favourable, eggs may be in a state of diapause and will not hatch until this resting period is terminated. Various stimuli, including reduction in the oxygen content of water, changesin day length, and temperature, may be required to break diapause in Aedes eggs. Larvae of many Aedes species occur in small container-habitats (tree-holes, plant axils, etc.) which are susceptible to drying out; thus the ability of eggs to withstand desiccation is clearly advantageous. Desiccation and the ability of eggs to hatch in instalments can create problems with controlling the immature stages .

  • Larvae

Aedes species usually have a short barrel-shaped siphon, and there is only one pair of subventral tufts, which arises about one-quarter or more from the base of thesiphon. There are atleast three pairs o fse tae in the ventral brush.The antennae are not greatly flattened and there are novery large setae on the thorax. These characters should separate Aedes larvae from most of the culicine genera, but not unfortunately from larvae of South American Haemagogus.

  • Adults

Many, but not all, Aedes adults have conspicuous patterns on the thorax formed by black, white or silvery scales (Fig. 3.3, Plate 3), and in some species yellow and/or brownish scales are present. The legs often have dark and white rings (Fig. 3.4b). Aedesaegypti, often called the yellow fever mosquito, is readily recognized by thelyre-shaped silvermarkings on the lateral edges of the scutum. Scales on the wing veins of Terminal abdominal segments of an Aedes larva, s.

 Effect Of Inexpensive Plants Extracts to Use As A Natural Insecticide To Manage Different Insects

Aedes mosquito (Fig: 3)

 Effect Of Inexpensive Plants Extracts to Use As A Natural Insecticide To Manage Different Insects

Aedes larva (Fig: 4)

Chapter#3 Research Methodology

Research Methodology:

  1. Selection of plants
  2. Procedure of Extraction
  3. Preparation of stock solution
  4. Susceptibility test (Bioassay)

1). Selection of plants:

Extraction was the crucial first step in preparation of plant formulation, because it was necessary to extract the desired chemical component from the plant material for further separation and characterization.

Plants that was used for experiment such as:

Eucalyptus globules


2). Procedure of Extraction:

  1. Fresh leaves of plants were taken and they were rinsed with water. All the dust and debris should be removed from the leaves.
  2. After rinsed leaves are placed in the incubator at 30 degree centigrade for 2 days for drying purpose.
  3. When the leaves were dried, remove from the incubator and grind finally in powdered form with the help of grinder machine.
  4. Methanol is used for the better extraction. 100ml of methanol is used for the preparation of extracts.
  5. Conical flask are used for this purpose. Prepare solution of methanol and leaves powder in conical flask and covered with aluminum foil.
  6. Then the flask were agitated at 100 oscillation to 1 min for one day. ( For better shaking, use Refrigerator shaking incubator for whole night at the temperature of  30 degree centigrade) these oscillation produce suspension which was filtered with the help of filter paper.
  7. Separate the residue and keep the solution on magnetic stirrer for 30 degree centigrade for one day for, for the purpose of evaporation of methanol.
  8. Methanol completely evaporate then the left behind is called extract. After obtaining the extract, distilled water was used to form different concentrations.

 Effect Of Inexpensive Plants Extracts to Use As A Natural Insecticide To Manage Different Insects

Dried leave of plants Fig. 5

 Effect Of Inexpensive Plants Extracts to Use As A Natural Insecticide To Manage Different Insects

Fine powder of leaves Fig.6

 Effect Of Inexpensive Plants Extracts to Use As A Natural Insecticide To Manage Different Insects

Suspensions of leaves powder with methanol Fig.7

 Effect Of Inexpensive Plants Extracts to Use As A Natural Insecticide To Manage Different Insects

Refrigerator shaking incubator Fig.8

3. Stock Solution:

Stock solution is a concentrated solution that will be diluted to some lower concentration for actual use. Stock solution are used to:

  • Preparation time
  • Conserve materials
  • Reduce storage space
  • Improve the accuracy with working lower concentration solution are prepared.
Preparation of Stock solution:

I prepared 10% stock solution, took 2.5g of extract of Calotropis mix it with 25ml water, as a result the solution was ready, that is called stock solution. Then prepared three dilutions of this solution.

For Calotropis:

                Dilutions              Stock Solution Distilled Water
                   5%                     1ml        19ml distilled water
                  15%                     3ml        17ml distilled water
                  25%                     5ml        15ml distilled water

For Eucalyptus:

               Dilutions Stock solution Distilled Water
10% 3ml 15ml
25% 5ml 18ml
50% 8ml 20ml

4. Susceptibility test:


The determination of relative strength of a substance (e-g toxicant) by comparing its effect on a test organism with that of a standard preparation is called bioassay.

Material Required for Bioassay:

  • 2-3 White Papers
  • 10 Dispose able Plastic cup
  • Permanent black marker
  • Larvae of Aedesaegypti
Procedure of Bioassay:
  1. I took dispose able plastic cups washed under tap water and dried properly.
  2. Then I took two white papers and cut them into pieces according to the bottom of plastic cups.
  3. Then stock solution which was prepared already,made its three dilutions of each extracts.
  4. 10-12 larvae was dipped  in these solution in the cup for different time hours and checked the mortality of larvae after different intervals of time.


Mortality in different groups of dilutions:


   Groups    2 hours 4 hours    6 hours 8 hours 10 hours 12 hours
5%(1) 1larva 3 larvae
5%(2) 3 larvae
15%(1) 9 larvae 12 larvae
15%(2) 11 larvae 12 larvae
25%(1) 11 larvae
25%(2) 12 larvae 12 larvae
Results of exposure:

1.In each dilution there was maximum mortality after 4 hours of the exposure.

So, I found that calotropisgigantea was very effective botanical against the larvae of Aedesaegypti.


Mortality in different groups of dilutions:

Eucalyptus globulus:

    Groups     2 hours 4 hours 6 hours 8 hours 22 hours
10%(1) 2 larvae
10%(2) 5 larvae
25%(1) 1 larva 11 larvae
50%(1) 2 larvae 11 larvae
50%(2) 1 larva 3 larvae 10 larvae
Results of exposure:
  1. According to the above results there was no mortality after 2 hours.
  2. After 4 hours only 1 larva found dead in the dilution no 2 of 50%.
  3. After 6 hours of exposure, rate of mortality increased gradually.
  4. Rate of mortality increased rapidly after 6 hours and till 22 hours (whole night) maximum mortality occurred.

So, it was found that Eucalyptus globules had good biopesticidal action against A. aegypti larvae.

Chapter#4: Summary of the Work

Summary of the work:

Synthetic insecticides are harmful for environment , human beings and animals, which become the cause of different kind of problems. Commonly these synthetic insecticides affect the chemistry of atmosphere.

By keeping in view all these reasons I used some local plants in which biopesticidal potential was present, and it was friendly with the environment.

I used Eucalyptus globulus and Calotropisgigantea that had biopesticidal properties.

I washed these plants and then grand it into fine powder to get the extracts of these plants, then made stock solution, and then further made dilutions from them. I choose the larvae of A.aegypti  as a model animal to check the effects of these extracts on them. I gave the exposure to larvae of both extracts dilutions, as a result of exposure mortality was occurred. So in result of that I came to conclusion that, local plants have biopesticidal quality


The need to use biopesticides arises from the facts that the synthetic pesticides are harmful to humans, and the entire ecosystem due to high toxicity and persistence. Also, they are too expensive for the poor farmers in the developing countries of the world. On the other hand, biopesticidesare cheap and bio-degradable and are therefore environmentally friendly.

Thus I came to conclusion that,some local plants have biopesticidal properties.

Chapter#5: Outcomes/References

  • Shen, Y. C. and Zhang Y. B.(2000).Biopesticides chemicals industry press, Beijing.
  • Abudulai M et al.,(2001). Parasitism and predation on eggs of Leproglossusphyllopus(L) (Hemiptera, Coreidae) in cowpea: Impact of endosulfan sprays. J.Agric.Urban Entomol.,18; 105-115.
  • Saxena S, Pandey A.K.(2001). Microbial metabolites as eco-friendly agrochemicals for the next millennium. Appl Microbial Biotechnol.,55; 284-288.
  • Bailey, K. L. Mupondwa E. K.(2006). Developing microbial weed control products: commercialization, biological and technological consideration, Binghamton N. Y. USA, 431-473.
  • Kabaluk T, Gazdik K: (2005). Directory of  microbial pesticides for Agricultural crops in OECD countries. Agriculture and Agri-Food.
  • Russell T. L., Kay B. H., Skilleter G. A. (2009). Environmental effects of mosquito insecticides on sartmarshinvertebratesfauna.Aqua Biol., 6; 77-90.
  • Lopez, M. D. and Pascual, M. J.(2010). Industrial crop and products., 31; 284-288.
  • Rajapake, R. H. S. and D Ratnaseka.(2008). Pesticidal potential of some selected tropical plant extracts against Callosobruchusmaculates F. and Callosobruchuschinensis L, Tropical AgriculturalResearchand Extension, 11; 69-71.
  • Bailey K. L. et al.,(2011). Determining the infection processo of Phomamacroscoma that leads to bioherbicidal activity on broad leaved weeds.Biol Control., 59; 268-276.

I learnt many things that I had just theoretically studied in literature. The thing I observed during my internship period is that there is a big differences in practical and theoretical life and this may be due to some different factors and external environment. Internship also improve my analytical skills. During my study I just theoretically studied about different instruments and their operations but after my internship now I have full command on these equipments. I can operate them easily without any hesitation. During my internship period I also learnt team work that how team efforts made all the work easy and successful. Now I also have full command in performing different lab activities and in solution preparations.

Now all these things were a part of my cognitive learning.


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