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Organic Insect Repellents for Eggplant

Page history last edited by PBworks 15 years, 4 months ago
An Organic Pesticide for the Eggplant in Antipolo


Description and Rationale


The tropical eggplant is perennial, but is annual in cooler, seasonal climates. There are many different varieties; some have whitish-yellowy firm skin, some are red, others green, and the most familiar to western cultures: purplish-black. They are also different shapes: oblong, oval, and round. The purple fruit seems to be preferred by consumers, but my dad is growing the Thai Yellow Egg variety, which I will be experimenting with. However, these plants has been struggling to survive the ravage of insects, is there an effective way to prevent pests without using possibly harmful chemicals?

What kind of profit might this plant bring the Filipino people? In how many areas can it improve life for them? Most small producers grow their eggplants from transplants because of lack of time, space, and, in temperate climates, the temperature changes. Is this really the safer bet in the tropics, or is seeding essentially more profitable? The raw leaf of an eggplant is toxic; can the people be convinced of its beneficial uses when the leaves are prepared correctly? Can the nutrients in the fruit be used to fight malnutrition inexpensively? Is the scrawniness of my dad’s plants impossible to cure without conceivably dangerous pesticides?

Is there a valid reason for the over use of chemical pesticides on crops here in the Philippines? Or is it simply an unstudied habit? Are there amazing, unfamiliar uses of the eggplant that may help to prevent and/or sooth health complications? Yes there are, but will people be open to the education or will they prefer to continue in there traditional practices? Are there other resources that have gone unused that can be a help with the bug problems?

My plan is to do some deeper research of both eggplants, their place in the tropics, and their nutritional and medicinal values. Then I would like to interview my dad, a gardener and medical doctor, as well as some native non-agriculturalists to better grasp what people’s basic understanding about how to treat bug dilemmas would be, and to clarify what is cultural assumption and what is scientific understanding.

I hope to discover, after further study of my specific variety and an organic solution to its pest problems, the answers to the questions above, and to, hopefully, find a practical (inexpensive) application for the benefit of the needy around us.


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Common Names and Synonyms

Solanum melongena is commonly known as the eggplant. The English name was adopted by 18th century Europeans that marked the resemblance between the whitish-yellow fruit of some eggplants and goose eggs. “Eggplant” is used not only for the fruit but also for the plant in its entirety. This name is used today in the United States, Australia, and Canada, but referred to as Aubergine in Britain, describing the dark purple that is more familiar to the West. There are countless numbers of different names for this plant in different dialects. However the Tagalog name is Talong.




Kingdom: Plantae

  Phylum: Magnoliopsida ( )

  Class:  Asteridae ( )

  Order: Solanales ( )

  Family: Solanaceae ( )

  Genus: Solanum ( )

  Species: S. melongena ( )

Different, and new, varieties of eggplant are being bred/cultivated all of the time. There are many variety names because of the wide selection of fruits that are now being produced, but the variety for my project is the Thai Yellow Egg variety, which is wonderfully self-descriptive, but there is a picture below none the less.


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Morphology and Physical Description

The leaves of the eggplant are lobed and are located alternating on the stem. It grows to approximately 1 meter as a perennial (the eggplant is a perennial, active through the entire year, in the tropics, but an annual, living for only one season or year, in colder climates). The white residue on the leaves which prevent a glossy sheen is common. Its seasonal changes occur with leafing from May to October, flowering from July to September, and the seeds ripen from August to October. The flowers vary from a deep violet to a white color.  The fruits are very similar to the cherry tomato, or baby tomato, with firmer, thicker skin, this similarity is probably because of its part in the Solanaceae family.

 The numerous seeds of the eggplant are round and soft and the internal texture is stringy and moist. The leaves and stem of the plant are poisonous if ingested, which makes it difficult to introduce the benefits of something besides its fruit to people. The new foliage presents itself at the top and bottom of the plant instead of at the ends of the already developed leaf/branches. They don’t grow in the shade and they prefer moist soil.



Getting Food


 Eggplants produce their nutrients through photosynthesis, like all plantae. They grow best with full sunlight and moist, cultivated soil this promotes a nutritional concentration gradient. The Eggplant prefers sandy-loamy soil.

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Eggplants are self-pollinating (which means that they have the male and female organs). The Neem-sprayed eggplants from my experiment have had by far the highest yield and this can be explained because eggplants are pollinated by insects and, I noted, that instead of acting as a pesticide the Neem-spray seemed to attract the insects. Hand-pollination is an option. Some farmers choose to simply transplant the eggplants so that the temperature can be more closely monitored when the seed germinates and begins to establish itself, the young plant should be transplanted in its ninth to tenth week.


Environmental Factors


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 Eggplants are not found in the wild but must be planted or transplanted into cultivated soil. It is hardy in light, medium, or heavy (clay-like) soils and, as previously mentioned, needs sunlight. It is highly sensitive to frost and is healthy until zone 9 which is the temperature zone of 20-30 degrees Fahrenheit, like in Fort Pierce Florida and Houston Texas. The plant requires a pH level of 5.5 to 6.8. 25-30 degrees Celsius is required for a full-potential growing season of flowers and fruits.

 Bees are not particularly attracted to the flowers of an eggplant and it is not generally plagued by insects (too bad for our case, they are).


Origin and Distribution


 The Eggplant originated in India and has been developed in Asia (according to scientists) since prehistory.  It seemed to have become introduced to the West of the world in the 1500s by route of the Mediterranean when the Arabs invaded Persia (its scientific name was derived from Arabic). This is presumed because of the many names that the North Africans had for the plant and the scant terms in Roman and Greek for it.

Importance to People

Though the fruit of the eggplant should not be eaten raw and the leaves should not be ingested the medicinal value of this plant is staggering. The fruit is beneficial to lowering high cholesterol as well as managing high blood pressure. The fruit can also be used as an antidote to poisonous mushrooms. Bruised and with vinegar it can be used for hemorrhoids and abscesses. The leaves can be used as a narcotic (a pain relievant and sedative), or as a kind of salve for burns and sores. The peduncle (or stalk) can be used, as ash, to treat piles (similar to hemorrhoids) or toothaches. There are even more uses I did not find the need to include because I am sure that the basic ideas were understood. Lastly, the familiar use of using the fruit for food as it is highly beneficial to health and can be prepared a number of delicious ways.


Survivability and Endangered Status

 The eggplant is a domestic and fairly popular plant; it is in no danger of escaping the face of the planet with out any hope of return.



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Potential Solutions


Possibility 1



 When my dad informed me of his eggplant problem in response to this biology project we sat on the bed discussing the problem. It wasn’t nematodes, the pest that destroyed the root systems of his tomato plants (as I had investigated in a previous science project); it was probably aphids or possibly multiple different bugs causing mutual damage. In any case, they were attacking the leaves, and the plants looked absolutely pathetic. My dad asked me if I would be interested in including Neem in my experiment and I said absolutely.

Advantages:    Because Neem is, in fact, termite resistant it is speculated to also have a specific chemical that makes it distasteful to all insects, which may mean that this chemical could be released and harnessed in a simple formula by steeping the bruised, blenderized leaves in water, as an easy and inexpensive way to make the bugs cringe and flee from other plants, as well. The Neem tree is very common here in the Philippines (it is part of the mahogany family), it thrives, so it would be a practical resource: available, cheap, and easy to grow. Not to mention it is promotes a healthy environment by discouraging deforestation and encouraging the healthy use of a resource. In the experiment we got our Neem leaves from a neighbor lady named Rowena. I blenderized 1 cup of Neem with 300 milliliters of water, poured it into a recycled olive jar and let it steep over night, then sieved it and sprayed it onto three of our eggplants, we did this every two days for four weeks, and every time we went to spray I recorded the heights of the plants, the number of fruit in each experimental group, and some notes about the general appearance of the plants (i.e. any changes in the plants bug-eateness).

Disadvantages:    However, it has not been proven that the chemical that provides the Neem tree with its protection from termites will protect it from other bugs. One other concern was would it repel the bugs necessary for pollination. Also, even if we discovered a change for the better in the plants that we sprayed with Neem we would not necessarily be able to convince people to accept this new concept and set aside their well developed habits of spraying with store-bought (expensive) pesticides or using none at all. Not to mention that measuring the improvements of the plants during the harshest part of hot season may produce potentially inaccurate results.

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Possibility 2


 Habanera peppers are some the hottest peppers in the world; who knows, maybe insects don’t like spicy food. So I ground two fresh habaneras and added it to 300 milliliters of water, gave it a good shake in another recycled jar and sprayed it on three more of my dad’s eggplants, which we also did every two days for two weeks, measuring as we went.

Advantages:    Hot chili peppers are fairly easy to acquire and grow here in the Philippines. Hot peppers are the main ingredient in a Philippine sauce called Sukang Anghang which means “spicy vinegar”, which is very popular here. 

Disadvantages:    Habaneras are more difficult to acquire than other kinds of hot peppers here in the Philippines. Also, habaneras do not offer much in the way of nutritional value to be used as something more than an eggplant pesticide for the poor families that would be growing it. The oils in the habanera make the spray risky business, since the slightest amount could make someone very uncomfortable if it made its way into their eyes.

After completing the experiment I made a graph of the compiled lengths of the eggplants.


 We conducted this experiment over the course of four weeks and while we recorded no significant statistical growth or profound improvement in the general appearance of the plants (as far as their bug-eateness) the yield of both of the Neem and Habanera groups was better. There were three plants in each experimental group and both the Neem group and the Habanera group produced two fruits total over the course of the four weeks, however, in the control group there were no fruits at all. This may be due to the fact that eggplants are pollinated by insects and therefore while the mixtures may have disappointed us as pesticides they may have actually attracted insects and increased pollination. In the following graph some of the bars do not have as many marks above them as others, because in my compilation of the measurements I only made a mark when the plant had grown, and not all of the plants measured differently every two days when I would measure again.


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Morris, Rich. “Solanum melongena.” Plant For A Future. ©1997-2000. 14 April 2007. http://www.ibilio.org/pfaf/cgi-bin/arr_html?Solanum+melonga


Eggplant. 14 April 2007. Wikipedia the Free Encyclopedia. 14 April 2007. http://en.wikipedia.org/wiki/Eggplant


Annual. ©2007. The Free Dictionary. 14 April 2007. http://www.thefreedictionary.com/annual


“Eggplant”. USDA.gov. 2007. Plant Guide. 16 April 2007. http://plants.usda.gov/plantguide/doc/pg_some.doc


Dreyer, M. “Neem”. ©1998. http://echotech.org/network/modules.php?name=News&file=article&sid=578


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