Lab Report: Effect of Cacao Leaves Extract on Mosquito Larvae

Abstract

The objective of this experiment was to investigate the effectiveness of Madre de Cacao (Gliricidia sepium) leaf extract as a larvicide for mosquito larvae (Culex pipiens). Various concentrations of the leaf extract were tested, and the level of effectiveness was determined based on larval mortality. The results showed that higher concentrations of the extract were very effective in killing mosquito larvae, while lower concentrations exhibited moderate effectiveness. This study highlights the potential of Madre de Cacao leaf extract as a natural larvicide, offering an alternative to commercial pesticides and promoting eco-friendly pest control methods.

Introduction

Mosquitoes are vectors of various diseases, including malaria and dengue, which pose significant health risks to humans. To combat these diseases, it is essential to control mosquito populations effectively. Traditional methods often involve the use of chemical pesticides, which can have adverse environmental and health effects. Therefore, there is a growing interest in exploring natural and eco-friendly alternatives for mosquito control.

The Madre de Cacao tree (Gliricidia sepium) is a nitrogen-fixing plant known for its various uses, including as an insect repellent and potential pesticide.

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Previous studies have suggested that Madre de Cacao leaf extract contains compounds that can effectively control pests and insects. This experiment aims to evaluate the larvicidal properties of Madre de Cacao leaf extract against mosquito larvae (Culex pipiens) and assess its potential as a natural and sustainable method of mosquito control.

Review of Related Literature

Foreign Literature:

A foreign study investigated the insecticidal and repellent activities of essential oil derived from Kaempferia galanga L.

rhizomes against booklice (Liposcelis bostrychophila). The essential oil was found to exhibit contact toxicity, fumigant toxicity, and repellency against booklice. Several active constituents of the essential oil were identified, including 1,8-cineole, ethyl cinnamate, ethyl rho-methoxycinnamate, and trans-cinnamaldehyde. These findings suggest the potential of essential oils as natural insecticides and repellents for pest control.

Another foreign study focused on the effectiveness of sweet wormwood (Artemisia annua L.) oil and its individual components as fumigants, contact insecticides, and repellents against red imported fire ant workers (Solenopsis invicta Buren). The study identified active components such as d-camphor, linalool, cineole, α-terpineol, and l(-)-borneol in sweet wormwood oil. These components exhibited insecticidal activity, with cineole and d-camphor showing strong fumigant toxicity. The study highlights the potential of natural oils and compounds as alternatives for pest control.

Local Literature:

A local study explored the larvicidal effectiveness of Madre de Cacao (Gliricidia sepium) leaf extract against household mosquito larvae (Culex pipiens). Different concentrations of the extract were tested, revealing that higher concentrations (50%, 75%, and 100%) were very effective in killing mosquito larvae, while a lower concentration (25%) exhibited moderate effectiveness. This study suggests that Madre de Cacao leaf extract can serve as a natural larvicide and an alternative to commercial mosquito pesticides.

Another local study investigated the antimicrobial properties of Madre de Cacao leaf extract using ethyl alcohol and water as extracting media. The study found that both extraction methods failed to inhibit Escherichia coli (test organism), indicating no significant difference in antimicrobial activity between the two media. However, further research is recommended to explore other potential uses of Madre de Cacao leaf extract as an antimicrobial agent.

Methodology

Madre de cacao is a nitrogen-fixing tree. In some areas, it is referred to as a quick-stick due to its characteristic of growing almost right away just by cutting it and directly planting it in the ground. It is a fast growing tree with a maturity height of 10 meters (33 feet). It is adaptable to almost any soil environment, including infertile soils. It is tolerant to salt spray and water logging. It can tolerate drought for up to 6 to 8 months. This tree can be potentially weedy, but rarely causes a problem. Its ubiquitous characteristic makes it a good alternative for feeds due to its availability in almost all areas in the country.

There are many methods of control that can be implemented to reduce the number of mosquitoes. Local councils may use commercial larvicides (pesticides that kill the larvae) which prevent mosquitoes from maturing to adults. In an effort to help the government combat the disease and eradicate mosquito carrier, the researchers determined the effect of Madre de Cacao (Gliricidia sepium) leaf extract on mosquito larvae. Studies have shown that the plant Madre de Cacao is an insect repellant and has the ability to kill many insects which can become potential carrier of many diseases. At present there is still a wide use of commercial and synthetic chemicals to destroy pests which are potential carriers and are expensive. The researchers are aware of the risk of high toxic chemical compounds and become interested in using natural pesticides derive from plants as a means of destroying pests hence the conduct of this study.

A study done by Alfredo Rabena, a full-time professor at the University of Northern Philippines in Vigan City, found that kakawati leaves are good source of coumarins, a toxic substance that can kill almost all types of pests and insects. Rabena said one kilogram of kakawati leaves, soaked in water overnight, can produce seven gallons of “botanopesticides” (botanical pesticides). “The more leaves the more concentrate the pesticide is,” he said. Rabena said he conducted the study in 1996 in collaboration with a Malaysian chemist, Dr. Nordin Lajiz, at the University of the Philippines in Los Baños, Laguna. “The three-year study found botanopesticides as effective pest control,” he said, adding the technology is being used by rice and vegetable farmers in eight municipalities in Ilocos Sur.

Rabena said he wants to provide Filipino farmers an alternative to commercial pesticide to lessen the cost of production. He said the kakawati plant is endemic to tropical countries such as the Philippines. Meanwhile, Rabena appealed for a P5 million-research grant from the Department of Science and Technology (DOST) to further study the potential of kakawati leaves as an anticoagulant drug. According to research, anticoagulant drugs are given to patients to prevent blood clots from forming after the replacement of a heart valve or to reduce the risk of a stroke or another heart attack after a first heart attack.

Procedure

Plant Material:

Madre de Cacao (Gliricidia sepium) leaves were collected and processed to obtain leaf extract.

Larvicidal Test:

A total of 555 mosquito larvae (Culex pipiens) were used for the larvicidal test. Five different concentrations of Madre de Cacao leaf extract were prepared: 0%, 25%, 50%, 75%, and 100%. The larvae were exposed to these concentrations, and their mortality was recorded over a specified period.

Data Analysis:

The mean mortality rates were calculated to determine the level of effectiveness of Madre de Cacao leaf extract at different concentrations. Analysis of variance (ANOVA) was used to assess significant differences in effectiveness between concentrations.

Results

The results of the larvicidal test showed that Madre de Cacao leaf extract at concentrations of 50%, 75%, and 100% were very effective in killing mosquito larvae (Culex pipiens). The 25% concentration was moderately effective, while the 0% concentration was less effective.

Discussion

The experiment demonstrated the larvicidal properties of Madre de Cacao (Gliricidia sepium) leaf extract against mosquito larvae. The results indicated that higher concentrations of the extract were more effective in killing larvae, with concentrations of 50%, 75%, and 100% being classified as very effective. This suggests that Madre de Cacao leaf extract has the potential to serve as a natural larvicide for mosquito control.

These findings align with previous studies on the insecticidal and repellent properties of natural plant extracts, such as essential oils. Natural alternatives like Madre de Cacao leaf extract offer eco-friendly pest control methods that can reduce the reliance on synthetic chemicals with potential environmental and health risks.

Conclusion

The study concludes that Madre de Cacao (Gliricidia sepium) leaf extract is effective as a larvicide against mosquito larvae (Culex pipiens). Higher concentrations of the extract demonstrated greater effectiveness, indicating its potential as a natural and eco-friendly alternative to commercial mosquito pesticides. Further research and development of Madre de Cacao-based larvicides are recommended to promote sustainable mosquito control methods.

Recommendations

Based on the findings of this study, the following recommendations are provided:

1. Further research should focus on optimizing the concentration and application methods of Madre de Cacao leaf extract for mosquito larvicidal purposes.
2. Educational programs should be conducted to raise awareness among communities about the effectiveness of natural larvicides like Madre de Cacao leaf extract.
3. Collaborative efforts between local farmers and researchers can explore the feasibility of large-scale production of Madre de Cacao-based larvicides for widespread use.
4. Additional studies can investigate the potential of Madre de Cacao leaf extract for controlling other pests and insects, expanding its applications in agriculture and public health.