The Potential Use of Coffea arabica Grounds as Aedes Aegypti Mosquito Larvicide

Abstract

The Department of Health declared a national dengue epidemic in August 2019 due to a 98% increase in the cases of dengue from January to July 2019. The government pushed for mosquito control; while the WHO suggested the use of larvicides since it attacks mosquitos before they can even take flight. Because of these recommendations, the researchers investigated the potential use of coffee grounds as mosquito larvicide.

Used coffee grounds were utilized as it is free and around 6 million tons of it are thrown annually. Moreover, various researches reveal its main components to be phytochemicals or alkaloids (trigonelline and caffeine), terpenoids (diterpene), and phenolic (chlorogenic acid), which are proven to be larvicidal. To test its use as a larvicide, used coffee grounds were dried and steeped in organic ethanol which was stirred occasionally every 30 minutes for 8 hours. The mixture was filtered to separate the liquid that contains phytochemicals. To remove the alcohol, the liquid was boiled in a pot where the leftover was used in the experiment. Five larvae were put in containers of different extract concentrations where they were monitored 24/7. The initial concentrations used were 2mL/100mL, 3mL/100mL, and 4ml/100 mL, respectively. Two trials were done to ensure the integrity of results. It took 23 hours for trial 1 to take effect on the mosquito larvae in3mL/100mL and 4ml/100 mL solutions, killing one larvae in each container. There was no larvicidal effect with the 2mL/100mLsolution. After 35 hours, 3mL/100mL concentration contained five (5)dead larvae while 4mL/100mL concentration contained four (4) dead larvae. In the 2mL/100mL concentration, no effect on mosquito larvae was observed. In trial 2, there was no progress inthe2mL/100mLsolutioneven after 23 hours. The 3mL/100mL solution resulted in one (1) dead larva. In the 27th hour,the3mL/100mL and 4ml/100mL solutions both contained three(3)dead larvae. On the 28th hour, the 4mL/100mL solution contained four (4) dead larvae.

Findings show that longer exposure time in the extract at increasing concentration increase the larvicidal efficacy of used coffee grounds extract. Other researches of Satho, et. al. (2015), Dieng, et. al. (2018) and Aditama, et. al. (2018) revealed used coffee grounds have larvicidal properties regardless of the concentration. The brown color of the solution is useful in serving as ovitrap but is not suggested for use in waterways as it may be a pollutano. The extraction of pure phytochemicals without melanoidin, which is responsible for the browning of coffee, is highly suggested.