Dengue Hemorrhagic Fever (DHF) is commonly found in most tropical and subtropical regions. DHF is caused by the dengue virus, which enters the human bloodstream through the bite of the Aedes aegypti mosquito. Aedes aegypti's life cycle starts from the egg, larva, pupa, and adult mosquito stages. The egg, larva, and pupa stages of mosquitoes are in the water, while as adults, mosquitoes actively fly to find food from human blood, animal blood, or plant extracts. Therefore, the most effective effort to break the chain of transmission of DHF is to eradicate the larvae of the Aedes aegypti mosquito. So far, larvae have been exterminated using larvicides such as Dichloro Diphenyl Trichloroethane (DDT), ethyl hexanol, temefos, and various other synthetic compounds in high concentrations that can harm the environment.
A group of students from the Faculty of Mathematics and Natural Sciences studied how galangal rhizome extract could be used as a bio-reductant to eradicate these mosquitoes. They are Yasinta Dwi Salsabila and Mia Luvita Sari (chemistry education), Intan Tri Wahyuni (biology education), Intan Damayanti (physics), and Mifta Fajarwati (chemistry).
"The active compounds found in galangal are saponins, terpenoids, phenolics, flavonoids, carbohydrates, alkaloids, glycosides, phytosterols, and essential oils," said Yasinta Dwi Salsabila. The flavonoid content of galangal has a concentration value that can kill 50% of Aedes aegypti larvae or has an LC value of 50 <50 ppm, which is 29.8 ppm. Mia Luvita Sari added that vegetable larvicides come from natural ingredients toxic to insects but do not harm the environment and human health. Natural larvicides can be found in plants that contain active compounds such as cyanide, saponins, tannins, flavonoids, alkaloids, steroids, and essential oils. "A larvicide can kill immature insects or kill larvae," said Mia. (Dedy, Tj. Lak)