Bernard Dominic C. Magan, Thea Angela P. Silayro, Ma. Phobe T. Subo (March 2012)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
In order to address the need of the science community to kill Aedes aegypti, the primary vector of dengue hemorrhagic fever, the researchers studied the larvicidal and ovicidal properties of the crude and aqueous extracts of Psidium guajava leaves. Crude extracts of different concentrations (50.0, 75.9, 100.0, 1000.0 and 2000.0 ppm) and of aqueous extracts were tested against Aedes aegypti eggs and larvae. Twenty-five larvae and twenty-five eggs were submerged in 150 mL of each concentration, the three replicates each for 72 hours. Unhatched eggs and dead larvae were counted manually, and hatch rates and larval mortality were solved. Lethal concentrations 50 and 99 were obtained using the probit analysis of SPSS. No eggs hatched in the ovicidal tests since the methods used were anomalous, and therefore, no conclusions can be formed. In the larvicidal tests, the results, in both trials, show and increasing trend in terms of percent mortality. The LC50 and LC99 values for the first trial were 100.32 and 110053.41 ppm, respectively. The LC50 and LC99 values for the second trial were 89.57 and 98253.39 ppm, respectively. The aqueous extracts, on the other hand, present 100% larval mortality for both trials. These results suggest that the crude and aqueous extracts from Psidium guajava leaves can be an effective larvicidal against Aedes aegypti.