Using Smoke Condensed Liquids from Pruned Fruit-Tree Branches for Aedes Mosquito Larva Control

Abstract

Some mosquitos are disease-causing vectors. Their widespread existence poses a great threat to disease control worldwide. Finding an effective, low-cost solution for mosquito population control is desperately needed. Pruned branches from three fruit trees of date, pomelo, and guava were chopped, dried, and smoldered to form biochar and smoke. The smoke was condensed at 6 °C to form a smoke condensed liquid (SCL) to be used as a larvicide for mosquito larva control. The SCL had a smoky smell, minimal nutrients, and little metal contents, yet contained plenty of phenolic molecules commonly used as biocides. Via bacterial inhibition zone tests, ten percent of the date, pomelo, and guava SCLs had 1.44, 1.13, and 0.83 times higher bactericidal effects, respectively, than the use of 75% ethanol. The effectiveness of bacterial inhibition was positively related to the amounts of volatile compounds in the SCL liquids. As for larvicidal effects, a ten percent solution of the date and pomelo SCLs killed all tested larvae within 2 hrs. The reactive time versus each SCL’s LC50 was determined and fitted with a first-order mathematic model. The adopted model and its estimated parameters showed satisfactory results in presenting the dose–effect relationships in larval mortality of all the tested SCLs. Finally, the liquid pHs and dissolved oxygen (DO) over time were examined for their effectiveness and variation, respectively, and the SCL addition was concluded as the sole key factor in the mortality of the tested larvae.