Larvicidal effects of GC-MS fractions from leaf extracts of Cassia uniflora Mill non Spreng.
Invasive weeds are becoming dominant over native plant communities and they are known to contain phytochemicals having biocidal activities. They are researched in order to manage their growth and make use of their phytochemicals. Larvicides of plant origin may serve as an alternative biocontrol technique because mosquito control is becoming a serious issue due to the harmful effects of synthetic insecticides. In the present study the larvicidal activity of Cassia uniflora Mill non Spreng dry leaf powder fractions was studied. Four ethyl acetate fractions, viz. 20%EA, 40%EA, 60%EA, 80%EA, were obtained by column chromatography. The second instar larvae of Aedes aegypti were exposed to fractions with concentrations ranging between 200, 400, 600, 800 and 1000 ppm. Observations for mortality were taken for 8 h of exposure and followed by 24, 48, 72 and 96 h. Among the four fractions, 20% and 60% fractions showed significant larvicidal activity against treated mosquito species at 1000 ppm concentration. From 20% and 60% ethyl acetate fractions, major compounds identified by GC-MS analysis were hexadecanoic acid and ethyl ester which are found to possess antifungal, pesticidal, nematicidal and antioxidant activity while benzyl butyl phthalate is known to inhibit the property of mimicking as ecdysone egonist which could be possible reason for mortality in A. aegypti larvae.