Bioactivity of a Linoleic Acid-Rich Fraction of Ricinus communis L. (Euphorbiaceae) Leaves against the Yellow Sugarcane Aphid, Sipha flava (Hemiptera: Aphididae)

The insecticidal activity of a Ricinus communis leaf hexane extract and its fractions against adult yellow sugarcane aphids (Sipha flava) was evaluated using a contact bioassay after fumigation. The n-hexane extract at 10,000 ppm achieved the highest mortality (80%); the positive control had 100% mortality and the negative control had only 4% mortality over the 72-h experiment time. Chemical fractionation of the hexane extract of R. communis leaves produced multiple fractions, and 10,000 ppm of the F4 fraction resulted in 92% aphid mortality at 72 h. Gas chromatography-mass spectrometry of the F4 fraction revealed linoleic acid as the major compound (84.5%). The R. communis n-hexane extract and linoleic acid could be used for integrated pest control as an ecologically friendly alternative to synthetic chemical insecticides.