Indian Journal of Entomology

Laboratory experiments were conducted to study the effect of oils of patchouli (Pogostemon patchouli Pellet) and neem (Azadirachta indica A. juss) on mortality, developmental duration, relative toxicity and LC₅₀ against cabbage aphid, Brevicoryne brassicae L. After 24 hours of treatment, the mortality of nymphs were significantly higher at 0.5 to 2.5% patchouli and 2.0 to 2.5% concentration of neem oil in comparison to control. After 48 hours of treatment, the nymphal mortality of 100% was obtained even at low concentration of 0.5% patchouli oil. After 72 hours of treatment, the nymphal mortality increased to 91.25% even at 0.4% patchouli oil in comparison to water (32% mortality). There was prolonged nymphal duration at higher concentration of neem oil i.e. 1.0, 1.5, 2.0, and 2.5%. The LC₅₀ value determined for patchouli oil was 0.28% and 1.57% for neem oil. The relative toxicity test after 24 hours of treatment indicated that patchouli oil was 5.54 times more toxic than neem oil.