INSECTICIDAL ACTIVITY OF CASHEW NUT SHELL LIQUID AGAINST TWO LEPIDOPTERAN PESTS

Cashew nut shell liquid (CNSL) – a byproduct of cashew nut (Anacardium occidentale) by itself is useful for insecticide, fungicide, anti-termite, and medicinal applications. Its insecticidal properties were tested against two caterpillar pests in laboratory during 2007–09. The CNSL – oil and partially hydrogenated preparations were evaluated at 1% concentration for their insecticidal properties against Helicoverpa armigera neonates by ‘artificial diet surface incorporation’ method in ‘no-choice’ assay. Comparisons were made with the ideal botanical neem (active principle azadirachtin, 20% purity). All azadirachtin treated neonates stayed in initial larval instars only leading to ultimate death. CNSL treatments resulted in delayed larval and pupal periods and deformed larvae. Insecticidal activity was recorded by stomach poisoning in ‘diet-incorporation’, but no contact toxicity by ‘direct-spray’ method. The CNSL preparations were also evaluated against Spilarctia bliqua (8 d old, laboratory reared on castor leaves) following ‘direct-spray’ by potter's tower, as well as ‘no-choice leaf dip’ method. Few other botanicals (azadirachtin, karanjin, jatropha aqueous extracts) were also compared. Significant insecticidal activity could not be detected for botanicals in general. Both in ‘direct-spray’ and ‘leaf-dip’ bioassay, CNSL was found ineffective against 8 d old larvae of S. obliqua.