Biological activity of some plant extracts against Pieris brassicae (Linn.)

In the present study, aqueous extract of eight plants, namely Azadirachta indica A. Juss, Melia azedarach Linn., Lantana camara L. Moldenke., Cannabis sativa Linn., Nerium indicum Mill., Eucalyptus sp., Ricinus communis Linn. and Solanum nigrum Linn. were tested for antifeedant and toxic effects against Pieris brassicae (Linn.). The ethanol extract of four potential plants were further tested for their biological activity against the test insects. Aqueous extract of A. indica and M. azedarach repelled maximum number of larvae protected 94.0 per cent and 89.2 per cent cabbage foliage, respectively. Aqueous extract of M. azedarach, N. indicum and A. indica showed higher mortality of larvae (19.6, 19.6 and 18.5%, respectively) while R. communis was the least toxic resulting in 8.9 per cent larval mortality. In case of ethanol extract, seed extract of M. azedarach protected 58.3 per cent cabbage foliage while Eucalyptus sp. protected minimum cabbage foliage. The maximum protection to the cabbage foliage was provided at 5 per cent of M. azedarach (88.3%) and A. indica (82.5%). Ethanol extract of A. indica exhibited statistically higher larval mortality of 50.0 per cent and N. indicum the lowest mortality of 3.2 per cent. In general, antifeedant and larval mortality was dose dependent.