Laboratory and field evaluation of neem (Azadirachta indica Juss.), pongamia (Pongamia pinnata L.), chinaberry (Melia azedarach L.) extracts and commercial neem formulations against tobacco caterpillar, Spodoptera litura F.

Three neem formulations -NeemAzal F I containing 10,000 ppm azadirachtin (aza) at 50 and 30 ppm, NeemAzal F II containing 50,000 ppm aza at 50 and 25 ppm, Fortune Aza containing 11,000 ppm and 1500 ppm aza at 50, 30 and 15 ppm concentrations and neem (Azadirachta indica A. Juss.) extracts (CTRI-I, II, and DOR-I) containing 15,000 ppm aza, CTRI-III containing 80,000 ppm aza, CTRI-IV containing 30,000 ppm aza, all at 50 ppm concentration, 1.5% oil and seed extract of chinaberry (Melia azedarach L.) (DOR-II) at 0.005% a.i. and four pongamia (Pongamia pinnata L.) seed extracts (1.0% cone.) including pongamia oil 1.5% cone. were evaluated in comparison with 2% aqueous neem seed kernel suspension and chlorpyrifos (0.05%)in the laboratory and nursery against tobacco caterpillar, Spodoptera litura during the 1994 and 1995 seasons. Results indicated that NeemAzal F I and II at 50 ppm concentration, NSKS 2% and chlorpyrifos 0.05% gave significant protection to tobacco seedlings from the Spodoptera damage followed by NeemAzal F II (25 ppm) and NeemAzal F I (30 ppm). Fortune Aza at 50 ppm gave equal protection as chlorpyrifos 0.05% and NSKS 2% up to nine days after spraying and while not differing from its medium concentration of 30 ppm, it is superior to its lower concentration of 15 ppm. These results confirm the earlier findings that neem formulations at 30 ppm aza concentration could effectively protect the tobacco seedlings from the Spodoptera damage up to nine days after spray. All the neem extracts were significantly more effective against S. litura an tobacco than pongamia treatments. Neem oil at 1.5% cone, was found highly effective and on par with 2% NSKS, chlorpyrifos and CTRI-III neem extract. Pongamia CTRI-III (pongamia oil 1.5%) and alcoholic extract of neem without oil (CTRI-IV) at 50 ppm were the next best treatments. Further it is evident that alcoholic extract with neem oil gave better protection than without oil. The neem extracts from seeds of A. indica gave better, protection than those from seeds of Melia azedarach which does not contain any azadirachtin contrary to the earlier findings.