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Azadirachtin‐A and tetrahydroazadirachtin‐A concentrates: preparation, LC‐MS characterization and insect antifeedant/IGR activity against Helicoverpa armigera (Hübner)
Author(s) -
Sharma Vandana,
Walia Suresh,
Dhingra Swaran,
Kumar Jitendra,
Parmar Balraj S
Publication year - 2006
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.1265
Subject(s) - helicoverpa armigera , azadirachtin , insect , biological pest control , biology , biopesticide , noctuidae , helicoverpa , toxicology , pesticide , pest analysis , botany , larva , ecology
A 60% azadirachtin‐A concentrate has been obtained through repeated precipitation with hexane from a methanolic solution of a 20% concentrate. Azadirachtin‐A (90%) has been obtained by medium‐pressure liquid chromatography of the 60% concentrate with an RP‐18 column and a methanol + water (1 + 1 by volume) solvent system. Catalytic hydrogenation of the 60 and 90% azadirachtin concentrates yielded the corresponding tetrahydroazadirachtin concentrates. Dihydroazadirachtin and tetrahydroazadirachtin formed during the first 5 h of hydrogenation were identified by LC‐ESI‐MS on the basis of their unique mass fragmentation pattern. The efficacy of tetrahydroazadirachtin concentrates in inhibiting the feeding and growth of Helicoverpa armigera (Hübner) larvae has been compared with that of azadirachtin concentrates. They were in general more active and deterred larvae from feeding at all concentrations. Tetrahydroazadirachtin‐A (90%) and azadirachtin‐A (90%) with respective IC 50 values of 280 and 390 mg L −1 were effective as insect growth regulators, while tetrahydroazadirachtin‐A (90%) displayed higher antifeedant activity (AI 50 14 mg L −1 ) against the test insect. Copyright © 2006 Society of Chemical Industry