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The alcoholic and hexane extracts of 17 neem ecotypes of India have been found to be toxic to the egg, larval and pupal stages of the cosmopolitan, external gregarious larval parasitoid Bracon brevicornis (Wesm.). In general, the hexane extracts showed higher toxicity against the egg and pupal stages whereas the alcoholic extracts were more toxic against the larvae. Azadirachtin content of the neem ecotypes revealed no apparent correlation with the observed toxicity against different stages of the parasitoid.

A column chromatographic cleanup method to remove aliphatic and aromatic solvent components and different surfactants present in formulated neem was developed. A glass column containing silica gel (60–120 British Standard Sieve) and 250 mL hexane–acetone (6 + 4) was used. Impurities interfering in the region of the azadirachtin-A peak were removed by fractional elution. Recovery of azadirachtin-A was greater than 81%.

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