Seed coat phenolic compounds of Cajanus cajan as chemical barrier in formulation of artificial diet of Spodoptera litura (f.)

Spodoptera litura failed to develop on artificial diet prepared with whole red gram (Cajanus cajan) flour or diets prepared after soaking or after boiling. Removal of seed coat considerably improved the quality of the diet. Therefore, phenolic compounds were extracted from the seed coat of red gram and added in different proportions in the dehusked red gram based diet. Similarly studies were also carried out with residue obtained after extraction and with original seed coat. It was observed the toxicity of phenolic extract could be tolerated by the larvae when they are present in low level in the diet. However, use of higher levels of phenolic extracts resulted in higher larval mortality. It was also observed that larvae of S. litura could not tolerate phenolic compounds at early stages while at later stages they might have tolerated the toxic effect or metabolized it to some other non-toxic compound. It was also proved that residue obtained after extraction of phenolic compounds also contained some substances responsible for the suppression of larval development. The study showed the presence of 18 different peaks but only four peaks were identified as chlorogenic acid, gallic acid, hydroquinones and syringic acid.