Chemical studies of some plant with antifeedant activity against the larvae of anomalous emperor moth nudaurelia belina (W) saturnidae

The larvae of Nudaurelia belina (W)(Saturnidae) which is commonly known as Anomalous Emperor Moth defoliate Anacardium occidentate (cashew nut) and mangifera indica (mango), all belonging to the family Anacardiaceae. Two out of twenty six Tanzanian plant species known to have medicinal/or repelling properties screened for antifeedant activity against the pest (N. belina) were chemically investigated so as to isolate the active principles. The choice was based mainly on their high antifeedant activity and easy availability. Three of the 5,7-deoxygenated coumarins isolated from the petroleum ether extract of the root bark of Toddalia asiatica (L)(Rutaceae) exhibited high potency against N, belina. Toddanol 46a), dihydrotoddanol (46b) and toddalactone (46d) with hydroxyl group s) showed activity against the pest at a concentration of 0.05 as opposed to toddaculin (85) and toddanone (46c) which were inactive even at 0.5%. The observed activity is probably due to the -0H groups(s). The alkaloid, dihydrochelerythrine (84a) which was also isolated from the petroleum either extracts of the root bark of T. asiatica showed high activity against the pest at the same concentration. The petroleum ether extract of the root bark of Celtic durandii (Ulmaceae) gave yellowish oil, C2F3 (not fully characterized yet). This compound showed activity against the same pest at a concentration of 0.05%.