EFFECT OF BISABOLANGELONE ON DEVELOPMENT OF CYDIA-POMONELLA LARVAE AND OVIPOSITION OF THE FEMALES

The effects of bisabolangelone on the development of codling moth larv ae, Cydia pomonella L., and on ovipositional behaviour of the females were studied under laboratory conditions. Entry of the neonate larvae into apples and their development on a semi-synthetic medium were comp letely inhibited when the larvae were exposed respectively to 10 mu g a.i./cm(2) and 20 mu g a.i./ml of this compound. While concentrations of 1.25 to 5.0 mu g a.i./ml bisabolangelone in the medium did not sign ificantly affect larval development, exposure of the larvae to a highe r rate (10 mu g a.i./ml) resulted in 80% mortality during the first we ek. Nevertheless, the larvae which survived the treatments underwent f urther development until emergence of the adults. No significant chang es in duration of larval or pupal periods were recorded. Oviposition o f the females in plastic beakers, whose inner surfaces were partially painted with two concentrations of bisabolangelone (1.25 to 5.0 mu g a .i./cm(2)), was significantly reduced and the eggs were mainly laid on the parts painted with the ethanol solvent alone. When the inner surf ace of the cups was completely treated (i.e. top, bottom, and side) wi th similar concentrations of bisabolangelone, a dramatic reduction in oviposition occurred and the eggs were mostly laid on the bottom of th e beakers. While this compound did not significantly influence egg hat ch, it inhibited the normal upward movement of the adults in the cups and migration of the newly hatched larvae through perforations of the lids.