The effect of feeding of Catharanthus roseus (L.) G. Don leaves to Spodoptera littoralis (Boisduval) larvae on survival, growth, and pupation rate was investigated. Larvae of different weight ranges were raised on fresh C. roseus leaves and on one of their natural host plants, lucerne. Larvae lost weight on C. roseus and did not pupate, whereas 88–100% of the larvae pupated on lucerne. Experiments were done with extracts of fresh leaves or of leaf powder of C. roseus employing the Styropor® method. Feeding inhibition was found to be substantially higher with extracts of fresh leaves than with those of leaf powder. An alkaloid fraction prepared from C. roseus leaves exhibited high inhibitory activity at 0.125%. Among the predominant alkaloid components present in C. roseus leaves, vinblastine was strongly deterrent at 0.04%. When extracts of fresh leaves or of leaf powder of C. roseus were applied at different concentrations to cotton or lucerne, some phagodeterrent effect was observed at relatively high concentrations of the extracts.
The effect of feeding of Catharanthus roseus (L.) G. Don leaves to Spodoptera littoralis (Boisduval) larvae on survival, growth, and pupation rate was investigated. Larvae of different weight ranges were raised on fresh C. roseus leaves and on one of their natural host plants, lucerne. Larvae lost weight on C. roseus and did not pupate, whereas 88–100% of the larvae pupated on lucerne. Experiments were done with extracts of fresh leaves or of leaf powder of C. roseus employing the Styropor® method. Feeding inhibition was found to be substantially higher with extracts of fresh leaves than with those of leaf powder. An alkaloid fraction prepared from C. roseus leaves exhibited high inhibitory activity at 0.125%. Among the predominant alkaloid components present in C. roseus leaves, vinblastine was strongly deterrent at 0.04%. When extracts of fresh leaves or of leaf powder of C. roseus were applied at different concentrations to cotton or lucerne, some phagodeterrent effect was observed at relatively high concentrations of the extracts.