RESUMO
The repulsive activity of Cestrum parquii on the feeding behaviour of Pieris brassicae L. and Spodoptera littoralis Boisduval was studied. Antifeedant effect was observed at regular intervals during a week. Meal uptake was stopped after the first day, showing a strongly antifeedant effect of C. parquii extract on these two species. The impact of C. parquii with different concentrations of dry extract (2, 4, 8, 16, 32%) delayed the larval growth of Spodoptera littoralis Boisduval compared to untreated insects. Abnormal metamorphosis was observed with concentrations of 8 and 16% leading to death and abnormal morphogenesis. The antifeedant activity of C. parquii was also observed in S. littoralis and measured by the evolution of food uptake and the weight of larva. Effect seemed to be proportional to extract concentration in the diet. High concentration (32%) stopped growth in the earlier instar.