Agriculture & Food, Volume 9, 2021

Abstract: The eucalypt weevil, Gonipterus platensis Martelli (Coleoptera: Curculionidae), is a main defoliator beetle of these trees worldwide. In Chile, it occurs widely in eucalypt plantations, and there are areas where parasitoids have not adapted. The antifeeding and insecticide effect of Cestrum parqui L'Hérit (Solanaceae) aqueous leaf extracts on third instar larvae was evaluated at various concentrations (0.0, 0.6, 1.2, 2.4, and 4.8% w/v), that were applied in laboratory bioassays to fresh eucalypt leaves, with five replicates. The antifeeding effect was estimated by the foliar area consumed at 24 h. Mortality was determined daily for 11 d. For each concentration, mortality relative to the control and LC50 were determined. This extract had a high antifeeding effect at all concentrations, reaching 100% at 2.4 and 4.8% w/v. Mortality was directly related to concentration. The extract was effective as bioinsecticide, reaching 92% mortality at 4.8% w/v on day 11. The lowest LC50 was 0.87% w/v on day 7. These results indicate that this extract would constitute an efficient alternative in integrated management programs of the pest in eucalypt plantations.