Field efficacy of imidacloprid and Steinernema carpocapsae in a chitosan formulation against the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae) in Phoenix canariensis.

BACKGROUND The invasive red palm weevil, Rhynchophorus ferrugineus (Olivier), has become the major pest of palms in the Mediterranean Basin. Chemical control against this species is difficult because of its cryptic habits and is mainly based on the repeated application of large quantities of synthetic insecticides. The aim of this work has been to evaluate in the field the efficacy of imidacloprid (Confidor 240 OD) and Steinernema carpocapsae Weiser with chitosan (Biorend R Palmeras) as soil and stipe treatments respectively, alone or in combination, against this pest. RESULTS All treatments significantly reduced the mean number of immature stages of R. ferrugineus per palm. However, there were no significant differences among the different treatments considered. Efficacies ranged from 83.8 to 99.7% for the mean number of immature stages found in the palms and resulted in a significant increase in palm survival compared with the untreated control (75.0-90.0% versus 16.5% respectively). CONCLUSION Both imidacloprid and S. carpocapsae in a chitosan formulation proved highly effective against R. ferrugineus in the field, and their efficacies did not significantly change when used in combination.