Control of egg and neonate larvae of Xylotrechus arvicola (Coleoptera: Cerambycidae), a new vineyard pest, under laboratory conditions

Abstract

[EN] Background andAims: Xylotrechus arvicola (Coleoptera: Cerambycidae) is a newvineyard pest. Six insecticideswere tested on X. arvicola eggs arranged in Petri dishes and in two parts of the vine: branch and trunk. Method and Results: According to the Abbott formula, on Petri dishes, chlorpyrifos had total ovicidal control, significantly different from that of pyriproxyfen (88.3%), Beauveria bassiana (84.3%) and imidacloprid (80.9%). On branches, chlorpyrifos (91.6%), pyriproxyfen (79.1%) and flufenoxuron (75.0%) showed improved toxic effect, and on trunks, chlorpyrifos (83.3%) gave the best control, significantly different from that of imidacloprid (50.0%), pyriproxyfen (45.8%) and flufenoxuron (37.5%). Larval mortality was registered from the seventh to the fourteenth day after treatment: spinosad (50.0%), imidacloprid (45.8%) and B. bassiana (33.3%) were the insecticides that showed greater larval mortality on branches. These insecticides also showed greater larval mortality on trunks, but only B. bassiana (50.0%) had a greater residual effect on trunks than on branches. Conclusions: All insecticides evaluated gave better ovicidal control when applied directly on Petri dishes than when applied on branches and trunks, where all insecticides (except chlorpyrifos and imidacloprid) show greater toxic effect when applied on branches. Spinosad and B. bassiana have the best larval residual mortality, when applied, respectively, on branches and on trunks. Significance of the Study: Beauveria bassiana is the best insecticide with residual effect on neonate larvae on trunks, where the greater thickness of the rhytidome and cracks favoured the development of this fungus to invade actively the larvae through their shell and proliferate inside.