Susceptibilidad de Frankliniella occidentalis (Thysanoptera: Thripidae) a Insecticidas en la Zona Central de Chile
A B S T R A C T Susceptibility of the California thrips, Frankliniella occidentalis (Pergande) to formetanate (Dicarzol 500 SP), methamidophos (Tamaron 600 SL), dimethoate (Perfekthion), and spinosad (Success 48) was evaluated using serial concentrations of insecticides sprayed on bean leaves with a Potter Tower. In the bioassays, adult females collected in three localities of the V th Region (Ocoa 32º55' S lat and 71º05' W long, 365 m.o.s.l.; Auco 32º52' S lat and 70º40' W long., 762 m.o.s.l.,
... ong., 762 m.o.s.l., and Vichiculén 32º52' S lat and 70º57' W long, 279 m.o.s.l.) were used. The results were submitted to a Probit analysis, and the resistance factors (FR) were calculated with lethal concentrations 50 (LC 50 ) of the most sensible strain to the four insecticides. The FRs obtained for spinosad were: 1, 1.3 and 1.5; to dimethoate 1, 1.6 and 7.4; to metamidophos 1, 1.5 and 4.2 and, to formetanate 1, 2 and 2, in Ocoa, Auco and Vichiculén, respectively. The Vichiculén strain had lowest susceptibility to all insecticides tested. For all strains, the response to spinosad showed the highest susceptibility. Recommendations to develop strategies to manage resistance of F. occidentalis to insecticides are discussed.