title: Resistance to spinosad in the western flower thrips, Frankliniella occidentalis (Pergande), in greenhouses of south-eastern Spain.
abstract: Susceptibility to spinosad of western flower thrips (WFT), Frankliniella occidentalis (Pergande), from south-eastern Spain was determined. LC(50) values of the field populations without previous exposure to spinosad collected in Murcia in 2001 and 2002 ranged from 0.005 to 0.077 mg L(-1). The populations collected in Almeria in 2003 in greenhouses were resistant to spinosad (LC(50) > 54 mg L(-1)) compared with the authors' highly susceptible laboratory strain. The highly sensitive laboratory strain leads to very high resistance ratios for the field populations (>13 500), but these ratios do not necessarily mean resistance problems and control failures (spinosad field rate 90-120 mg L(-1)). The populations collected in Murcia from some greenhouses in 2004 were also resistant to spinosad (RF > 3682). Spinosad overuse, with more than ten applications per crop, produced these resistant populations in some greenhouses. Spinosad showed no cross-resistance to acrinathrin, formetanate or methiocarb in laboratory strains selected for resistance towards each insecticide. Correlation analysis indicated no cross-resistance among spinosad and the other three insecticides in 13 field populations and in nine laboratory strains. The synergists piperonyl butoxide (PBO), S,S,S-tributyl phosphorotrithioate (DEF) and diethyl maleate (DEM) did not enhance the toxicity of spinosad to the resistant strains, indicating that metabolic-mediated detoxification was not responsible for the spinosad resistance. These findings suggest that rotation with spinosad may be an effective resistance management strategy.
authors.affiliation: Departamento de Producción Vegetal, Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain. pablo.bielza@upct.es
authors.forename: Pablo
authors.initials: P
authors.lastname: Bielza
authors.forename: Vicente
authors.initials: V
authors.lastname: Quinto
authors.forename: Josefina
authors.initials: J
authors.lastname: Contreras
authors.forename: María
authors.initials: M
authors.lastname: Torné
authors.forename: Alberto
authors.initials: A
authors.lastname: Martín
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Espinosa
mesh_terms: D000818:Animals; D004338:Drug Combinations; D007313:Insecta / Q000502:physiology*; D007305:Insecticide Resistance / Q000502:physiology; D007306:Insecticides; D018942:Macrolides; D013030:Spain
chemical_list: D004338:Drug Combinations; D007306:Insecticides; D018942:Macrolides; C415329:spinosad