title: Long-term foliar persistence and efficacy of spinosad against beet armyworm under greenhouse conditions.
abstract: BACKGROUND
  The immediate lethality caused by spinosad has been widely studied on Spodoptera exigua (Hübner). However, long-term effects can also provide valuable information on insecticide toxic action. Here, the persistence of spinosad on Capsicum annuum L. foliage and the lethal and sublethal effects of greenhouse-aged foliar residues of this insecticide on third instars of S. exigua are reported.
  
  
  RESULTS
  Foliage was collected at 0, 3, 5, 10, 20, 30, 40 and 50 days after application, and spinosad residues were measured. Residues decreased over time according to first-order kinetics. The average rate constant and half-life of disappearance were 4.44 × 10(-3) and 156 days and 5.80 × 10(-3) and 120 days for 60 and 120 mg L(-1) respectively. Larval mortality gradually decreased, corresponding to the residues, but was still appreciable (35 and 65% for 60 and 120 mg L(-1) respectively) when the larvae were fed with foliage collected 50 days after treatment. Subsequently, pupal development was reduced and varied between 20 and 60% and between 21 and 41% for 60 and 120 mg L(-1) , respectively, in all ages of leaf residues that were bioassayed. At all time points, the consumption rate by the larvae was reduced between 62 and 84% for both concentrations that were bioassayed.
  
  
  CONCLUSIONS
  It is concluded that, under the present greenhouse conditions, the degradation of spinosad was slower than that reported by other authors in the field, and, because of that, its residues could cause lethal and sublethal effects to S. exigua larvae.
authors.affiliation: Instituto de Investigaciones Agropecuarias y Forestales, Universidad Michoacana de San Nicolás de Hidalgo, Tarímbaro, Michoacán, Mexico.
authors.forename: Erika L
authors.initials: EL
authors.lastname: Sántis
authors.forename: Luis A
authors.initials: LA
authors.lastname: Hernández
authors.forename: Ana M
authors.initials: AM
authors.lastname: Martínez
authors.forename: Jesús
authors.initials: J
authors.lastname: Campos
authors.forename: José I
authors.initials: JI
authors.lastname: Figueroa
authors.forename: Philippe
authors.initials: P
authors.lastname: Lobit
authors.forename: Juan M
authors.initials: JM
authors.lastname: Chavarrieta
authors.forename: Elisa
authors.initials: E
authors.lastname: Viñuela
authors.forename: Guy
authors.initials: G
authors.lastname: Smagghe
authors.forename: Samuel
authors.initials: S
authors.lastname: Pineda
mesh_terms: D000818:Animals; D001681:Biological Assay; D002212:Capsicum / Q000254:growth & development; D004338:Drug Combinations; D004780:Environment, Controlled; D007300:Insect Control / Q000379:methods*; D007306:Insecticides / Q000737:chemistry; D007700:Kinetics; D018942:Macrolides / Q000737:chemistry; D010573:Pesticide Residues / Q000032:analysis; D018515:Plant Leaves / Q000254:growth & development; D018411:Spodoptera / Q000502:physiology*; D013997:Time Factors
chemical_list: D004338:Drug Combinations; D007306:Insecticides; D018942:Macrolides; D010573:Pesticide Residues; C415329:spinosad