title: Effects of two biorational insecticides, spinosad and methoxyfenozide, on Spodoptera littoralis (Lepidoptera: Noctuidae) under laboratory conditions.
abstract: The toxicity of two biorational insecticides, spinosad (Tracer) and methoxyfenozide (RH-2485), was tested against eggs, larvae, and pupae of the noctuid Spodoptera littoralis (Boisduval). In the first experiment, filter paper circles containing egg masses of two different age classes, young (<24 h old) and old (24-48 h old), were dipped in different concentrations of each insecticide diluted in either water or acetone. No ovicidal activity was recorded when insecticides were diluted in water. In contrast, when insecticides were diluted in acetone, both egg age classes generally showed a concentration-dependent response for both compounds. Mortality of larvae that hatched from both egg age classes was significantly increased, compared with control larvae, at all concentrations of both insecticides when diluted in water or acetone alike. The prevalence of mortality was similar with each insecticide. In the second experiment, third instars of S. littoralis were fed semisynthetic diet containing different concentrations of both insecticides. According to LC50 values, no significant differences were observed between spinosad (2.11 mg [AI]/kg diet) and methoxyfenozide (3.98 mg [AI]/kg diet) after 48 h of treatment, based on the overlap of 95% CL. Toxic effects on the mortality of pupae, adult emergence, and the prevalence of deformed adults after topical application on young pupae also were examined. Only methoxyfenozide caused pupal mortality and deformed adults. Our results suggest that spinosad and methoxyfenozide are potentially potent compounds for control of S. littoralis.
authors.affiliation: Instituto de Investigaciones Agropecuarias y Forestales, Universidad Michoacana de San Nicholás de Hidalgo, Km. 9.5 Carr. Morelia-Zinapécuaro, 58880 Tarímbaro, Michoacán, Mexico.
authors.forename: Samuel
authors.initials: S
authors.lastname: Pineda
authors.forename: Flor
authors.initials: F
authors.lastname: Budia
authors.forename: Marcela Inés
authors.initials: MI
authors.lastname: Schneider
authors.forename: Antonio
authors.initials: A
authors.lastname: Gobbi
authors.forename: Elisa
authors.initials: E
authors.lastname: Viñuela
authors.forename: Javier
authors.initials: J
authors.lastname: Valle
authors.forename: Pedro
authors.initials: P
authors.lastname: Del Estal
mesh_terms: D000818:Animals; D004338:Drug Combinations; D006834:Hydrazines / Q000008:administration & dosage*; D007306:Insecticides / Q000008:administration & dosage*; D007605:Juvenile Hormones / Q000008:administration & dosage*; D007814:Larva; D018942:Macrolides / Q000008:administration & dosage*; D010063:Ovum; D010209:Paper; D011679:Pupa; D018411:Spodoptera / Q000254:growth & development
chemical_list: D004338:Drug Combinations; D006834:Hydrazines; D007306:Insecticides; D007605:Juvenile Hormones; D018942:Macrolides; C406712:methoxyfenozide; C415329:spinosad