title: Threshold Concentration of Limonoids (Azamax) for Preventing Infestation by Mediterranean Fruit Fly (Diptera: Tephritidae).
abstract: This study identified the threshold concentration of limonoids for the complete inhibition of oviposition of Ceratitis capitata (Wiedemann) in grapes 'Itália.' Choice and no-choice experiments with the insect were performed. The three no-choice bioassays were conducted following a completely randomized design with 18 treatments (three densities of insects [one, two, or three females]×five concentrations of limonoids and control) and 20 replicates. In a free choice bioassay, two fruits per cage (a treatment grape and a control) were provided for ovipositing. Three densities of insects (one, two, or three females) were used, with 15 replicates. Bioassays were conducted at 25±2°C, 60±10% relative humidity, and a photoperiod of 14:10 (L:D) h. The inhibition of oviposition of C. capitata was concentration dependent, with infestation occurring at lower concentrations of azadirachtin (+3-tigloylazadirachtol) and complete inhibition occurring at concentrations at or exceeding 100 ppm azadirachtin (+28.5 ppm of 3-tigloylazadirachtol), maintaining protective effects even at the most densely populated treatment (three females per fruit). When the pest had a free choice of host grapes (treatment vs. control), severe inhibition was observed at concentrations≥50 ppm azadirachtin (+14.3 ppm of 3-tigloylazadirachtol). We conclude that a threshold concentration of 100 ppm azadirachtin (+28.5 ppm of 3-tigloylazadirachtol) is capable of preventing grape infestation. This concentration is likely to provide a reliable level of protection, as the experimental population density of three females per fruit usually does not occur in the field and wild flies usually have more host options.
authors.affiliation: Piaui State University, Fruit Fly Research Laboratory, CEP 64860-000, Uruçuí, PI, Brazil. Department of Entomology and Acarology, University of São Paulo, "Luiz de Queiroz" College of Agriculture, CP 9, CEP 13418-900, Piracicaba, SP, Brazil. silvamarcioalves@gmail.com.
authors.forename: M A
authors.initials: MA
authors.lastname: Silva
authors.affiliation: Piaui State University, Fruit Fly Research Laboratory, CEP 64860-000, Uruçuí, PI, Brazil.
authors.forename: G C D
authors.initials: GC
authors.lastname: Bezerra-Silva
authors.affiliation: Department of Entomology and Acarology, University of São Paulo, "Luiz de Queiroz" College of Agriculture, CP 9, CEP 13418-900, Piracicaba, SP, Brazil.
authors.forename: J D
authors.initials: JD
authors.lastname: Vendramim
authors.affiliation: Department of Chemistry, Federal University of São Carlos, CP 676, 13565-905, São Carlos, SP, Brazil.
authors.forename: M R
authors.initials: MR
authors.lastname: Forim
authors.affiliation: Department of Chemistry, Federal University of São Carlos, CP 676, 13565-905, São Carlos, SP, Brazil.
authors.forename: I C G
authors.initials: IC
authors.lastname: Sá
mesh_terms: D000818:Animals; D005260:Female; D007306:Insecticides / Q000008:administration & dosage*; D036701:Limonins / Q000008:administration & dosage*; D010058:Oviposition / Q000187:drug effects*; D011897:Random Allocation; D033621:Tephritidae
chemical_list: D007306:Insecticides; D036701:Limonins; C010329:azadirachtin; C476490:azadirachtin B
keywords: Mediterranean fruit fly; azadirachtin; fruit fly; natural product; neem