title: Effects of spirodiclofen on reproduction in a susceptible and resistant strain of Tetranychus urticae (Acari: Tetranychidae).
abstract: In this study the reproductive capacity of a laboratory-selected spirodiclofen resistant strain was investigated after treatment with spirodiclofen. Firstly, females were exposed to different concentrations of spirodiclofen (200 and 1,000 mg/l) during 6, 12 or 24 h. In contrast to the susceptible parental strain, the fecundity and fertility of resistant mites was not affected by treatment with these concentrations after any time of exposure tested. Secondly, pre-treatment of the resistant females with the synergists PBO or DEF could increase the inhibitory effect of spirodiclofen on reproduction, demonstrating the possible involvement of monooxygenases and esterases in metabolic detoxification of the acaricide. Because spirodiclofen interferes with lipid biosynthesis, total lipid content was measured in female adults. There were no significant differences between treated and non-treated female adults, both in the susceptible and resistant strain. However, the total lipid content in the resistant females was significantly higher than in susceptible females. Our data shows that the detection of spirodiclofen resistance should not be limited to mortality bioassays with eggs or larvae, but should be combined with inhibitory studies on female fertility and fecundity.
authors.affiliation: Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: Van Pottelberge
authors.forename: Jahangir
authors.initials: J
authors.lastname: Khajehali
authors.forename: Thomas
authors.initials: T
authors.lastname: Van Leeuwen
authors.forename: Luc
authors.initials: L
authors.lastname: Tirry
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000633:toxicity; D000818:Animals; D004351:Drug Resistance / Q000235:genetics; D005260:Female; D005298:Fertility / Q000187:drug effects; D005838:Genotype; D050356:Lipid Metabolism / Q000187:drug effects; D010574:Pesticide Synergists / Q000494:pharmacology; D010575:Pesticides / Q000633:toxicity*; D013141:Spiro Compounds / Q000633:toxicity*; D040102:Tetranychidae / Q000187:drug effects* / Q000235:genetics; D013997:Time Factors
chemical_list: D010574:Pesticide Synergists; D010575:Pesticides; D013141:Spiro Compounds; C508135:spirodiclofen; D015107:4-Butyrolactone