title: Acaricidal and sublethal effects of a Chenopodium-based biopesticide on the two-spotted spider mite (Acari: Tetranychidae).
abstract: Acaricidal and sublethal effects of the biopesticide Requiem®EC (containing an essential oil extract of Chenopodium ambrosioides near ambrosioides) on the two-spotted spider mite, Tetranychus urticae Koch, were evaluated in laboratory bioassays. The biopesticide was applied to bean leaves or leaf discs using a Potter spray tower. Acaricidal activity against eggs and immatures was evaluated in successive acute toxicity bioassays. Concentration-mortality data were subjected to probit analysis and the following LC50values (ml/l) were calculated: 2.47 (eggs), 0.71 (larvae), 1.13 (protonymphs), 2.23 (female deutonymphs), and 6.02 (female teleiochrysalises). In adult bioassay, in which pre-ovipositional females were treated with a series of concentrations (0.31-10 ml/l), a run-off effect ranging 4-80% (after 24 h) and 8-93% (after 72 h) was observed. In two-choice bioassay, T. urticae females preferred the untreated halves of leaves over the halves treated with 1.25-10 ml/l biopesticide and they laid significantly more eggs on the untreated halves in the first 24 h and summed over 72 h. The indices of repellency and oviposition deterence ranged 11.2-77.3 and 14.8-87.9%, respectively. In age-stage two-sex life table bioassay, the females that hatched from eggs treated with 2.5 ml/l biopesticide and reached adulthood on treated leaf surface showed a significantly reduced the intrinsic rate of increase (r = 0.222), compared to the control (r = 0.317). The reduction of population growth was mainly due to a reduced preadult survival rate (0.42 ± 0.04) and extended juvenile developmental time (9.27 ± 0.11 days), compared to the control (0.93 ± 0.03 and 7.70 ± 0.06 days, respectively).
authors.affiliation: Faculty of Biology, University of Belgrade, Studentski trg 16, Belgrade, 11000, Serbia.|Department of Applied Entomology, Institute of Pesticides and Environmental Protection, Banatska 31B, P.O. Box 163, Belgrade, 11080, Serbia.
authors.forename: Asma
authors.initials: A
authors.lastname: Musa
authors.affiliation: Department of Applied Entomology, Institute of Pesticides and Environmental Protection, Banatska 31B, P.O. Box 163, Belgrade, 11080, Serbia.
authors.forename: Irena
authors.initials: I
authors.lastname: Međo
authors.affiliation: Department of Applied Entomology, Institute of Pesticides and Environmental Protection, Banatska 31B, P.O. Box 163, Belgrade, 11080, Serbia.
authors.forename: Ivana
authors.initials: I
authors.lastname: Marić
authors.affiliation: Department of Applied Entomology, Institute of Pesticides and Environmental Protection, Banatska 31B, P.O. Box 163, Belgrade, 11080, Serbia. dejan.marcic@pesting.org.rs.
authors.forename: Dejan
authors.initials: D
authors.lastname: Marčić
mesh_terms: D056810:Acaricides / Q000494:pharmacology*; D000818:Animals; D061046:Biological Control Agents / Q000494:pharmacology*; D027462:Chenopodium / Q000737:chemistry*; D005260:Female; D010058:Oviposition; D040102:Tetranychidae / Q000187:drug effects*
chemical_list: D056810:Acaricides; D061046:Biological Control Agents
keywords: Behavior; C. ambrosioides; Life tables; Reproduction; T. urticae; Toxicity