The effects of spiromesifen on life history traits and population growth of two-spotted spider mite (Acari: Tetranychidae).
Laboratory bioassays were conducted to evaluate the effects of spiromesifen on gross fecundity, gross fertility, net fertility and population growth of two-spotted spider mite (Tetranychus urticae Koch) after treatments with four acaricide concentrations: 180 mg/l, i.e. maximum recommended concentration for use in glasshouses against spider mites, 18, 1.8, and 0.18 mg/l, i.e. concentration discriminative for eggs and immatures in preliminary studies which produced 100% mortality of these stages. Quiescent female deutonymphs were treated in the first assay, and young pre-ovipositing females in the second and third, in which exposure lasted 6 h and 20 h, respectively. In the first assay, the 180, 18, and 1.8 mg/l concentrations significantly reduced gross fecundity (61-85%), gross fertility (64-87%) and net fertility (85-94%) of the surviving females. In the second one, only the highest concentration achieved a significant statistical reduction in gross fecundity (52%), gross fertility (67%) and net fertility (84%). In the third assay, fecundity and fertility reduction under the two highest concentrations was 98-99% and 93-98%, whereas it was 50-74% under the 1.8 mg/l concentration, and statistically different from control values. In all three trials, treatments with 180, 18, and 1.8 mg/l concentrations significantly reduced the instantaneous rate of increase. In the third assay, treatments with the two highest concentrations caused population decline. Sublethal activity of the 0.18 mg/l concentration was not found in any assay to be statistically significant. Sublethal effects of spiromesifen and its impact on T. urticae management are discussed.
Laboratory of Applied Entomology, Institute of Pesticides and Environmental Protection, Banatska 31B, P.O. Box 163, 11080 Belgrade-Zemun, Serbia. marcion@bitsyu.net
Dejan
D
Marcic
Irena
I
Ogurlic
Slavka
S
Mutavdzic
Pantelija
P
Peric
D056810:Acaricides / Q000494:pharmacology*; D000818:Animals; D005260:Female; D005298:Fertility / Q000187:drug effects; D052287:Oviparity / Q000187:drug effects*; D010571:Pest Control; D011158:Population Growth; D013141:Spiro Compounds / Q000494:pharmacology*; D040102:Tetranychidae / Q000187:drug effects*
D056810:Acaricides; D013141:Spiro Compounds; C521569:spiromesifen