Sterilization makes a difference: demographic analysis of spirodiclofen effects on Tetranychus urticae (Acari: Tetranychidae)

Spirodiclofen is characterized by a relatively slow acaricidal action against adult females of the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), with reduction their fecundity (eggs laid/female) and fertility hatched/female). Exposure pre-ovipositing T. to acaricide may affect population growth, considering that high reproduction young crucial in biology this colonizing species. Effects spirodiclofen on life-history traits parameters were evaluated demographic bioassay using age-stage two-sex life table, constructed fecundity-based fertility-based variants. The was applied series nine concentrations, starting from recommended field rate (96 mg/l). treatments concentrations ranging 12 - 96 mg/l significantly reduced longevity, while 27 40% didn’t lay eggs. lethal 2 21% females, whom large majority A considerable part surviving also failed eggs within first four post-treatment days (when around 50% all control laid) i.e., they sterilized acaricide. At same time, percentage dead rose 17 55%, mainly due mortality females. three highest (24 – mg/l) net reproductive (R<sub>0</sub>), intrinsic increase (r) finite (λ), 49-72%, 20-34%, 4-6%, respectively, compared control. This result sterilization treated combination longevity ones. Application table showed significant decrease r λ (by 23-40%, 4-7%, control), concentrations. short-lived transovarial toxic effect observed not sufficient cause parameters, those acquired table.