Effect of flufenzine on population growth of Tetranychus urticae Koch (Acari: Tetranychidae)

Effect of flufenzine on different parameters of Tetranychus urticae Koch population growth was investigated. The parameters were computed based on the life tables of female survivors of treatment at different development stages (egg, larva, protonymph, deutonymph) with acaricide concentrations that had caused >90% mortality. The intrinsic rates of increase acquired by the so-called jackknife procedure (rj) from female treatment survovors at egg (rj = 0.237) and larva (rj = 0.220) stages had no significant statistical difference from the corresponding values in control (rj = 0.230). Female survovors of treatment at protonymph or deutonymph stages had 2.1 and 4.5 times lower net reproductive rate (R0) against the control while the corresponding rj values in treatment (0.204 and 0.171) were statistically significantly lower than the control (0.255). Treatment with flufenzine at protonymph and deutonymph stages significantly disturbed the age structure of the surviving part of population. The article discusses the significance of sublethal effects of flufenzine in advancement of the acaricide's application strategy in controlling T. urticae. U radu je ispitivan efekat flufenzina na parametre populacionog rasta Tetranychus urticae Koch, izracunatih na osnovu tablica zivota zenki prezivelih tretiranja u jednom od razvojnih stadijuma (jaje, larva protonimfa, deutonimfa) koncentracijama ovog akaricida koje su uzrokovale smrtnost > 90%. Vrednosti prirodne stope rasta populacije, dobijene tzv. "jackknife" postupkom (rj), zabelezene kod zenki koje su prezivele tretiranje u stadijumu jajeta (rj = 0.237) i larve (rj = 0.220) nisu se statisticki znacajno razlikovale od odgovarajuce vrednosti iz kontrole (rj = 0.230). Zenke koje su prezivele tretiranje kao protonimfe, odnosno deutonimfe, imale su 2.1, odnosno 4.5 puta manju neto stopu reprodukcije (Ro) u odnosu na kontrolu, dok su odgovarajuce rj vrednosti iz tretmana (0.204 i 0.171) bile statisticki znacajno nize od kontrole (0.255). Tretiranje flufenzinom u stadijumu protonimfe i deutonimfe znacajno je poremetilo uzrasnu strukturu prezivelog dela populacije. U radu se razmatra znacaj subletalnih efekata flufenzina za. poboljsanje strategije primene ovog akaricida u suzbijanju T. urticae.