Biology, life table, and predation of Zetzellia mali (Acari: Stigmaeidae) on Tetranychus urticae (Acari: Tetranychidae)

Abstract

Biology, life table parameters and predation rate of the predatory mite Zetzellia mali (Ewing) (Acari: Stigmaeidae) feeding on eggs of Tetranychus urticae Koch (Acari: Tetranychidae) on apple leaves were studied at 25±1oC, 65±5% RH and a photoperiod of 16:8 (L:D) hours. The following average parameters were obtained: Female longevity is 10±0.73 days, fecundity is 1.42 eggs/female/day, egg mortality is 21%, preoviposition period is 1.81±0.2 days, oviposition period is 5.4±0.6 days, post oviposition period is 1.3±0.4 days, juvenile development time is 12.18±0.34 days, juvenile mortality is 22%, sex ratio is 0.72 (female/female plus male). Life table parameters were estimated as net reproductive rate (R0) 7.25, intrinsic rate of increase (rm) 0.146 days-1, finite rate of increase (я) 1.15, mean generation time (T) 12.88 days and doubling time (DT) 4.71 days. Average daily pre- dation of Z. mali females on T. urticae eggs was 3.14. Thus it is concluded that Z. mali can be considered as a valuable addition to the existing IPM methods for spider mites control.