Temperature-dependent development of Neoseiulus barkeri (Acari: Phytoseiidae) on Tetranychus urticae (Acari: Tetranychidae) at seven constant temperatures

The effect of seven constant temperatures of 15, 20, 25, 27, 30, 35 and 37 degrees C on developmental time of Neoseiulus barkeri Hughes were determined in laboratory conditions under 65%+/- 5% RH and a photoperiod of 12 : 12 (L : D) h on nymphal stages of Tetranychus urticae Koch. Total developmental time of females (from egg to adult emergence) at the above-mentioned temperatures was 26.59, 14.43, 6.32, 5.64, 4.59, 3.98 and 4.67 days, respectively. Developmental rate of the N. barkeri increased as temperature increased from 15 to 35 degrees C, but declined at 37 degrees C. A linear and two nonlinear models were fitted to developmental rate of immature stages of N. barkeri to predict the developmental rate as a function of temperature, as well as to estimate the thermal constant (K) and critical temperatures (i.e., Tmin, Topt and Tmax). The estimated values of the Tmin and K for total developmental time using the linear model were 12.07 degrees C and 86.20 degree-days (DD), respectively. The Tmin and Tmax estimated by the Sharpe-Schoolfield-Ikemoto (SSI) model were 11.90 degrees C and 37.41 degrees C, respectively. The estimated Topt for overall immature stage development of N. barkeri by the Lactin and SSI models were 33.89 degrees C and 24.51 degrees C, respectively. Based on the biological criteria of model evaluation, the linear and SSI models were found to be the best models for describing the developmental rate of overall immature stages of N. barkeri and estimating the temperature thresholds.