DEVELOPMENT AND LIFE TABLE PARAMETERS OF TETRANYCHUS TURKESTANI (ACARINA: TETRANYCHIDAE) AT DIFFERENT CONSTANT TEMPERATURES

Selected life history characteristics of the strawberry spider mite (Tetranychus turkestani Ugarov and Nikolski, Acarina: Tetranychidae) were studied at four constant temperatures (15, 20, 25 and 30 degrees C). Egg-to-adult developmental time of females ranged from 50.11 +/- 0.79 days at 15 degrees C to 7.73 +/- 0.14 days at 30 degrees C. An average of 140.33 +/- 5.49 degree-days was required to complete development above the lower thermal threshold (11.89 degrees C). Preimaginal mortality was 62.92, 16.67, 41.82 and 42.31% at 15, 20, 25 and 30 degrees C, respectively. Mean longevity of female T. turkestani ranged from 30.22 +/- 2.88 days at 15 degrees C to 5.78 +/- 0.10 days at 30 degrees C. Mean total fecundity ranged from 23.11 +/- 3.14 to 49.95 +/- 5.54 eggs / female. The sex ratio (% females) ranged from 69.00 +/- 0.04 to 83.01 +/- 0.02%. The intrinsic rate of population increase (r(m)) ranged from 0.272 +/- 0.010 at 30 degrees C to 0.033 +/- 0.002 (female per female per day) at 15 degrees C. The population doubled most quickly at 30 degrees C (2.54 +/- 0.09 d) and most slowly at 15 degrees C (20.46 +/- 1.59 d). Based on these results, we can predict the presence of the different stages of the strawberry spider mite on cucumber over time. This information will therefore enable us to determine more precisely the best time to control this pest.