Biology and thermal requirement of Tetranychus ludeni Zacher on cotton leaves

Abstract

The objective of this work was to study the biology and thermal requirement of Tetranychus ludeni Zacher (Acari: Tetranychidae) on leaves of cotton (Gossypium hirsutum L. r. latifolium (Hutch)). Bioclimatic chambers at 20, 23, 25, 28 and 30^oC, relative humidity of 70±10%, and a 12 hours:12 hours (L:D) photoperiod were utilized. Development period of egg-adult, varied from 20.77 (20^oC) to 8.50 days (30^oC), for males and from 18.83 (20^oC) to 7.75 days (30^oC), for females. The threshold temperature of development, estimated by X intercession method for development period of egg-adult were 14.05^oC, for females and 13.91^oC, for males. While those values of thermal constant estimated by Réamur law were 138.34 day-degrees for females and 130.91 day-degrees for males. At 30^oC of temperature, the highest values of the intrinsic rate of increase (0.418), number of eggs/females/day (3.47), fecundity (61.29), reproductive rate net (48.00), and minimum value to the mean generation time (9.27) were shown.