AGE-STAGE, TWO-SEX LIFE TABLE OF Tetranychus urticae KOCH (ACARI: TETRANYCHIDAE) REARED ON FIVE COTTON VARIETIES

Abstract

Tetranychus urticae Koch (Acari: Tetranychidae) is an important cotton pest in Bangladesh and other cotton growing countries. The effect of five varieties of cotton (CB-12, CB-14, CB-15, HC-1 and M-1) on the life history and demographic parameter of T. urticae studied at 25 ± 2°C temperature, 50-70% RH and a photoperiod of 16:8 h (L:D). The life history parameters were estimated using the age-stage, two-sex life table method. The shortest female development time was (15.00 days) on the M-1 variety and the longest (16.17 days) on the CB-15 variety. The T. urticae fecundity ranged from 24.66 to 16.87 eggs/ female, with the CB-15 variety having the highest and the HC-1variety having the lowest values. The shortest female longevity was observed on the CB-12 variety (26.55 days) and the longest on the CB-15 variety (32.24 days). The net reproductive rate (R0) varied from 12.16 on HC-1 to 18.33 eggs per individual on the CB-15 variety. The finite rate of increase (λ) was highest on the M-1 variety (1.1362 days) and lowest on the HC-1 variety (1.1146 days). The lowest (0.1085 day) value of the intrinsic rate of increase (rm) was on the HC-1 variety and the highest was on the M-1 variety (0.1277 days). The mean generation time (T) was lowest (22.05 days) on the M-1 variety and highest (26.05 days) on the CB-14 variety. This finding indicates that the HC-1 variety is a less suitable variety for T. urticae than the other tested varieties. Therefore, this study provides new information for developing a comprehensive integrated pest management plan for T. urticae on cotton