Life Table Characteristics of the Two Spotted Spider Mite Tetranychus urticae Koch treated with Certain Acaricides

Abstract

The experiment was carri ed out to estimate the sustainable effect of the acaricides, profenofos, hexythiazox and o:'i nomesifen on offspring of the two spotted spider mite Tetranychus urticae Koch. TI1e estimation was determined -> ing a combination of conventional bioassay of the tested acaricides and life table procedures of the two spotted spider ::1ite. LC25. LC50 and LC90 of profenofos recorded 3.64 , 9.90 and 66.82 ppm, respectively and 6.9, 20.68 and : 67.2 ppm , respectively for hexythiazox; whereas they were 10.46, 57 .5 and 455 .8 ppm,respectively for spinomesifen . The biological aspects, developmental time of mites treated with LC 50 of the tested acaricides, were followed up. Results show that the tested acaricides affected the developmental time of immature stages. Developmental time 2f untreated mites was achieved throughout 6.16 days; whereas it was 7.12, 7.36 and 8.88 days for mites treated 11 ith , profenofos, hexythiazox and spinomesifen, respectively. The tested acaricides showed slight effect on preoviposition period. Survivorship (Lx) varied in their chances to reach adulthood according to the tested acaricide. Fecundity (Mx), the gross reproductive rate (GRR) and net reproductive rate (Ro) were markedly affected by the acaricides. There were no significant differences on the hatchability percentages of laid eggs by treated and untreated femal es and among eggs that were laid at different time throughout the laying period. Data revealed that there were no significant differences among generation time (T) of treated and untreated females. Data showed that untreated mite have the highest intrinsic rate of increase (rm) 0.46 per individual per day; whereas the tested acaricides, profenofos, hexythiazox and spiromesifen enhanced negative intrinsic rate of increase -0.67, -0.74 and-0.7 per individual per day, respectively. Data also showed that the population of the untreated mite, as finite rate of increase (A.), increased daily by 1.58; whereas it was 0.51 , 0.48 and 0.5 times for treated mite with profenofos, hexythiazox or spiromesifen respectively.