Temperature influence on biology, thermal requirement and life table of the predatory mites Agistemus exsertus Gonzalez and Phytoseius plumifer (Can. & Fanz.) reared on Tetranychus urticae Koch

Abstract

The effect of temperature on the biology, thermal requirement and life table of Agistemus exsertus Gonzalez and Phytoseius plumifer (Can. & Fanz.) feeding on immatures of Tetranychus urticae Koch, was determined at four temperature degrees, i.e. 20, 25, 30 and 35°C. The total developmental durations of either predatory mite correlated negatively with increasing temperature. Minimum developmental thresholds (T o) of egg, larva, protonymph, deutonymph stages and life cycle of A. exsertus females averaged 0.95, 9.25, 7.80, 1.03 and 5.29 respectively, while those of P. plumifer females were 6.83, 9.35, 15.39, 15.40 and 13.22. On the other hand, A. exsertus and P. plumifer female required 416.66 and 126.58 DD, respectively, to reach adulthood. A. exsertus and P. plumifer net reproductive rate (R 0) averaged 16.13 and 8.23 then increased to 29.67 and 13.67 then sharply declined reaching 12.10 and 7.93 when the predator was kept at 20, 25 and 35°C, respectively. r m values of A. exsertus reached 0.06, 0.11, 0.12 and 0.13 reared at 20, 25, 30 and 35°C, respectively, while those of P. plumifer averaged 0.04, 0.11, 0.12 and 0.16. The doubling time (DT) of A. exsertus was 10.98, 6.10, 5.82 and 5.25, while that of P. plumifer averaged 15.93, 6.18, 5.70 and 4.35 at 20, 25, 30 and 35°C, respectively. Also, gross reproductive rate (GRR) of A. exsertus was 22.05, 51.70, 29.01 and 22.18, while that of P. plumifer averaged 12.67, 18.20, 18.40 and 11.82 at the same temperatures. The finite rate of increase in e rm values of either predator increased positively with increasing temperature degree.