Author : Nguyen Duc Tung

Summary : The life table of N. longispinosus, which was studied at 30+-1 degrees C, 80+-5% relative humidity and with T. urticae as prey, show that the intrinsic rate of natural increase (rm) was 0.2719/female/day; the net reproductive rate (Ro) was 18.79; cohort generation time (Tc) was 12.178 days; the doubling time (DT) was 2.55 days; and the finite rate of increase of 1.31/female/day. All these demographic parameters indicate the capacity of N. longispinosus to increase in number within a short time relative to its prey. The most effective predator: prey ratio in the laboratory, greenhouse and field experiments were 1:33, 1:25 and 1:25, respectively. These ratios were found to suppress the pest mite population while maintaining the predatory mite population up to 25 days after release. These findings could provide basis of the timing and rate of predatory releases for mite control.