INFLUENCE OF TEMPERATURE ON THE REPRODUCTIVE POTENTIAL OF TWO MITE PREDATORS OF THE TWO-SPOTTED SPIDER MITE

Abstract

Oviposition of the predacious mites Phytoseiulus persimilis and Typhlodromus fallacis began 2 days after mating, reached a peak in 1 week, and then declined irregularly. The rates of oviposition were higher, and the oviposition period shorter at 26° than at 20°C. P. persimilis laid 47% more eggs than T. fallacis. The generation time for both species was very dependent on temperature. Minimum values of 112 hours for P. persimilis and 127 hours for T. fallacis were obtained at 28°.Calculations of potential predator populations from the generation time, age-specific fecundity, and proportion of females were made on a daily basis for successive generations. The potential number of living females derived from one mated pair increased logarithmically after a few cycles representing new generations. The rate of increase of P. persimilis populations was 26% higher than that of T. fallacis, and in both species the rate at 26° was about double the rate at 20°.