Different forms of Tetranychus urticae Koch and their plasticity in retaining eggs in the presence of predatory mites, Amblyseius swirskii and Phytoseiulus persimilis

Recent reports indicate that female prey species may increase the time to oviposition in order to prevent egg predation. The generality of this behavior is unknown especially among herbivorous mites. We used females of two forms of Tetranychus urticae, red and green forms, to study whether they retain eggs in response to exposure to the predatory mites Phytoseiulus persimilis and Amblyseius swirskii. Females were tested in two situations: 1) receiving cues related to predator-prey interaction; 2) perceiving the direct presence of predator. None of the treatments induced the T. urticae forms to retain eggs. The egg development time of the green form was significantly shorter than that of the red form after receiving cues related to P. persimilis-prey interactions. The egg development time of the forms did not show significant difference in the direct presence of each of the predator species. The probability of hatching plasticity in T. urticae is discussed