Effect of a heterospecific predator on the oviposition behavior of Phytoseiulus persimilis

Oviposition rate is affected by several factors such as con- and heterospecific competitors, food availability and patch quality. When the species have interacted for a sufficient period of time, the predator could profit from the ability to associate odors from the competitor with the risk of its eggs being attacked or eaten by that competitor. We examined the oviposition rate of Phytoseiulus persimilis for a response for signals emanating from its heterospecific competitor, Frankliniella occidentalis in the presence of their shared prey, Tetranychus urticae on rose and bean leaf patches. In the treatments in which the predatory mite and thrips were exposed to each other, a significant reduction was observed in the number of deposited eggs compared to the control experiment. The same result was found in an experiment in which the exposure time was limited to the pre-oviposition period of the predatory mite. Increasing the time elapsed since the two competitors were exposed to each other to 2 days, the effect of thrips on the oviposition rate of the predatory mite had vanished and approached the oviposition rate in the control experiment. The plant species used as a substrate for the interspecific interactions did not significantly alter the results. We discuss the potential consequences of the presence of thrips for the ability of P. persimilis to control the two spotted spider mite.