Preference behavior of Phytoseiulus persimilis and Neoseiulus californicus affected by heterospecific predators

The initial phase in optimizing the efficacy of multiple predators in biocontrol programs involves elucidating their reactions in the presence of heterospecific competitors. Predators sharing the same trophic level may interfere with one another through competition for food resources and engage in internal predation dynamics. This study explored the compatibility of two predatory mite species, Phytoseiulus persimilis, and Neoseiulus californicus, as biocontrol agents targeting Tetranychus urticae. Plants with prey and those with prey plus heterospecifics were used to assess the preference of adult females of the predatory mite competitors. Our results indicated no significant preference by either predatory mite species for plants with spider mites alone or alongside heterospecifics. Additionally, the fecundity rates of both species remained unaffected by the presence of heterospecifics. Notably, N. californicus strongly preferred aggregating eggs on the side with spider mite webs, contrasting with the more random distribution of P. persimilis eggs, although the distribution of eggs on leaf discs was altered in the presence of higher densities of heterospecifics. The total number of eggs of each predator species remained unaffected by the presence of heterospecifics. While our findings suggest compatibility between P. persimilis and N. californicus, which could enhance their combined use in pest management, further field studies are necessary to validate this potential under diverse environmental conditions and pest densities.