Functional and numerical response comparison of Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) to Frankliniella occidentalis (Pergande) and Tetranychus urticae Koch

Background The predatory mite Neoseiulus californicus (McGregor) is extensively utilized in biological control programs targeting various arthropod pests. Comprehending its quantitative predator-prey interactions is critical for enhancing release strategies within integrated pest management (IPM) systems. This investigation systematically quantified and contrasted the functional and numerical responses of N. californicus to two economically significant pest species: the two-spotted spider mite Tetranychus urticae Koch and the western flower thrips Frankliniella occidentalis (Pergande), across the egg and first-instar larval stages under meticulously controlled laboratory conditions. Functional response parameters were derived utilizing Holling's disc equation, numerical responses were quantified through oviposition assessments, and an integrated Performance Index combing both metrics was computed. Results Neoseiulus californicus exhibited a Type II functional response to all prey stages (R² = 0.955–0.994). While attack rates were higher for T. urticae (0.72–0.76 day⁻¹) than for F. occidentalis (0.45–0.59 day⁻¹), the most pronounced difference was in handling time, which was 7.6–9.3× shorter for spider mites (3.7–3.9 minutes) than for thrips (29.5–34.7 minutes). Consequently, maximum theoretical predation rates reached 370–385 prey day⁻¹ for T. urticae versus only 41–49 for F. occidentalis . At operationally relevant densities (15–30 prey/arena), predation efficiency averaged 72.4% for spider mites compared to 53.5% for thrips. The numerical response mirrored these trends, with oviposition 1.39× higher on T. urticae (2.50 ± 0.27 eggs female⁻¹ day⁻¹) than on F. occidentalis (1.80 ± 0.22). An integrated Performance Index was 2.89× higher for spider mites, with optimal deployment densities identified at 18.7 and 22.3 prey per arena, respectively. Life stage effects were negligible, though predator interference reduced per capita consumption by 61% at high densities. Conclusion N. californicus shows superior biological control potential against T. urticae compared to F. occidentalis , due to efficient prey handling and enhanced reproduction. We recommend its use as a primary control agent for spider mite at predator:prey ratios of at 1:6–1:10. For thrips, F. occidentalis , should be integrated with complementary methods. These findings provide quantitative guidance for optimizing release strategies in IPM programs.