Functional Response of Four Phytoseiid Mites to Eggs and First-Instar Larvae of Western Flower Thrips, Frankliniella occidentalis

The predation capacity and functional responses of adult females of the phytoseiid mites <i>Amblyseius largoensis</i> (Muma), <i>Proprioseiopsis lenis</i> (Corpuz and Rimando), <i>Paraphytoseius cracentis</i> (Corpuz and Rimando), and <i>Amblyseius swirskii</i> (Athias-Henriot) were studied on eggs and first instars of the western flower thrips, <i>Frankliniella occidentalis</i> (Pergande), in the laboratory at 25 °C and 30 °C. At both temperatures, the functional response of all four phytoseiid mites was type II to first instars of the thrips. In contrast, when offered thrips eggs, the functional response was type III. At both temperatures tested, <i>A. swirskii</i> had the highest mean daily consumption of first-instar <i>F. occidentalis</i>, followed by <i>A. largoensis</i>, <i>P. cracentis</i>, and <i>P. lenis</i>. <i>Amblyseius largoensis</i> had the shortest handling time and the highest maximum attack rate when first-instar thrips were the prey. When fed on thrips eggs, <i>A. largoensis</i> had the highest mean daily consumption, followed by <i>A. swirskii</i>, <i>P. cracentis</i>, and <i>P. lenis</i>. On thrips eggs, <i>A. swirskii</i> showed the shortest handling time and highest maximum attack rate. Our findings indicate that all four phytoseiids had a better ability to prey on first-instar larvae of <i>F. occidentalis</i> compared to thrips eggs. At 25 and 30 °C, <i>A. largoensis</i> was the better predator on thrips larvae, whereas <i>A. swirskii</i> was superior in consuming eggs of <i>F. occidentalis</i>. <i>Proprioseiopsis lenis</i> was the inferior predator on both thrips larvae and eggs compared to the other phytoseiids tested.