The preferred prey of P. persimilis is spider mites (family Tetranychidae), particularly Tetranychus species. Development and survival is normally reduced if it feeds on mites outside of this genus. An exception is Oligonychus pratensis (Banks) (Banks grass mite). Under laboratory conditions, P. persimilis females fed on all prey stages and their oviposition rate was similar to that with T. cinnabarinus as food. Unlike other species of the genus, but like Tetranychus species, O. pratensis spins quite dense webbing and mainly feeds on the undersurface of leaves. Development was also completed on a diet of cyclamen mites (Phytonemus pallidus, family Tarsonemidae). When given only larvae of the western flower thrips (Frankliniella occidentalis) (Insecta: Thysanoptera) as food, most nymphs developed to adults, but none of the females laid eggs. The use of food other than spider mites in natural conditions is thought to be rare, but could help to ensure survival when Tetranychus prey is scarce. Females die within a few days in the absence of food, but survival increases as the temperature decreases (five to 10 days at 20°C, over a month at 5-10°C). The availability of water also extends life when starved.
Males reach peak prey consumption soon after moulting to the deutonymph, feeding rate increases in the female until oviposition starts. At 25°C and 60 per cent relative humidity (R.H.), immatures needed to feed on a minimum of seven and an average of 14 spider mite eggs to reach adulthood. At 22°C and 60 per cent R.H., females needed at least five and an average of 8.5 eggs to produce an egg. Females spend most of their food (up to 70 per cent) on egg production. With a choice of all prey stages, proto- and deutonymphal P. persimilis fed mostly on spider mite eggs, but also took larvae and protonymphs. In low prey densities, adult females fed on all prey stages, but as density increased, consumed a greater number and proportion of eggs. Adult prey was eaten least.
Little is known about the identity and impact of natural predators of P. persimilis. Both the predatory bug Orius laevigatus (Insecta: Hemiptera) and its target thrips prey Frankliniella occidentalis were seen to feed on P. persimilis in laboratory experiments. However, mite numbers were evidently not affected on cucumber plants grown under glass, possibly due to the greater opportunites for escape.
(Laing, 1968; Takafuji and Chant, 1976; Moraes and McMurtry, 1985; Sabelis, 1985a, d; Pickett and Gilstrap, 1986; McMurtry and Rodriguez, 1987; McMurtry and Croft, 1997; Venzon et al., 2001; Walzer et al., 2004; Vanas et al., 2006)