Predation on and discrimination between con- and heterospecific eggs among specialist and generalist phytoseiid mites (Acari: Phytoseiidae)

We studied predation on and discrimination between con- and heterospecific eggs among adult females and immatures of 13 phytoseiid mite species of different feeding types. Species ranged from specialized predators that feed on densely webbing spider mites (specialists) to polyphagous predators that feed on various kinds of animal and nonanimal food (generalists). Four of 9 generalists, including Neoseiulus californicus (McGregor), Amblyseius andersoni Chant, Neoseiulus fallacis (Garman), and Neoseiulus cucumeris (Oudemans), fed on phytoseiid eggs and preferred heterospecifics versus conspecifics. Their immatures completed development and adult females sustained oviposition by feeding exclusively on phytoseiid eggs, mainly heterospecifics. Also, 2 of 4 specialists, including Galendromus occidentalis (Nesbitt) and Phytoseiulus persimilis Athias-Henriot, accepted phytoseiid eggs as prey but did not discriminate eggs of their own from those of other species. P. persimilis and G. occidentalis suffered high juvenile mortality, and oviposition was negligible when they fed on phytoseiid eggs. Among species that fed on greater than or equal to 1 egg per female per day, generalists showed higher predation rates on heterospecific eggs than did specialists; on conspecific eggs, the results were reversed. Euseius finlandicus (Oudemans), Neoseiulus longispinosus (Evans), Phytoseiulus macropilis (Banks), Neoseiulus barkeri (Hughes), Euseius hibisci (Chant), Typhlodromus pyri Scheuten, and Kampimodromus aberrans (Oudemans) were less attracted to phytoseiid eggs as food.