Comparative life histories and predation types: are Neoseiulus californicus and N. fallacis (Acari: Phytoseiidae) similar type II selective predators of spider mites?

Both Neoseiulus californicus (McGregor) and N. fallacis (Garman) have been rated a type II selective predator of spider mites that feeds more on spider mites than pollen or insects. We assessed this predation rating or an alternative hypothesis that N. californicus is more of a generalist predator than N. fallacis. In tests, reproduction was equal or greater for N. californicus than N. fallacis when each was held separately with excess Tetranychus urticae Koch, Panonychus ulmi (Koch), Frankliniella occidentalis (Pergrande), or maize pollen, but it was less when with Aculus schlectendali Nalepa or Oligonychus ilicis (McGregor). N. californicus had other traits more like those of a generalist predator--adult females had shorter dorsocentral setae and moved farther on a plant but less often and for less distance between plants. N. californicus nymphs fed more either intraspecifically and interspecifically on phytoseiid eggs, but adult females of both species fed similarly on eggs of either phytoseiids. Larval feeding was less for N. californicus but nymphal feeding drive was alike for both species. Of 17 traits that were tested, 11 indicated more of a generalist role for N. californicus; 6 traits did not differ between species, and none indicated that N. californicus was more of a specialist predator of spider mites than N. fallacis. N. fallacis clearly is a specialist type II species, but a rating between specialist II and generalist III is needed for N. californicus. Traits of immatures were more discriminating than traits of female adults in this study; both trait types should be included in predation rating systems