Comparative Studies on Neoseiulus fallacis1 and Metaseiulus occidentalis1 for Azinphosmethyl Toxicity and Effects of Prey and Pollen on Growth2

Abstract

Two species of phytoseiid mites, Neoseiulus fallacis (Garman) and Metaseiulus occidentalis (Nesbitt), were subjected to toxicological and feeding tests. Results of toxicological tests showed that resistant and susceptible strains of M. occidentalis exhibited a greater degree of resistance to azinphosmethyl than the respective strains of N. fallacis. Feeding tests showed that immature N. fallacis grew faster to the adult than M. occidentalis when fed eggs of either the twospotted spider mite, Tetranychus urticae Koch, or the European red mite, Panonychus ulmi (Koch). Survival from larval to adult stage was similar for the two phytoseiid species when fed eggs of the twospotted spider mite. However, survival of M. occidentalis fed eggs of the European red mite was only 42.9% as compared with 74.3% for N. fallacis. Survival of M. occidentalis was increased to 80.0% when fed all developmental stages of the European red mite. Results of feeding-preference tests showed that the immature phytoseiids preferred eggs of the twospotted spider mite over European red mite eggs, but the adult phytoseiids preferred adult European red mites over adult twospotted spider mites. Growth and survival of N. fallacis fed pollen from the trumpet creeper vine, Campsis radicans Seem or tulip popular, Liriodendron tulipifera L., for the parent generation were similar to those obtained when fed twospotted spider mite eggs.