Activity levels of genetically manipulated and wild strains of Metaseiulus occidentalis (Nesbitt) (Acarina: Phytoseiidae) compared as a method to assay quality

The activity levels (AL) of males and females of four genetically manipulated strains and one wild strain of the phytoseiid Metaseiulus occidentalis (Nesbitt) were measured using a computerized video-tracking system. Such AL measurements offer the potential for a quantitative laboratory technique to evaluate the relative quality of strains. Adult females of a Permethrin-Organophosphorous-resistant (P-R) strain consistently had an average AL significantly lower than those of the Wild strain and of the three other laboratory strains. The low activity of the P-R strain is unlikely to be due to decreased strain quality associated with laboratory rearing procedures per se, because the three other long-established laboratory strains exibited AL averages comparable to the Wild strain. Adult males exibited no differences in AL. Possible reasons for the lower AL of the P-R strain are discussed.