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

Abstract

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 videotracking 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 exhibited AL averages comparable to the Wild strain. Adult males exhibited no differences in AL. Possible reasons for the lower AL of the P-R strain are discussed. Hungry adult females tested for AL exhibited three types of running patterns: edge, circle, and nonspecific. The Wild females ran mostly in circles, whereas the P-R females ran mostly near the edge. The males of the P-R and Wild strains did not run in circles, and displayed nearly equal proportions of the edge and nonspecific patterns. Pattern type appears to be related to rate of movement. A genetic analysis of AL was conducted using the Wild and P-R strains. The AL measurements of reciprocal F1 and F2 females indicated that the high AL of the Wild strain is dominant over the low AL of the P-R strain. Attempts to repeat the F1 and F2 tests were unsuccessful because of a previously undetected, one-way mating incompatibility between the reciprocal crosses; however, the data indicate that activity level is a heritable trait. PU - PUBLICATIONS UNIV CALIFORNIA PI - OAKLAND PA - AGR NATURAL RESOURCES 6701 SAN PABLO AVE, OAKLAND, CA 94608 USA