Comparative studies on four strains of Typhlodromus occidentalis Nesbitt (Acarina: Phytoseiidae). IV. Life history studies

摘要

The life histories of strains of T. occidentalis from Washington, Utah, and California (2) were studied under laboratory conditions. No appreciable differences were found between the 4 strains in comparisons of developmental rates, oviposition rates throughout the oviposition period, total egg production, host stage preferences, and host mite consumption and corresponcling daily oviposition rates. Behavioral characteristics of the life stages of each subpopulation also were not markedly different. Certain morphological features, the frequency of cannibalism, and the sex ratios from progeny of laboratory reared mites differecl between the strains exarnined. Northern populations exhibited longer dorsal setae, longer peritremes, larger dorsal shield, and a reduced frequency of cannibalism when compared to populations from southem California. The Utah strain showed a lower sex ratio of femalesfmales compared with ratios obtainecl from Washington and California predators. Explanations are proposecl to account for certain life history differences which have been reported in the literature for this species.