Demography and Mass Rearing of Amblyseius swirskii (Acari: Phytoseiidae) Fed on Two Species of Stored-Product Mites and Their Mixture.

Amblyseius swirskii (Athias-Henriot) is one of the most important biological control agents and has been used in many countries. In this study, the suitability of Carpoglyphus lactis L. (Acari: Carpoglyphidae), Tyrophagus putrescentiae (Schrank), and their mixture for rearing A. swirskii was evaluated by using the two-sex life table. When reared on C. lactis, the durations of egg, deutonymph, total preadult, total preoviposition period, and adult male longevity of A. swirskii (1.95, 1.17, 6.13, 6.30, and 10.09 d, respectively) were significantly shorter than those reared on the mixed prey (2.05, 1.45, 6.55, 6.64, and 15.56 d, respectively). When reared on the mixed prey, however, the fecundity (110.21 eggs/female) of A. swirskii was significantly higher in comparison with those solely reared on C. lactis (82.17 eggs/female) or on T. putrescentiae (98.23 eggs/female). When reared on the mixed diet, the intrinsic rate of increase (r = 0.3792 d-1), finite rate of population increase (λ = 1.4611 d-1), and net reproductive rate (R0 = 79.69 offspring) of A. swirskii were significantly higher than those on single-species diets. For a daily production of 10,000 eggs of A. swirskii, a smaller population size (2,626 individuals) of A. swirskii is needed when reared on the mixed diet, in contrast to the 4,332 individuals on C. lactis and 3,778 individuals on T. putrescentiae. The population projection and mass-rearing analysis based on life table showed that the mixed diet was the most suitable and economical diet for the mass-rearing of A. swirskii.

Demographic traits of Tetranychus urticae (Acari: Tetranychidae) on leaf discs and whole leaves.

Life tables of twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), were studied on leaf discs and whole leaves of the common bean plant, Phaseolus vulgaris L. Data were analyzed based on the age-stage, two-sex life table theory. Durations of deutonymph stage, total preadult stage, and preoviposition period of mites reared on whole leaves (1.22, 7.6, and 0.29 d, respectively) were significantly shorter than those reared on leaf discs (1.73, 8.2, and 0.89 d, respectively). The lifetime fecundities were 22.81 and 12.05 offspring on whole leaves and leaf discs, respectively. Although hooked trichomes on the lower surface of the bean leaf contribute to adult mortality, spider mites successfully survive and reproduce on bean plants. The intrinsic rate of increase on whole leaves (0.235 d(-1)) was higher than that on leaf discs (0.159 d(-1). Higher intrinsic rate and fecundity found in mites reared on whole leaves may be due to the higher nutritional quality of whole leaves over leaf discs. We suggest that whole leaves should be used in future studies to better simulate realistic life history characteristics. The advantages of using age-stage, two-sex life tables over female age-specific life tables are discussed.