Is cattail pollen a sustainable long-term food source for the predatory mite, Euseius scutalis (Acari: Phytoseiidae)?

Studying multiple generations provides a more accurate and realistic understanding of how pollen affects phytoseiid mites over time. It is useful to assess potential negative effects on population dynamics, fitness, predatory behavior, and adaptation, which may not be apparent in a single-generation study. In this study, we investigated the effects of cattail pollen on the development, survival, and population growth of Euseius scutalis (Athias-Henriot) from the 1st to the 50th generations (G1–G50) to provide a comprehensive assessment of whether this pollen is a long-term viable diet for E. scutalis. Although the duration of immature development and adult longevity varied among generations, these fluctuations did not follow a clear pattern, indicating overall stability in developmental performance. Several reproductive traits, including APOP, TPOP, oviposition period, fecundity, and sex ratio, also differed among generations but without showing a consistent directional trend. Among life table parameters, including intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R₀), and gross reproductive rate (GRR) were slightly higher in early generations, decreased in G10, remained relatively stable up to G40, and then declined in G50. Offspring sex ratio was generally female-biased, with temporary male bias at the beginning or end of the oviposition period in some generations. Overall, cattail pollen can enhance growth and reproduction in E. scutalis during intermediate generations; however, lower fecundity and reduced population growth in later generations indicate that this diet is not sustainable over the long term (up to 50 generations).