TY  - JOUR
JF  - Acarologia
T1  - Maternal effects mediate thermal response: Divergent performance between winter and summer egg-derived offspring in the spider mite Schizotetranychus brevisetosus
VL  - 66
IS  - Suppl
SP  - 95
EP  - 95
PY  - 2026
SN  - 0044-586X
SN  - 2107-7207
PB  - Les Amis d'Acarologia
AU  - Katsura, Ito
UR  - https://doi.org/10.24349/wqgb-nb1v
DO  - 10.24349/wqgb-nb1v
DA  - 2026-07-20
ET  - 2026-07-20
KW  - Postembryonic development
KW  - Transgenerational effects
KW  - Trade-offs
KW  - Evergreen hosts
KW  - Thermal response
AB  - Maternal effects play a crucial role in allowing offspring to adapt to fluctuating environments. In some spider- mite genera, mothers produce different types of eggs—diapause (winter) and non-diapause (summer) eggs—to survive unfavorable seasons, and this phenomenon is considered a kind of maternal effect. However, whether maternal effects extend beyond the embryonic period and influence postembryonic development across a wide range of temperatures remains unresolved. We investigated the developmental rates and survival of the spider mite Schizotetranychus brevisetosus Ehara, which inhabits evergreen oak leaves, from the egg stage to adult emergence under constant temperatures ranging from 15 °C to 35 °C. For each temperature treatment, 48 individuals from summer eggs and 36 individuals from winter eggs were examined. Our results revealed a striking trade-off in thermal responses between individuals derived from different egg types. At a low temperature (15 °C), individuals from winter eggs showed significantly higher survival rates and faster developmental rates compared to those from summer eggs. This enhanced performance at low temperatures is consistent with the natural hatching period of winter eggs in early March, when night temperatures frequently fall below 10 °C. In contrast, individuals from summer eggs exhibited superior performance at higher temperatures (particularly at 32.5 °C and 35 °C). While total survival to adulthood was significantly higher for summer-egg individuals at temperatures of 27.5 °C and above, survival curve analyses revealed that these differences were more pronounced at 32.5 °C and above. At moderate temperatures (17.5–25 °C), no significant differences were detected between the two groups, indicating a crossover of reaction norms. These findings suggest that maternal environments do not only trigger egg diapause—though it is weak in S. brevisetosus—but also modify the physiological traits of offspring to match forthcoming seasonal thermal conditions. Such maternal-mediated postembryonic trade-offs allow S. brevisetosus to optimize its life history in a temperate climate. This study provides empirical evidence that maternal effects are a key mechanism for seasonal adaptation in tetranychid mites and extend to the postembryonic stages. constant temperatures ranging from 15 °C to 35 °C.”: “For each temperature treatment, 48 individuals from summer eggs and 36 individuals from winter eggs were examined.
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