Sudo M, Osakabe M
Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan. Present Address: Natural Resources Inventory Center, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan.
Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
Environ Entomol. 2015 Dec;44(6):1605-13. doi: 10.1093/ee/nvv131. Epub 2015 Aug 13.
Seasonal population dynamics of an herbivorous mite has been documented in terms of the relationship between thermoresponses and temporal biological factors such as resource availability or predation risk. Although recent studies emphasize the deleterious effects of solar ultraviolet-B (UVB; 280-320 nm wavelengths) radiation on plant-dwelling mites, how UVB affects mite population remains largely unknown. On a wild shrub Viburnum erosum var. punctatum in Kyoto, an herbivorous false spider mite, Brevipalpus obovatus Donnadieu, occurs only in autumn. Females of this species lay one-third of their eggs on upper leaf surfaces. Oviposition on upper surfaces is beneficial for avoiding predation by phytoseiids, but exposes eggs to solar UVB and heat stress. To test the hypothesis that the seasonal occurrence of this mite is determined by interactions between solar UVB radiation and temperature, we examined variation in egg hatching success under near-ambient and UV-attenuated sunlight conditions from spring to autumn. The UV-attenuation significantly improved hatching success. However, most eggs died under heat stress regardless of UV treatments in July and August. We established a deterministic heat stress-cumulative UVB dose-egg hatching success response model, which we applied to meteorological data. The model analyses illustrated lower and higher survivability peaks in late May and October, respectively, which partly corresponded to data for annual field occurrence, indicating the importance of solar UVB radiation and heat stress as determinants of the seasonal occurrence of this mite.
草食性螨类的季节性种群动态已根据温度响应与资源可用性或捕食风险等时间生物学因素之间的关系进行了记录。尽管最近的研究强调了太阳紫外线B（UVB；波长280 - 320纳米）辐射对栖息在植物上的螨类的有害影响，但UVB如何影响螨类种群在很大程度上仍不清楚。在京都的一种野生灌木日本荚蒾变种（Viburnum erosum var. punctatum）上，一种草食性伪叶螨，卵形短须螨（Brevipalpus obovatus Donnadieu），仅在秋季出现。该物种的雌性将其三分之一的卵产在上部叶片表面。在上部表面产卵有利于避免被植绥螨捕食，但会使卵暴露于太阳UVB和热应激之下。为了检验这种螨的季节性出现是由太阳UVB辐射与温度之间的相互作用所决定的这一假设，我们研究了从春季到秋季在近自然和紫外线减弱的阳光条件下卵孵化成功率的变化。紫外线减弱显著提高了孵化成功率。然而，在7月和8月，无论紫外线处理如何，大多数卵在热应激下死亡。我们建立了一个确定性的热应激累积UVB剂量 - 卵孵化成功率响应模型，并将其应用于气象数据。模型分析表明，分别在5月下旬和10月出现较低和较高的生存峰值，这部分与年度田间出现的数据相对应，表明太阳UVB辐射和热应激作为这种螨季节性出现的决定因素的重要性。
