Abstract Host plant traits strongly affect survivorship of insect herbivores, and host suitability is especially important for the wheat stem sawfly, Cephus cinctus Norton, which spends its entire egg, larval, and pupal periods in a single stem. Measuring larval survival inside stems from egg hatch through diapause-mediated dormancy is a potential measure of population size for the next year but is also useful in assessing effects of growing season precipitation and temperature. Larval growth is synchronized with host plant growth, and the larva cannot switch hosts. Thus, incorporating plant physiological time, as growing degree days (GDD), may yield a better prediction of larval survival. Therefore, we assessed wheat stem sawfly survival from early larval growth to the beginning of autumnal diapause in barley cultivars selected from across feed, forage, and two- or six-row malt groups. Field experiments were conducted in Gallatin and Chouteau counties, Montana, in 2016 and 2017. We used Kaplan-Meier estimation to assess larval survival among cultivars. We found that the survival of pre-diapause larvae was greatest in ‘Hockett' (36.5%) and lowest in ‘Celebration’ (15.4%). Precipitation and temperature during the growing season affected temporal patterns for larval survival across study sites. Adjusting survivorship curves using site-specific GDD accumulation allowed cultivar-specific survivorship to be estimated more precisely for each site, despite differing environmental influences. Our findings suggest that measuring wheat stem sawfly survival across barley cultivars and standardizing by site-specific GDDs may provide better recommendations on barley cultivars that impede wheat stem sawfly population growth and reduce economic losses.

中文翻译：

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降水和温度对大麦品种Cephus cinctus（膜翅目：Cephidae）幼虫存活的影响

摘要 寄主植物性状强烈影响昆虫食草动物的生存，寄主适宜性对小麦茎叶蜂 Cephus cinctus Norton 尤为重要，它的整个卵期、幼虫期和蛹期都在一个茎中。通过滞育介导的休眠来测量来自卵孵化的幼虫存活率是明年种群规模的潜在衡量标准，但也可用于评估生长季节降水和温度的影响。幼虫生长与寄主植物生长同步，幼虫不能转换寄主。因此，将植物生理时间作为生长期 (GDD) 考虑在内，可以更好地预测幼虫的存活率。因此，我们评估了从早期幼虫生长到秋季滞育开始的小麦茎叶蜂在从不同饲料中选择的大麦品种中的存活率，草料和两行或六行麦芽组。2016 年和 2017 年在蒙大拿州加拉廷县和乔托县进行了田间试验。我们使用 Kaplan-Meier 估计来评估品种之间的幼虫存活率。我们发现滞育前幼虫的存活率在 'Hockett' (36.5%) 中最高，在 'Celebration' 中最低 (15.4%)。生长季节的降水和温度影响了整个研究地点幼虫存活的时间模式。尽管环境影响不同，但使用特定地点的 GDD 积累调整生存曲线可以更准确地估计每个地点的特定品种生存率。