Pea aphids, , are one of the major insect pests of faba bean (). Infestations of pea aphids on faba bean can occur at any plant growth stage and result in drastic yield losses (up to 100%). There was no established guideline to determine when to manage pea aphids on faba bean in Saskatchewan. We conducted a field study to develop an economic threshold for pea aphids on faba bean at six sites in the Saskatoon area in 2019 and 2020. No choice experiments were performed to determine pea aphid growth rate on tannin and low tannin faba bean. Under field conditions, the population of pea aphids on faba bean doubled in approximately 5.25 ± 0.19 days. The average economic threshold (ET) was 34–50 aphids per main stem of a plant. This ET provides a 7-day lead time before aphid populations are expected to exceed the economic injury level (EIL) of 680–984 cumulative aphid days or 96 to 142 aphids per faba bean main stem. All ETs were estimated based on the cost of registered insecticides and the average of three benchmark prices (high, medium and low) of faba bean from January 2018 to July 2021. Laboratory no-choice bioassays demonstrated no significant effect of faba bean tannins on pea aphid growth. Therefore, economic thresholds established in this study are applicable to both tannin and low tannin varieties of faba bean.

中文翻译：

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单宁和低单宁蚕豆中豌豆蚜的经济阈值和经济危害水平


豌豆蚜虫是蚕豆的主要害虫之一。豌豆蚜虫对蚕豆的侵染可能发生在任何植物生长阶段，并导致产量急剧下降（高达 100%）。没有既定指南来确定何时在萨斯喀彻温省管理蚕豆上的豌豆蚜虫。我们于 2019 年和 2020 年在萨斯卡通地区的六个地点进行了一项实地研究，以确定蚕豆上豌豆蚜的经济阈值。没有进行任何选择实验来确定单宁和低单宁蚕豆上豌豆蚜的生长率。在田间条件下，蚕豆上的豌豆蚜虫数量在大约 5.25 ± 0.19 天内翻了一番。平均经济阈值 (ET) 为每株植物主茎 34-50 只蚜虫。该 ET 提供了 7 天的提前时间，预计蚜虫种群将超过 680-984 个累积蚜虫日或每个蚕豆主茎 96 至 142 只蚜虫的经济损害水平 (EIL)。所有ETs都是根据注册杀虫剂的成本和2018年1月至2021年7月蚕豆三个基准价格（高、中、低）的平均值估算的。实验室无选择生物测定表明蚕豆单宁对豌豆没有显着影响蚜虫生长。因此，本研究建立的经济阈值适用于单宁和低单宁蚕豆品种。