Abstract Single-cut red clover (Trifolium pratense L.) is an important forage seed crop in Western Canada due to its winter hardiness and economical value. However, infestation of lesser clover leaf weevil (Hypera nigrirostris F.) can lead to drastic yield losses (over 50%). The aim of this research was to evaluate the effectiveness of insecticides deltamethrin (Decis) and cyantraniliprole (Exirel) in controlling H. nigrirostris in red clover in both field and laboratory conditions and their impacts on the pollinator community. Pest pressure data in red clover fields was tracked during the 2018 and 2019 growing season in six locations. Under the field conditions both deltamethrin and cyantraniliprole were effective at controlling H. nigrirostris numbers. However, only deltamethrin provided rapid pest suppression in 24 h after treatment application. Rearing H. nigrirostris larvae on treated plants in laboratory conditions showed similar results where both insecticides significantly reduced H. nigrirostris numbers in 10–12 days after treatment. The abundances of H. nigrirostris was always negatively related to seed yield regardless of treatment and initial weevil pressure. Seed yield was significantly lower in untreated controls whereas no differences were found between deltamethrin and cyantraniliprole. In contrast, no yield response was found when H. nigrirostris abundance was lower than 4 larvae per 10 shoots. Unexpectedly, densities of bees were not affected by either treatment and were not related to seed yield. Overall, results indicate that both insecticides can provide sufficient H. nigrirostris control, and that pollinator densities are not limiting seed yield, whereas lack of H. nigrirostris management can cause substantial yield losses.

中文翻译：

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评估化学控制方案及其对加拿大西部小型三叶草象鼻虫 (Hypera nigrirostris) 和红三叶草传粉者的影响

摘要 单切红三叶草(Trifolium pratense L.) 具有抗寒性和经济价值，是加拿大西部重要的牧草种子作物。然而，较小的三叶草象鼻虫 (Hypera nigrirostris F.) 的侵染会导致严重的产量损失（超过 50%）。本研究的目的是评估杀虫剂溴氰菊酯 (Decis) 和溴氰虫酰胺 (Exirel) 在田间和实验室条件下控制红三叶草中的黑化黑麦草的有效性及其对传粉媒介群落的影响。在 2018 年和 2019 年生长季节期间，在六个地点跟踪了红三叶草田的害虫压力数据。在田间条件下，溴氰菊酯和氰虫酰胺均能有效控制黑臭黑丝虫的数量。然而，只有溴氰菊酯在处理应用后 24 小时内提供了快速的害虫抑制。在实验室条件下在处理过的植物上饲养黑喉黑蛛幼虫显示出相似的结果，两种杀虫剂在处理后的 10-12 天内显着减少了黑蛛的数量。无论处理和初始象鼻虫压力如何，H. nigrirostris 的丰度始终与种子产量呈负相关。未处理对照的种子产量显着降低，而溴氰菊酯和氰虫酰胺之间没有发现差异。相反，当黑鱼丰度低于每 10 个枝条 4 个幼虫时，没有发现产量响应。出乎意料的是，蜜蜂的密度不受任何一种处理的影响，并且与种子产量无关。总体而言，结果表明这两种杀虫剂都可以提供足够的 H. nigrirostris 控制，并且授粉媒介的密度不会限制种子产量，而缺乏 H. nigrirostris。