Multiple resistance to glyphosate and imazethapyr in Bidens subalternans

ABSTRACT Glyphosate has been widely used to control greater beggarticks populations that are resistant to acetolactate synthase (ALS) inhibitors in South America. However, herbicide control failures has been observed over the last three growing seasons in grain production areas of Paraguay. In this research, we report the first case of multiple resistance to glyphosate (EPSPs) and imazethapyr (ALS) in greater beggarticks (Bidens subalternans) population from Paraguay. This conclusion was supported by dose-response experiments conducted in two consecutive years (2018 and 2019) with a putative resistant (R) and a susceptible (S) population. Alternative herbicides were also tested for post-emergence control of R population. For glyphosate, the resistant factor (RF) values were 8.8- (2018) and 15.7-fold (2019). For imazethapyr, the RF values were 59- and 58-fold, in 2018 and 2019, respectively. Treatments with 2,4-D, dicamba, 2,4-D + glyphosate, dicamba + glyphosate, lactofen, fomesafen, ammonium-glufosinate, atrazine, and bentazon provided more than 80% control of the R population. This is the first case of multiple resistance to glyphosate and imazethapyr in greater beggarticks (Bidens subalternans) in the world. The mechanisms underlying resistance in this biotype should be evaluated in future research.

【摘要】草甘膦（glyphosate）目前已被广泛用于防控南美洲地区对乙酰乳酸合酶（ALS）抑制剂产生抗性的大狼把草（greater beggarticks，Bidens subalternans）种群。然而，近三个生长季以来，巴拉圭粮食产区已观测到除草剂防控失效的情况。本研究首次报道了巴拉圭地区大狼把草（Bidens subalternans，greater beggarticks）种群对草甘膦（EPSPS靶标酶）和咪唑乙烟酸（imazethapyr，ALS抑制剂）产生多重抗性的案例。该结论得到了连续两年（2018年与2019年）开展的剂量反应试验的支持，试验所用材料为推定抗性（R）种群与敏感（S）种群。此外，本研究还测试了多种备选除草剂，用于该抗性种群的苗后防治。针对草甘膦，抗性系数（RF）值在2018年为8.8倍，2019年为15.7倍；针对咪唑乙烟酸，2018年与2019年的抗性系数值分别为59倍与58倍。施用2,4-滴、麦草畏、2,4-滴+草甘膦、麦草畏+草甘膦、乳氟禾草灵、氟磺胺草醚、草铵膦铵盐、莠去津以及苯达松的处理，对该抗性种群的防治效果均超过80%。本研究为全球范围内首次报道大狼把草（Bidens subalternans）对草甘膦与咪唑乙烟酸产生多重抗性的案例。该生物型的抗性机制有待在后续研究中进一步解析。