Data from: Combinations of plant water-stress and neonicotinoids can lead to secondary outbreaks of Banks grass mite (Oligonychus pratensis Banks)

Spider mites, a cosmopolitan pest of agricultural and landscape plants, thrive under hot and dry conditions, which could become more frequent and extreme due to climate change. Recent work has shown that neonicotinoids, a widely used class of systemic insecticides that have come under scrutiny for non-target effects, can elevate spider mite populations. Both water-stress and neonicotinoids independently alter plant resistance against herbivores. Yet, the interaction between these two factors on spider mites is unclear, particularly for Banks grass mite (Oligonychus pratensis; BGM). We conducted a field study to examine the effects of water-stress (optimal irrigation = 100% estimated evapotranspiration (ET) replacement, water stress = 25% of the water provided to optimally irrigated plants) and neonicotinoid seed treatments (control, clothianidin, thiamethoxam) on resident mite populations in corn (Zea mays, hybrid KSC7112). Our field study was followed by a manipulative field cage study and a parallel greenhouse study, where we tested the effects of water-stress and neonicotinoids on BGM and plant responses. We found that water-stress and clothianidin consistently increased BGM densities, while thiamethoxam-treated plants only had this effect when plants were mature. Water-stress and BGM herbivory had a greater effect on plant defenses than neonicotinoids alone, and the combination of BGM herbivory with the two abiotic factors increased the concentration of total soluble proteins. These results suggest that spider mite outbreaks by combinations of changes in plant defenses and protein concentration are triggered by water-stress and neonicotinoids, but the severity of the infestations varies depending on the insecticide active ingredient.叶螨(Spider mites)是一类侵染农业与园林植物的世界性害虫，其适宜生存环境为高温干旱条件，而气候变化正使得这类环境愈发频发且极端。现有研究表明，新烟碱类杀虫剂(neonicotinoids)——一类被广泛使用的内吸性杀虫剂，因其非靶标效应饱受争议——可提升叶螨种群数量。干旱胁迫与新烟碱类杀虫剂均可独立改变植物对植食性昆虫的抗性，然而二者对叶螨的复合调控效应尚不明确，针对班氏禾螨(Banks grass mite, Oligonychus pratensis; BGM)的相关研究尤为匮乏。本研究首先开展田间试验，探究干旱胁迫[最优灌溉为100%估算蒸散量(evapotranspiration, ET)补水，干旱胁迫组供水量为最优灌溉组的25%]与新烟碱类种子包衣处理[对照组、噻虫胺(clothianidin)、噻虫嗪(thiamethoxam)]对玉米(Zea mays，品种KSC7112)上定殖叶螨种群的影响。随后本研究设置可控田间笼养试验与平行温室试验，进一步验证干旱胁迫与新烟碱类杀虫剂对班氏禾螨及植物生理响应的调控效应。试验结果表明：干旱胁迫与噻虫胺处理可持续提升班氏禾螨种群密度，而噻虫嗪处理仅在玉米植株成熟阶段产生该效应；相较于单一施用新烟碱类杀虫剂，干旱胁迫与班氏禾螨取食对植物防御系统的调控效应更为显著；且班氏禾螨取食结合这两种非生物胁迫可提升植物总可溶性蛋白含量。本研究结果显示，干旱胁迫与新烟碱类杀虫剂可通过改变植物防御系统与可溶性蛋白浓度，共同诱发叶螨种群爆发，但虫害严重程度取决于杀虫剂有效成分的种类。