Frankliniella occidentalis (Pergande) and Thrips flavus (Schrank) (Thysanoptera: Thripidae) cause considerable damage to agricultural crops. In this study, we investigated the variations in the population density of these 2 thrips species in 2 sites (Dabai and Heilongtan) with different insecticide application levels. Bioassays were performed to determine the susceptibility of both thrips species to imidacloprid, abamectin, and high-bromine cyhalothrin in summer. The results showed that the F. occidentalis species were more abundant in Dabai than in Heilongtan during both winter and summer. The proportions of F. occidentalis in winter and summer were 28.32–43.35% and 61.79–76.02%, respectively. Moreover, F. occidentalis resistance against the 3 insecticides was significantly higher than that of T. flavus in both 2017 and 2019. Compared with 2017, the LC50 values of F. occidentalis populations in Dabai to imidacloprid, abamectin, and lambda-cyhalothrin increased to 100.076, 16.52, and 130.44 mg/liter, respectively. The number of F. occidentalis, reaching the proportion of 91.63% in 90 days, was significantly higher than that of the control after imidacloprid treatment. In conclusion, thrips interspecies competition is affected by the irrational use of insecticides, which may cause the replacement of native species by invasive species, thereby leading to an outbreak.

中文翻译：

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杀虫剂介导的蓟马物种、西花蓟马 (Pergande) 和黄蓟马 (Schrank) 的种群变化和毒性（缨翅目：蓟马科）

Frankliniella occidentalis (Pergande) 和 Thrips flavus (Schrank)（缨翅目：蓟马科）对农作物造成相当大的损害。在本研究中，我们调查了2个地点（大白和黑龙滩）不同杀虫剂施用水平下这2种蓟马种群密度的变化。进行生物测定以确定夏季两种蓟马对吡虫啉、阿维菌素和高溴氯氟氰菊酯的敏感性。结果表明，冬季和夏季，大白地区西花蓟马的数量均高于黑龙潭地区。冬季和夏季F. occidentalis的比例分别为28.32%~43.35%和61.79%~76.02%。此外，2017年和2019年西花蝽对3种杀虫剂的抗药性均显着高于黄蝽。与2017年相比，大白地区西花蝽种群对吡虫啉、阿维菌素、高效氯氟氰菊酯的LC50值增加至分别为 100.076、16.52 和 130.44 毫克/升。吡虫啉处理后，西花螟的数量在90 d内达到91.63%的比例，显着高于对照。总之，不合理使用杀虫剂会影响蓟马的种间竞争，可能导致本地物种被入侵物种取代，从而导致爆发。