Department of Entomology, Kansas State University, Manhattan, Kansas, United States of America.
Department of Plant Protection, College of Agriculture, University of Baghdad, Baghdad, Iraq.
PLoS One. 2020 May 29;15(5):e0233507. doi: 10.1371/journal.pone.0233507. eCollection 2020.
The wheat curl mite, Aceria tosichella Keifer, one of the most destructive arthropod pests of bread wheat worldwide, inflicts significant annual reductions in grain yields. Moreover, A. tosichella is the only vector for several economically important wheat viruses in the Americas, Australia and Europe. To date, mite-resistant wheat genotypes have proven to be one of the most effective methods of controlling the A. tosichella-virus complex. Thus, it is important to elucidate A. tosichella population genetic structure, in order to better predict improved mite and virus management. Two genetically distinct A. tosichella lineages occur as pests of wheat in Australia, Europe, North America, South America and the Middle East. These lineages are known as type 1 and type 2 in Australia and North America and in Europe and South America as MT-8 and MT-1, respectively. Type 1 and type 2 mites in Australia and North America are delineated by internal transcribed spacer 1 region (ITS1) and cytochrome oxidase I region (COI) sequence differences. In North America, two A. tosichella genotypes known as biotypes are recognized by their response to the Cmc3 mite resistance gene in wheat. Aceria tosichella biotype 1 is susceptible to Cmc3 and biotype 2 is virulent to Cmc3. In this study, ITS1 and COI sequence differences in 25 different populations of A. tosichella of known biotype 1 or biotype 2 composition were characterized for ITS1 and COI sequence differences and used to model spatio-temporal dynamics based on biotype prevalence. Results showed that the proportion of biotype 1 and 2 varies both spatially and temporally. Greater ranges of cropland and grassland within 5000m of the sample site, as well as higher mean monthly precipitation during the month prior to sampling appear to reduce the probability of occurrence of biotype 1 and increase the probability of occurrence of biotype 2. The results suggest that spatio-temporal modeling can effectively improve A. tosichella management. Continual integration of additional current and future precipitation and ground cover data into the existing model will further improve the accuracy of predicting the occurrence of A. tosichella in annual wheat crops, allowing producers to make informed decisions about the selection of varieties with different A. tosichella resistance genes.
麦岩螨，Aceria tosichella Keifer，是全世界对面包小麦危害最大的节肢动物害虫之一，它每年都会导致小麦产量显著下降。此外，A. tosichella 还是美洲、澳大利亚和欧洲几种经济上重要的小麦病毒的唯一载体。迄今为止，抗螨小麦基因型已被证明是控制 A. tosichella-病毒复合体的最有效方法之一。因此，阐明 A. tosichella 种群遗传结构对于更好地预测和管理螨虫和病毒至关重要。在澳大利亚、欧洲、北美、南美和中东，有两种在小麦上发生的遗传上不同的 A. tosichella 种群。这些种群在澳大利亚和北美被称为 1 型和 2 型，在欧洲和南美则分别称为 MT-8 和 MT-1。澳大利亚和北美的 1 型和 2 型螨虫通过内部转录间隔区 1 区（ITS1）和细胞色素氧化酶 I 区（COI）序列差异来区分。在北美，两种已知为生物型的 A. tosichella 基因型因其对小麦 Cmc3 抗螨基因的反应而被识别。Aceria tosichella 生物型 1 对 Cmc3 敏感，生物型 2 对 Cmc3 有毒。在这项研究中，对 25 个不同种群的 A. tosichella 的 ITS1 和 COI 序列差异进行了特征分析，这些种群的生物型 1 或生物型 2 组成已知，并基于生物型流行率来模拟时空动态。结果表明，生物型 1 和 2 的比例在空间和时间上都有变化。在样本点 5000 米范围内的农田和草原面积越大，以及采样前一个月的平均月降水量越高，生物型 1 的发生概率越低，生物型 2 的发生概率越高。结果表明，时空建模可以有效地改善 A. tosichella 的管理。不断将当前和未来的降水和地面覆盖数据纳入现有模型中，将进一步提高预测年度小麦作物中 A. tosichella 发生的准确性，使生产者能够根据不同 A. tosichella 抗性基因的品种做出明智的选择。
