Genetic dissimilarity for resistance to Mononychellus tanajoa (bondar) (Acari, Tetranychidae) among domesticated and wild Manihot species

ABSTRACT The aim of this study was to evaluate the genetic dissimilarity among wild and domesticated species of Manihot for resistance to cassava green mite during the insect life cycle. Nine accessions of wild Manihot species, M. esculenta ssp. flabellifolia, M. esculenta ssp. peruviana, and M. carthaginensis ssp. glaziovii, and two clones of M. esculenta (Cigana Preta and Sacaí) were evaluated under laboratory conditions at 25 ± 1°C, 70 ± 10% RH, and a 12-h photophase. Daily observations during the mite life cycle stages (larva-adult) were recorded. The data were subjected to an analysis of variance, a Scott-Knott test (5%), and Singh criterion, cluster, and principal component analyses. The larval-adult period ranged from 5.53 to 7.01 days: the longest period was observed on an M. glaziovii accession (GLA-19-DF) and the shortest on an M. flabellifolia accession (FLA-025V). The UPGMA method allowed the division of the genotypes into six groups, with the greatest distance between the FLA-025V and GLA-19-DF accessions. The first two main components explained 77.50% of the total accumulated variation. The association of the longest cycle duration of M. tanajoa with the lowest larval-adult viability suggests that GLA-19-DF is less favorable to mite development compared to the other accessions. Significant variability among the genotypes was observed.

摘要 本研究旨在评估野生与栽培木薯属（Manihot）物种在昆虫生命周期中对木薯绿螨的抗性遗传差异。本试验选取9份野生木薯属种质，包括M. esculenta ssp. flabellifolia、M. esculenta ssp. peruviana以及M. carthaginensis ssp. glaziovii，以及2份栽培木薯（M. esculenta）无性系（Cigana Preta与Sacaí），在实验室条件（温度25±1℃、相对湿度70±10%、光周期12小时）下开展抗性评估。在螨类生命周期各阶段（幼虫至成虫期）进行每日观测记录。对试验数据进行方差分析、5%显著性水平下的Scott-Knott检验、Singh准则分析、聚类分析及主成分分析。幼虫至成虫的发育时长介于5.53至7.01天之间，其中最长发育时长见于M. glaziovii种质GLA-19-DF，最短发育时长见于M. flabellifolia种质FLA-025V。采用UPGMA法可将供试基因型划分为6个类群，FLA-025V与GLA-19-DF种质间的遗传距离最大。前两个主成分累计解释了总变异的77.50%。木薯绿螨（M. tanajoa）的最长发育周期与最低的幼虫-成虫存活率相关联，表明相较于其他种质，GLA-19-DF更不利于螨类的生长发育。供试基因型间存在显著遗传变异。