Molecular phylogeny and identification of agromyzid leafminers in China,with a focus on the worldwide genus Liriomyza(Diptera:Agromyzidae)

Leaf-mining flies(Diptera:Agromyzidae)are a diverse family of small-bodied insects that feed on living plant tissues as larvae.Various species in this family are considered globally invasive and have caused great agricultural economic losses.In China,economically important vegetable crops have been seriously damaged by these pest insects,especially by species of the genus Liriomyza.However,these species are difficult to differentiate because of their morphological similarities,and the Chinese fauna remains poorly known.To explore the relevant pest species in China and their phylogeny,agromyzid leafminers were collected from 2016 to 2019,and identified based on morphological characteristics and DNA barcodes.In total,27 species from five genera of Agromyzidae were sampled and identified,including 16species of Liriomyza.Both mitochondrial and nuclear genes were used to reconstruct their phylogenetic relationships and estimate the divergence time.Highly congruent and well-supported phylogenetic trees were obtained using the Bayesian inference and maximum-likelihood methods.This analysis revealed two main clades in Liriomyza,and clade 2was inferred to have diverged from clade 1 approximately 27.40 million years ago(95%highest posterior density:23.03–31.52 million years ago)in the Oligocene.Differences were observed in the distribution patterns and host associations between the Liriomyza clades.Clade 2 species are distributed in cool,high-latitude environments,suggesting that they may have evolved into a cool-adapted lineage.

Thelytokous Diglyphus wani:A more promising biological control agent against agromyzid leafminers than its arrhenotokous counterpart

Diglyphus wani(Hymenoptera:Eulophidae)is a dominant parasitoid that attacks agromyzid leafminers.Two reproductive types occur in D.wani:arrhenotoky(in which virgin females produce only male offspring;and virgin females mate with males to produce bisexual offspring)and thelytoky(in which virgin females produce female offspring).As a potential biological control agent,exploring the differences in the relevant biological parameters of both strains is necessary.In this study,comparisons between the two strains of D.wani were performed by evaluating the life table and host-killing rate.The thelytokous strain exhibited significantly better life table parameters than its arrhenotokous counterpart.Higher values for the intrinsic rate of increase,finite rate of increase,net reproductive rate,and fecundity were found in the thelytokous strain.The thelytokous strain also performed better than the arrhenotokous strain in terms of net parasitism,host-feeding,host-stinging,and total host-killing rates.Thus,populations of the thelytokous strain could grow fast and kill more hosts.In conclusion,the thelytokous strain of D.wani may be the more promising biological agent against agromyzid leafminers compared to its arrhenotokous counterpart.Also,since the thelytokous strain of D.wani is only known to produce females,it should be given priority in future biocontrol applications owing to the cost savings of breeding only females.

基于mtCOI基因序列的中国葱斑潜蝇不同地理种群遗传多样性分析

【目的】葱斑潜蝇Liriomyza chinensis是葱蒜类蔬菜上的重要经济害虫,在我国广泛分布。本研究旨在阐析中国葱斑潜蝇的地理种群遗传分化。【方法】以中国8省12个不同地理种群的253头葱斑潜蝇为样本,测定其mtCOI基因序列;依据获得的mtCOI基因序列,利用MEGA7.0,DnaSP 6.1和Arlequin 3.5等软件对葱斑潜蝇地理种群的遗传多样性、基因流水平和遗传变异等进行分析。【结果】在253头个体的759 bp mtCOI基因片段中,获得13个单倍型,各单倍型间K2P遗传距离均小于0.02;其中单倍型Hap1为12个地理种群所共享,总发生频率高达81.82%。总群体单倍型多样性较低(Hd=0.327),核苷酸多样性(Pi)为0.00159,核苷酸平均差异数(K)为1.21011;葱斑潜蝇总群体遗传分化程度中等(F ST=0.06971),基因交流较充分(Nm=3.33629)。分子方差分析(AMOVA)结果表明,遗传变异来源为群体内;总群体Tajima’s D检验值为显著负值;Mantel检测结果说明种群间的遗传距离与地理距离没有相关性。【结论】中国葱斑潜蝇地理种群的遗传多样性较低,基因交流较充分,遗传分化程度中等,且地理距离并不影响其遗传分化程度;葱斑潜蝇总群体在较近的历史时期未经历明显的种群扩张和种群增长。

补充非寄主源食物显著提高万氏潜蝇姬小蜂孤雌产雌品系对美洲斑潜蝇的控害潜力

【目的】万氏潜蝇姬小蜂Diglyphus wani是潜叶蝇类害虫的重要寄生蜂,可以孤雌产雌生殖,仅产生雌性后代,具有潜在的生防应用价值。该寄生蜂为寄主取食型寄生蜂,自然条件下不仅可取食非寄主源食物,也可直接取食寄主幼虫。本研究旨在探究补充非寄主源食物对其生防效果的影响,从而有效指导其大规模饲养和田间应用。【方法】以万氏潜蝇姬小蜂的孤雌产雌品系为对象,在室内持续恒温25℃条件下,以2龄末至3龄初美洲斑潜蝇Liriomyza sativae幼虫为寄主,比较提供3种营养源食物(仅提供寄主、寄主+20%葡萄糖水、寄主+20%蜂蜜水)时万氏潜蝇姬小蜂成虫的控害潜力的差异。【结果】与仅提供寄主的处理相比,补充非寄主食物20%葡萄糖水和20%蜂蜜水均能显著提高万氏潜蝇姬小蜂的成虫寿命(分别为2.4和2.1倍)、寄生致死寄主数(分别为3.2和2.9倍)、取食致死寄主数(分别为2.7和2.2倍)和总致死寄主数(分别为2.8和2.4倍);与仅提供寄主和补充非寄主食物20%蜂蜜水的相比,补充提供非寄主食物20%葡萄糖水能显著增强该蜂的叮蛰致死寄主数,但补充提供20%蜂蜜水与仅提供寄主处理的叮蛰致死寄主数之间差异不显著;补充提供20%葡萄糖水和20%蜂蜜水均显著增强万氏潜蝇姬小蜂的日均寄生致死寄主数和日均总致死寄主数,但不影响日均取食致死寄主数和日均叮蛰致死寄主数;且补充提供20%葡萄糖水和20%蜂蜜水两个处理间寄生蜂对美洲斑潜蝇的总致死寄主数无显著差异。3种食物源条件下,万氏潜蝇姬小蜂日均总致死寄主数在17头以上,而非繁殖型致死(寄生蜂叮蛰和取食)数占总致死寄主数比例最高。此外,在3种食物源条件下,寄生蜂的取食致死寄主数与寄生致死寄主数、成蜂寿命、总致死寄主数均显著正相关。【结论】万氏潜蝇姬小蜂可以通过寄主取食维持寿命、促进繁殖以及加强控害能力。补充非寄主源食物可以进一步延长该蜂的寿命并增强其控害能力。因此,其孤雌产雌品系有潜力成为防控美洲斑潜蝇的生防作用物,本研究结果可为万氏潜蝇姬小蜂孤雌产雌品系的室内饲养和田间释放应用提供依据和指导。

甘肃白银地区潜叶蝇及其寄生蜂的组成和发生调查

【目的】明确严重危害甘肃省白银地区作物的潜叶蝇及天敌寄生蜂的多样性和种群组成。【方法】采用五点取样法田间调查潜叶蝇危害的蔬菜、花卉、杂草并采样,室内对潜叶蝇及其寄生蜂进行形态鉴定和分子鉴定。【结果】在2016-2020年在甘肃白银地区采集的样本中发现6种常见潜叶蝇,包括本地种豌豆彩潜蝇Chromatomyia horticola和葱斑潜蝇Liriomyza chinensis,入侵种南美斑潜蝇L.huidobrensis、三叶草斑潜蝇L.trifolii、番茄斑潜蝇L.bryoniae和美洲斑潜蝇L.sativae。其中,豌豆彩潜蝇为优势种,可危害多科寄主植物;葱斑潜蝇仅在大葱上发现危害;南美斑潜蝇在温室内的蔬菜上发生严重;三叶草斑潜蝇首次在白银市发现;番茄斑潜蝇与美洲斑潜蝇的危害相对较轻。此外,调查的潜叶蝇寄生蜂包括3科12属24种,优势种包括豌豆潜蝇姬小蜂Diglyphus isaea、芙新姬小蜂Neochrysocharis formosa、万氏潜蝇姬小蜂D.wani和西伯利亚离颚茧蜂Dacnusa sibirica。【结论】一方面白银市应加强监测和预警入侵性潜叶蝇的发生,另一方面白银市潜叶蝇的天敌寄生蜂种类丰富,对田间主要危害的潜叶蝇可能发挥着重要的自然防控作用,建议保护利用本地寄生蜂天敌。

温度对芙新姬小蜂孤雌产雌品系成虫控制斑潜蝇的潜力的影响

【目的】芙新姬小蜂Neochrysocharis formosa是潜叶蝇类害虫的优势寄生蜂。该寄生蜂具有两性生殖和孤雌产雌生殖两种繁殖模式,其孤雌产雌品系可在低密度下快速建立种群,无需饲养雄蜂,具有种群繁育成本低,生防应用潜力突出等优点。本研究旨在明确环境温度对芙新姬小蜂孤雌产雌品系控害潜力的影响,为该蜂的低成本规模化繁育、田间释放等应用实践提供参考。【方法】在室内以美洲斑潜蝇Liriomyza sativae 2龄末至3龄初幼虫为寄主,统计4个温度(22,26,30和34℃)下芙新姬小蜂孤雌产雌品系雌成虫的取食致死寄主数、寄生致死寄主数、叮蛰致死寄主数、总致死寄主数、日均致死寄主数和成蜂寿命等生活史和控害参数。【结果】随温度升高,芙新姬小蜂孤雌产雌品系雌成虫对美洲斑潜蝇幼虫取食致死寄主数、寄生致死寄主数、叮蛰致死寄主数、总致死寄主数和日均总致死寄主数呈现先增加后降低的趋势,其中取食致死寄主数、寄生致死寄主数和叮蛰致死寄主数在30℃下最高,分别为236.1,69.2和49.7头;在34℃下最低,分别为115.2,19.8和21.6头。总致死寄主数在26℃(282.4头)和30℃(355.0头)下显著高于22℃(194.5头)和34℃下(156.5头);日均总致死寄主数在30℃下最高(25.5头)。此外,随着环境温度升高,芙新姬小蜂孤雌产雌品系雌成虫的寿命逐渐缩短,在22℃下最长(16.9 d),在34℃下最短(7.2 d)。【结论】尽管高温缩短了芙新姬小蜂孤雌产雌品系成虫的寿命,但其在30℃下控害能力较强,说明芙新姬小蜂孤雌产雌品系成虫可在30℃高温条件下对耐高温的斑潜蝇如美洲斑潜蝇发挥其控害潜力。