Contrasting effects of Wolbachia on cytoplasmic incompatibility and fecundity in the haplodiploid mite Tetranychus urticae

Recent studies on Wolbachia‐induced incompatibility in haplodiploid insects and mites have revealed a diversity of cytoplasmic incompatibility (CI) patterns among host species. Here, we report intraspecific diversity in CI expression among four strains of the arrhenotokous mite Tetranychus urticae and in T. turkestani. Variability of CI expression within T. urticae ranged from no CI to complete CI, and included either female embryonic mortality or male conversion types of CI. A fecundity cost attributed to the infection with the high‐CI Wolbachia strain was the highest ever recorded for Wolbachia (?80 to ?100% decrease). Sequence polymorphism at a 550‐bp‐portion of Wolbachia wsp gene revealed two clusters distant by 21%, one of which included three Wolbachia strains infecting mite populations sampled from the same host‐plant species, but showing distinct CI patterns. These data are discussed in the light of theoretical predictions on the evolutionary pathways followed in this symbiotic interaction.     

The distribution and evolutionary history of Wolbachia infection in native and introduced populations of the invasive argentine ant (Linepithema humile)

Wolbachia pipientis is a maternally transmitted bacterium that often alters the life history of its insect host to maximize transmission to subsequent generations. Here we report on the frequency and distribution of Wolbachia infection in a widespread invasive species, the Argentine ant (Linepithema humile). We screened 1175 individual Argentine ants from 89 nests on five continents and several islands, including numerous locations in both the native (South American) and introduced ranges. We detected Wolbachia in four of 11 native populations, but only one of 21 introduced populations was infected. In the Argentine ant's native range, the distribution of Wolbachia supergroups A and B was nonoverlapping. By coupling infection frequency data with behaviourally defined colony boundaries, we show that infected and uninfected colonies are often adjacent to one another, supporting the proposition that little female-mediated gene flow occurs among Argentine ant colonies. We also conduct a phylogenetic analysis, and show that the Wolbachia infecting both native and introduced populations of Argentine ants belong to two lineages that appear to be specialized on infecting New World ants. One other lineage of Wolbachia has undergone frequent, recent episodes of horizontal transmission between distantly related, introduced insect hosts.     

First record of the bacterial endosymbiont Wolbachia for phytophagous hoverflies from genus Merodon (Diptera: Syrphidae)

Wolbachia is a widespread bacterial endosymbiont among arthropod species. It influences the reproduction of the host species and also mitochondrial DNA diversity. Until now there were only a few studies that detected Wolbachia infections in hoverflies (Diptera: Syrphidae), and this is the first broader study with the aim of examining the incidence of Wolbachia in the hoverfly genus Merodon. The obtained results indicate an infection rate of 96% and the presence of both Wolbachia supergroup A and B, which are characteristic for most of the infected arthropod species. Additionally, the presence of multiple Wolbachia strains in the Merodon aureus group species was detected and the mitochondrial DNA COI‐based relationships of the group are discussed in the light of infection. Finally, we discuss plant‐mediated horizontal transmission of Wolbachia strains among the studied hoverfly species.     

沟眶象体内感染的Wolbachia的wsp基因克隆与序列分析

Wolbachia是广泛分布于昆虫细胞内的一类共生菌,为明确Wolbachia在沟眶象Eucryptorrhynchus chinensis(Olivier)体内的感染情况和分类地位,采用Wolbachia的wsp基因片段对沟眶象5个地理种群(宁夏灵武、中宁、中卫、安徽淮北、山东聊城)共100个样本,进行分子检测。经过克隆和测序得到wsp基因片段593 bp(Gen Bank number:KP713759),明确了沟眶象体内存在Wolbachia的感染,并且其在不同地理种群内的感染率均为100%;通过wsp通用引物检测发现沟眶象体内感染了1种Wolbachia,属于A群Dro亚群。     

Wolbachia在螟黄赤眼蜂种群内的分布及其遗传稳定性

本文通过对Wolbachia的wsp及16S rDNA基因的PCR扩增及克隆测序,明确了Wolbachia在华南、华北不同作物田间螟黄赤眼蜂Trichogramma chilonis种群内的分布情况.结果表明,在所有检测的螟黄赤眼蜂个体内都存在着Kue和Pip两组Wolbachia,双重感染率达到了100%.在不同温度下用米蛾Corcyra cephalonica Stainton卵饲养多代后,螟黄赤眼蜂体内的Wolbachia类型及感染率未发生改变,表明Wolbachia能够在螟黄赤眼蜂体内稳定遗传,不受环境温度的直接影响.本研究中螟黄赤眼蜂为两性生殖或孤雌产雄生殖,Wolbachia未能引起赤眼蜂的产雌孤雌生殖.首次报道了Wolbachia在我国螟黄赤眼蜂野生种群内的分布情况及其遗传稳定性.     

我国烟粉虱自然种群中存在广泛的Wolbachia感染现象

Wolbachia是广泛分布于节肢动物生殖组织中的细胞质遗传的一类共生菌,可以引起宿主生殖行为的改变.烟粉虱是重要的农业害虫,已有的研究表明烟粉虱中存在Wolbachia的感染,但所检测到的感染率不高,并且迄今在烟粉虱中所检出的Wolbachia均属于B组群.该研究从我国河北、新疆、北京、山东、浙江、广西、海南、广州和福建采集到18个烟粉虱地理种群,首先基于ITS1 rDNA克隆测序鉴定了烟粉虱的生物型,然后采用自行设计的Wolbachia 16S rDNA及wsp基因的专用引物对所采集到的烟粉虱种群进行了分子检测.结果表明几乎所有的烟粉虱自然种群中都存在Wolbachia感染,同时还发现B/Q生物型烟粉虱中主要感染A组群Wolbachia,而非B/Q生物型烟粉虱中存在大量的超感染现象.该研究显示烟粉虱自然种群中Wolbachia的感染率比预想的要高得多,而分子检测方法的灵敏度可能是影响Wolbachia感染率研究的关键因素之一.     

茶尺蠖和灰茶尺蠖内共生菌Wolbachia的分子检测及序列分析

【目的】对茶尺蠖Ectropis obliqua及其近缘种灰茶尺蠖E.grisescens体内共生菌Wolbachia进行分子鉴定,确定两者体内Wolbachia的感染率及其进化地位,为进一步探讨其对茶尺蠖和灰茶尺蠖的潜在影响提供科学依据。【方法】采用Wolbachia的16S r RNA、fts Z和wsp基因特异性引物,通过PCR扩增法检测了我国3个茶尺蠖地理种群(浙江杭州、余杭和江苏无锡)和3个灰茶尺蠖地理种群(浙江新昌、湖北浠水和江西南昌)中Wolbachia的感染情况,并进行测序和序列分析。【结果】茶尺蠖和灰茶尺蠖都感染了Wolbachia,灰茶尺蠖的Wolbachia感染率为100%,但茶尺蠖的Wolbachia感染率在22%~95%,且PCR产物电泳得到的条带微弱。wsp序列在茶尺蠖和灰茶尺蠖种间、种内无差异;但16S r RNA序列在茶尺蠖和灰茶尺蠖种间、种内差异为0.362%~0.727%之间;茶尺蠖样本未成功扩增出fts Z序列,灰茶尺蠖样本获得2条fts Z基因序列差异为1.647%。基于Wolbachia的16S r RNA和wsp基因构建的系统发育树表明,本研究中茶尺蠖和灰茶尺蠖种群所感染的Wolbachia全部属于B组的Pip亚组。【结论】茶尺蠖和灰茶尺蠖均被B组Pip亚组的Wolbachia感染,但感染率相差很大,这为研究Wolbachia对茶尺蠖和灰茶尺蠖生物学及生态学的影响奠定了基础。     

铃木氏果蝇不同地理种群中Wolbachia的检测和系统发育分析

铃木氏果蝇Drosophila suzukii是原产于东南亚地区的重要果树害虫, 近年来传入北美和欧洲等地区造成严重的危害。本研究利用Wolbachia的16S rDNA和wsp基因特异引物（分别为16S-F/16S-R和81F/691R）对铃木氏果蝇7个地理种群（中国的5个种群、 韩国的1个种群和美国的1个种群）的Wolbachia进行了PCR检测并对检测结果进行了比较; 对感染个体体内Wolbachia的16S rDNA基因片段进行测序, 确定了我国铃木氏果蝇体内Wolbachia的分类地位。基于Wolbachia的16S rDNA基因特异引物检测结果发现, 我国5个铃木氏果蝇种群广泛感染Wolbachia（感染率36.7%~80.0%）, 而韩国和美国2个种群均未检测到该菌的感染。而利用wsp基因特异引物无法检测到该菌。基于Wolbachia的16S rDNA基因构建系统发育树表明, 我国铃木氏果蝇种群感染的Wolbachia全部属于A组。这些结果为研究Wolbachia感染对铃木氏果蝇生物学及生态学的影响奠定了基础。     

沃尔巴克氏体在中国三种稻飞虱中的感染

用PCR方法检测了采集于不同地域稻田的3种稻飞虱共生菌沃尔巴克氏体(Wolbachia)的感染,发现灰飞虱Laodelphax striatellus、褐飞虱Nilaparvata lugens、白背飞虱Sogatella furcifera为沃尔巴克氏体所感染。克隆了编码沃尔巴克氏体外膜蛋白质的wsp基因并进行了序列测定。对wsp的RFLP分析证实了这些飞虱为单一沃尔巴克氏体感染。研究了灰飞虱中沃尔巴克氏体所诱导的胞质不相容性及其在不同地域灰飞虱中的分布。还发现能寄生于上述3种飞虱的稻虱红螯蜂也受同种沃尔巴克氏体感染。沃尔巴克氏体可能通过这种寄生蜂在不同昆虫间横向传播。     

High prevalence of Wolbachia infection does not explain unidirectional cytoplasmic incompatibility of Altica flea beetles

1. Wolbachia are intracellular bacteria found in a wide range of arthropods that can impact reproductive isolation of their hosts. Previous studies showed unidirectional cytoplasmic incompatibility (CI) and high infection rates by Wolbachia in the closely related leaf beetles Altica fragariae and Altica viridicyanea; however, whether this reproductive isolation was induced by Wolbachia remains unclear. 2. This study estimated the prevalence of Wolbachia in Altica beetles, assessed genetic diversity of Wolbachia strains infecting these beetles, and tested whether Wolbachia-induced CI explains reproductive isolation of A. fragariae and A. viridicyanea. 3. The results show that all of the 11 tested Altica species were infected by Wolbachia, and the infection rate was as high as 97.0% (n = 235). Multi-strain infections were common, being found in 10 of the 11 species tested and accounting for 23.0% of all screened specimens. In total, 35 Wolbachia strains were identified based on 208 wsp sequences obtained. Although a majority of A. fragariae and A. viridicyanea individuals from the Beijing population were infected with only one strain each, multi-strain infections did occur in both species. Antibiotic curing experiments did not change hatching success in either inter- or intraspecific crosses of A. fragariae and A. viridicyanea, indicating that these Wolbachia strains do not induce CI. These results were further corroborated by the lack of the Wolbachia cifB gene, which is responsible for causing CI. 4. These findings suggest that high prevalence of Wolbachia infection is unlikely to contribute to reproductive isolation and speciation in this system.