Yun-Li Tao

Genetic differentiation of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype Q based on mitochondrial DNA markers

In the present study, genetic differentiation of Bemisia tabaci (Gennadius) biotype Q was analyzed based on mitochondrial cytochrome oxidase I (mt COI) gene sequence. The results showed that B. tabaci biotype Q could be separated into two subclades, which were labeled as subclades Q1 and Q2. Subclade Q1 was probably indigenous to the regions around the Mediterranean area and subclade Q2 to Israel or Cyprus. It was because B. tabaci was composed of several genetically distinct groups with a strong geographical association between more closely related biotypes. Not all of the B. tabaci biotype Q in the non‐Mediterranean countries come from the same regions. Until now, all B. tabaci biotype Q in China were grouped into subclade Q1. The B. tabaci biotype Q introduced into the US included both subclades Q1 and Q2. The genetic structure analysis showed higher genetic variation of subclade Q1 than that of subclade Q2.

Evidence For Rapid Spatiotemporal Changes in Genetic Structure of an Alien Whitefly During Initial Invasion

The sweetpotato whitefly Bemisia tabaci Q species is a recent invader and important pest of agricultural crops in China. This research tested the hypothesis that the Q populations that establish in agricultural fields in northern China each year are derived from multiple secondary introductions and/or local populations that overwinter in greenhouses (the pest cannot survive winters in the field in northern China). Here, we report the evidence that the Q populations in agricultural fields mainly derive from multiple secondary introductions. In addition, the common use of greenhouses during the winter in certain locations in northern China helps increase the genetic diversity and the genetic structure of the pest. The genetic structure information generated from this long-term and large-scale field analysis increases our understanding of B. tabaci Q as an invasive pest and has important implications for B. tabaci Q management.

Carposina sasakii (Lepidoptera: Carposinidae) in its Native Range Consists of Two Sympatric Cryptic Lineages as Revealed by Mitochondrial COI Gene Sequences

The genetic differentiation and genetic structure of the peach fruit moth, Carposina sasakii Matsumura (Lepidoptera: Carposinidae), was investigated in China, where the moth is native. The mitochondrial cytochrome c oxidase I (COI) gene of 180 individuals from 16 collections were sequenced and analyzed. The results showed that two sympatric and cryptic mtDNA lineages existed within C. sasakii in China. The genetic differentiation has significant correlation with the geographical distance, but has no evidence for host plant associations. Our results of haplotype distribution suggest that the C. sasakii individuals can naturally move between areas, while the movement of individuals between long-distance locations may be associated with human activities such as the transport of fruit. Finally, an mitochondrial COI gene PCR-RFLP method was developed to differentiate the two cryptic mtDNA lineages within C. sasakii, which provides rapid and reliable tool for the future research of the two lineages.

Two Putative Bridgehead Populations of Aphelinus mali (Hymenoptera: Aphelinidae) Introduced in China as Revealed by Mitochondrial DNA Marker

Abstract In China, Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) was independently introduced as an endoparasitoid of the woolly apple aphid, Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae) from Japan in 1942 and from the former Soviet Union during 1953–1955. However, we do not know which introduction of this endoparasitoid plays important role in the control of E. lanigerum in China. To determine the status of this biological control agent in China, we collected 16 populations from 6 provinces (Shandong, Liaoning, Hebei, Shanxi, Xinjiang and Yunnan) and analyzed the 948 mtCOI gene from specimens in these samples. The results revealed that the A. mali in China consisted of 2 cryptic mitochondrial clades including 3 haplotypes, which indicated at least 2 independent introductions of the parasitoid into China. Our results showed that each of the populations that had been introduced into Shandong and Liaoning, respectively, had also established in many regions of China , where they play an important role in the control of E. lanigerum. Therefore it is very likely that both original introductions have served as bridgeheads to establish other populations in China. Genetic analyses together with field surveys should be helpful in the management of the woolly apple aphid.

Characterization and comparative profiling of miRNAs in invasive Bemisia tabaci (Gennadius) B and Q.

Background MicroRNAs (miRNAs) are small, conserved, non-coding RNAs that post-transcriptionally regulate gene expression. Bemisia tabaci (Gennadius) B and Q are two invasive and dominant whiteflies, and B. tabaci Q has been displacing B in China. Differences in biological traits (fecundity, host range, resistance to insecticides, etc.) as affected by miRNAs might be involved in the displacement. In this study, we performed high-throughput sequencing to identify miRNAs in B. tabaci B and Q. Results We identified 170 conserved miRNAs and 15 novel candidates, and found significant differences in the expression of miRNAs between B. tabaci B and Q. Conclusion Expression levels of miRNAs differ in B. tabaci B vs. Q. Additional research is needed to determine whether these differences are related to differences in the biology of B. tabaci B and Q, and whether these differences help explain why B. tabaci Q is displacing B in China.

Analysis of Genetic Diversity and Structure of Two Clades of Aphelinus mali (Hymenoptera: Aphelinidae) in China

Abstract Our prior research revealed that there are 2 mitochondrial clades of Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) in China, which are known as SD clade and LN clade. To further reveal their genetic characteristics and to determine the degrees of hybridization and gene flow between the 2 clades of A. mali in China, we analyzed the genetic diversities and genetic structures of 16 populations from 6 provinces (Shandong, Liaoning, Hebei, Shanxi, Xinjiang, and Yunnan) using 8 micro satellite loci. Our results showed that among the pure populations in the SD and LN clades, the greatest genetic diversities were found in the Qingdao, Shandong (QD) population and in the Dalian, Liaoning (DL) population. QD was the first population of the SD clade to be established, and DL was the first population of the LN clade to be established. In addition, genetic diversity was not substantially lower - and in some cases it was greater - in mixed-clade populations than in QD and DL. Individuals within each mitochondrial clade could not be differentiated based on microsatellite loci. Our data confirmed that the QD and DL populations, which were the first to be established in China, have served as bridgeheads for the other SD and LN populations in China. The results demonstrated that the hybridization or gene flow has occurred between the 2 mitochondrial clades.

Genetic Differentiation of Different Geographical Populations of Bemisia tabaci (Gennadius) Complex

Abstract Bemisia tabaci (Gennadius) is a species complex, which includes different geographical populations with genetic differentiation. The recent progress on the genetic differentiation of various geographical populations of B. tabaci complex was introduced. The genetic differentiation was further analyzed on the basis of the sequences of mtDNA COI and rDNA ITS1 recorded in the worlds GenBank. Five groups are defined on the basis of mtDNA COI and rDNA ITS1, including the Asia group, America group, Africa group, Australia group, and Biotype B/Mediterranean/Middle East/Northern Africa/Biotype Ms group. There are several ungrouped geographical classifications, such as the Uganda population, Ivory Coast population, and Taiwan population. Geographical isolation may be the most important factor that contributed to the genetic differentiation of various geographical populations of B. tabaci. Many populations with biological advantages invaded new regions and caused severe economic losses within human activity. It is necessary to strengthen the research of B. tabaci biotype to prevent the spread of invaded populations and the invasion of potentially dangerous populations.

Rapid Spread of a Recently Introduced Virus (Tomato Yellow Leaf Curl Virus) and Its Vector Bemisia tabaci (Hemiptera: Aleyrodidae) in Liaoning Province, China

ABSTRACT In Liaoning Province, China, tomato yellow leaf curl virus (TYLCV) was first detected in 2009 and in only four counties. To quantify the spread of TYLCV and to identify potential factors influencing its spread in Liaoning Province, we assayed for TYLCV within 1,055 whiteflies (Bemisia tabaci (Gennadius) complex) from 74 populations and 29 counties in 2011. The B. tabaci species of these individuals was determined based on molecular markers. TYLCV was found in 13 counties (Donggang, Liaoyang, Kazuo, Lingyuan, Heishan, Liaozhong, Kaiyuan, Taian, Dawa, Dashiqiao, Beizhen, Linghai, and Xingcheng) and was most frequently detected in the central plain. In addition, the percentage of whiteflies with TYLCV was significantly higher in B. tabaci Q than in B. tabaci B but was unrelated to the hosts (pepper, eggplant, tomato, cucumber, and kidney bean) on which the whiteflies had been collected. These results demonstrate that TYLCV has spread rapidly in Liaoning Province since its first detection and suggest that its spread is more closely associated with the introduction of B. tabaci Q than with the species of host plant. These findings also indicate that controls are now needed to reduce the further spread of TYLCV and that these controls should include the management of B. tabaci Q populations.

Invasion Genetics of Woolly Apple Aphid (Hemiptera: Aphididae) in China

ABSTRACT In China, the woolly apple aphid, Eriosoma lanigerum (Hausmann), was first detected as an invasive species during the 1910s to 1930s, restricted to Shandong, Liaoning, and Yunnan Provinces. However, since the 1990s, the pest has spread into many other areas of China. To determine the possible spread routes of the recently established populations, the genetic diversity and genetic structure of 24 populations in 10 provinces were analyzed using eight microsatellite loci. Analyses using STRUCTURE software identified two genetic clusters overall. Three populations from Yunnan and Xinjiang consisted of individuals originating from a single cluster. Nineteen populations from eight northern provinces consisted only of individuals from another cluster, which formed a single large and panmictic population, resembling a distinct “supercolony” in Northern China. The other two populations from Yunnan consisted of individuals from both clusters. The possible routes of spread of the recently established populations of E. lanigerum in China were revealed as follows: 1) the populations in Northern China (including these from Henan, Hebei, Shanxi, Shannxi, Jiangsu, and Gansu) may have been introduced from Shandong or Liaoning Provinces; 2) the populations in Yunnan consisted of an early-established population and a population introduced secondarily from Shandong or neighboring areas, indicating that the population in Yunnan has at least two sources; and 3) the recently established populations of E. lanigerum in Xinjiang might not have been introduced from the “supercolony” in Northern China. Knowledge of these routes of spread is useful for avoiding further dissemination and/or additional introductions.

Phylogenetic analysis and rapid identification of the whitefly, Bemisia afer, in China.

Abstract The phylogenetic relationship between the whitefly Bemisia afer (Priesner & Hosny) (Hemiptera: Aleyrodidae) from China and other populations among the world were analyzed based on the mitochondrial cytochrome oxidase I (mtCOI) gene. Phylogenetic analysis of mtCOI sequences and those of reference B. afer sequences showed that the populations of the species could be separated into 5 clades (I–V). There were at least two clades of the species from China (IV and V). These data suggested that B. afer might be a species complex. The Chinese B. afer populations were most divergent with B. afer from the United Kingdom and African countries. The distance between the Chinese B. afer (IV and V) and clades I, II, and III is more than 32%, while the distance among clades I, II, III is lower than 7.7%. A new set of primers specific to B. afer was designed to amplify a region of approximately 400 bp to discriminate B. afer from other Bemisia species in China based on mtCOI sequences.