Background Tomato yellow leaf curl virus (TYLCV) was introduced into China in 2006, approximately 10 years after the introduction of an invasive whitefly, Bemisia tabaci (Genn.) B biotype. Even so the distribution and prevalence of TYLCV remained limited, and the economic damage was minimal. Following the introduction of Q biotype into China in 2003, the prevalence and spread of TYLCV started to accelerate. This has lead to the hypothesis that the two biotypes might not be equally competent vectors of TYLCV.Methodology/Principal FindingsThe infection frequency of TYLCV in the field-collected B. tabaci populations was investigated, the acquisition and transmission capability of TYLCV by B and Q biotypes were compared under the laboratory conditions. Analysis of B. tabaci populations from 55 field sites revealed the existence of 12 B and 43 Q biotypes across 18 provinces in China. The acquisition and transmission experiments showed that both B and Q biotypes can acquire and transmit the virus, however, Q biotype demonstrated superior acquisition and transmission capability than its B counterparts. Specifically, Q biotype acquired significantly more viral DNA than the B biotype, and reached the maximum viral load in a substantially shorter period of time. Although TYLCV was shown to be transmitted horizontally by both biotypes, Q biotype exhibited significantly higher viral transmission frequency than B biotype. Vertical transmission result, on the other hand, indicated that TYLCV DNA can be detected in eggs and nymphs, but not in pupae and adults of the first generation progeny.Conclusions/SignificanceThese combined results suggested that the epidemiology of TYLCV was aided differentially by the two invasive whiteflies (B and Q biotypes) through horizontal but not vertical transmission of the virus. This is consistent with the concomitant eruption of TYLCV in tomato fields following the recent rapid invasion of Q biotype whitefly in China.

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), causes severe crop losses to many crops. The worst of these losses are often associated with the invasion and establishment of biotypes B and Q of this pest. Previous research in 2007 showed that biotype Q occurred with other biotypes in most field populations in China. To determine the current status of the biotype composition in the field, an extensive survey covering mainly eastern parts of China was conducted in 2009. Using polymerase chain reaction primers specific for the mitochondrial cytochrome oxidase I of biotypes B and Q and gene sequencing, we determined the biotypes composition in 61 whitefly populations and their distribution across 19 provinces in China. Our research revealed that only biotypes B and Q have been found in the field in 2009 in China. Among them, biotype Q was dominant in 44 locations (100.0%) and biotype B was dominant in 17 locations (100.0%). The current survey indicates that biotype Q has rapidly displaced biotype B in most locations in China.

Summary 1.Maternally inherited bacterial symbionts are present in many, if not most, insect species. While there is rapidly accumulating evidence that facultative, heritable symbionts often protect insect hosts from natural enemies, there have been few clear examples where facultative symbionts mediate herbivore-plant interactions. 2. The phloem-feeding whitefly, Bemisia tabaci, is a major agricultural pest that frequently harbours facultative symbionts, including Hamiltonella defensa. While H. defensa and other facultative symbionts have been shown to improve whitefly performance on particular food plants, no direct and specific roles for symbiont-mediated interactions with food plants have been identified. 3. Here, we conducted a series of assays to determine whether infection with H. defensa improved whitefly performance on tomato (Solanum lycopersicum) and whether this benefit was associated with symbiont effects on induced plant defences. Finally, we tested whether impacts on induced defences involved in the modulation of a salivary factor. 4. The downregulation of plant defences was associated with increased whitefly fecundity and survival. Feeding by H. defensa-infected whiteflies suppressed JA and JA-related anti-herbivore-induced defences in tomato relative to uninfected controls. That saliva-only treatments of damaged tomato leaves from H. defensa-infected whiteflies suppressed induced plant defences compared to saliva from uninfected controls, suggesting that elicitors in saliva were responsible. Characterization of the putative salivary factor(s) revealed they are likely small (< 3-kDa) and nonproteinaceous. 5. Interestingly, suppression of defences was not observed in SA-deficient NahG plants, indicating that suppression of JA-regulated defences depends on the SA signalling pathway. This finding reveals an intriguing example of the crosstalk between SA and JA signalling pathways and suggests that infection with facultative symbionts can result in the manipulation of induced plant defences to the benefit of the insect host and heritable symbiont. 6. Our results show that the bacterial symbiont H. defensa mediates whitefly-plant interactions by suppressing induced plant defences in tomato. This finding is among the first showing a direct role for facultative symbionts in mediating plant-herbivore interactions and demonstrates a novel tactic for insect herbivores to circumvent plant defences. Symbiont-mediated suppression of plant defences may enhance the deleterious effects of insect pests feeding on important crops.

The present studies were carried out to evaluate resistance in the populations of Spodoptera litura Fab. (Lepidoptera, Noctuidae) from five districts of Hunan Province in China to various insecticides from 2010 to 2012 using a standard leaf dip bioassay method. For organophosphates and pyrethroids, resistance ratios compared with a susceptible Lab-BJ strain were in the range of 14–229-fold for organophosphates and 12–227-fold for pyrethroids. Similarly, relative low levels of resistance to emamectin, indoxacarb, and chlorfenapyr were observed in all five populations. In contrast, the resistance to carbamates (thiodicarb or methomyl) was significantly higher than that of organophosphates, pyrethroids and newer chemistry insecticides. The pairwise correlation coefficients of LC50 values indicated that the newer chemistry insecticides and old generation insecticides were not significant except abamectin, which was negatively significantly correlated with methomyl. A significant correlation was observed between thiodicarb, methomyl, and deltamethrin, whereas resistance to bifenthrin showed no correlations with resistance to other insecticides except deltamethrin. The results are discussed in relation to integrated pest management for S. litura with special reference to management of field evolved resistance to insecticides.

Tomato yellow leaf curl virus (TYLCV) was first detected in China in 2006, following the introduction of Bemisia tabaci Q into China in 2003. Since then, the incidence of TYLCV in tomato fields in China has greatly increased as has the abundance and distribution of Q whiteflies containing the bacterial symbiont Hamiltonella with high frequency. This suggested that the symbiont Hamiltonella might associate with the transmission efficiency of TYLCV by the whitefly vector. Here we report the first evidence that the Hamiltonella is closely associated with the acquisition, retention, and transmission efficiency of TYLCV by the whitefly vector. Our findings combined with the outbreaks of TYLCV following the introduction of Q, provided an explanation for why Hamiltonella is being maintained at a relatively high level in Chinese B. tabaci Q and also have implications for disease and vector management.

Bemisia tabaci, the whitefly vector of Tomato yellow leaf curl virus (TYLCV), seriously reduces tomato production and quality. Here, we report the first evidence that infection by TYLCV alters the host preferences of invasive B. tabaci B (Middle East-Minor Asia 1) and Q (Mediterranean genetic group), in which TYLCV-free B. tabaci Q preferred to settle on TYLCV-infected tomato plants over healthy ones. TYLCV-free B. tabaci B, however, preferred healthy tomato plants to TYLCV-infected plants. In contrast, TYLCV-infected B. tabaci, either B or Q, did not exhibit a preference between TYLCV-infected and TYLCV-free tomato plants. Based on gas chromatography-mass spectrometry (GCMS)analysis of plant terpene volatiles, significantly more β-myrcene, thymene, β-phellandrene, caryophyllene, (+)-4-carene, and α-humulene were released from the TYLCV-free tomato plants than from the TYLCV-infected ones. The results indicate TYLCV can alter the host preferences of its vector Bemisia tabaci B and Q.

The initiation and progression of diffuse large B-cell lymphoma (DLBCL) is governed by genetic and epigenetic aberrations. As the most abundant eukaryotic message RNA modification, N6-methyladenosine (m6A) is known to influence various fundamental bioprocesses by regulating target gene; however, the function of m6A modifications in DLBCL is unclear. PIWI-interacting RNAs (piRNAs) have been indicated to be epigenetic effectors in cancer. Here, we show that high expression of piRNA-30473 supports the aggressive phenotype of DLBCL, and piRNA-30473 depletion decreases proliferation and induces cell cycle arrest in DLBCL cells. In xenograft DLBCL models, piRNA-30473 inhibition reduces tumor growth. Moreover, piRNA-30473 is significantly associated with overall survival (OS) in a univariate analysis, and is statistically significant after adjusting for the National Comprehensive Cancer Network-International Prognostic Index (NCCN-IPI) in the multivariate analysis. Additional studies demonstrate that piRNA-30473 exerts its oncogenic role through a mechanism involving the upregulation of WTAP, an m6A mRNA methylase, thus enhances the global m6A level. Integrating transcriptome and m6A-seq analyses reveal that WTAP increases the expression of its critical target gene HK2 by enhancing the HK2 m6A level, thereby promoting the progression of DLBCL. Together, the piRNA-30473/WTAP/HK2 axis contributes to tumorigenesis by regulating m6A RNA methylation in DLBCL. Furthermore, by comprehensively analyzing our clinical data and datasets, we discover that the m6A regulatory genes piRNA-30473 and WTAP improve survival prediction in DLBCL patients. Our study highlights the functional importance of the m6A modification in DLBCL and might assist in the development of a prognostic stratification and therapeutic approach for DLBCL.

Background Bemisia tabaci (Gennadius) is a phloem-feeding insect poised to become one of the major insect pests in open field and greenhouse production systems throughout the world. The high level of resistance to insecticides is a main factor that hinders continued use of insecticides for suppression of B. tabaci. Despite its prevalence, little is known about B. tabaci at the genome level. To fill this gap, an invasive B. tabaci B biotype was subjected to pyrosequencing-based transcriptome analysis to identify genes and gene networks putatively involved in various physiological and toxicological processes.Methodology and Principal FindingsUsing Roche 454 pyrosequencing, 857,205 reads containing approximately 340 megabases were obtained from the B. tabaci transcriptome. De novo assembly generated 178,669 unigenes including 30,980 from insects, 17,881 from bacteria, and 129,808 from the nohit. A total of 50,835 (28.45%) unigenes showed similarity to the non-redundant database in GenBank with a cut-off E-value of 10–5. Among them, 40,611 unigenes were assigned to one or more GO terms and 6,917 unigenes were assigned to 288 known pathways. De novo metatranscriptome analysis revealed highly diverse bacterial symbionts in B. tabaci, and demonstrated the host-symbiont cooperation in amino acid production. In-depth transcriptome analysis indentified putative molecular markers, and genes potentially involved in insecticide resistance and nutrient digestion. The utility of this transcriptome was validated by a thiamethoxam resistance study, in which annotated cytochrome P450 genes were significantly overexpressed in the resistant B. tabaci in comparison to its susceptible counterparts.ConclusionsThis transcriptome/metatranscriptome analysis sheds light on the molecular understanding of symbiosis and insecticide resistance in an agriculturally important phloem-feeding insect pest, and lays the foundation for future functional genomics research of the B. tabaci complex. Moreover, current pyrosequencing effort greatly enriched the existing whitefly EST database, and makes RNAseq a viable option for future genomic analysis.