Variation in both host defense and prior herbivory can alter plant-vector-virus interactions.

BACKGROUND: While virus-vector-host interactions have been a major focus of both basic and applied ecological research, little is known about how different levels of plant defense interact with prior herbivory to affect these relationships. We used genetically-modified strains of tomato (Solanum lycopersicum) varying in the jasmonic acid (JA) plant defense pathways to explore how plant defense and prior herbivory affects a plant virus (tomato yellow leaf curl virus, 'TYLCV'), its vector (the whitefly Bemisia tabaci MED), and the host. RESULTS: Virus-free MED preferred low-JA over high-JA plants and had lower fitness on high-JA plants. Viruliferous MED preferred low-JA plants but their survival was unaffected by JA levels. While virus-free MED did not lower plant JA levels, viruliferous MED decreased both JA levels and the expression of JA-related genes. Infestation by viruliferous MED reduced plant JA levels. In preference tests, neither virus-free nor viruliferous MED discriminated among JA-varying plants previously exposed to virus-free MED. However, both virus-free and viruliferous MED preferred low-JA plant genotypes when choosing between plants that had both been previously exposed to viruliferous MED. The enhanced preference for low-JA genotypes appears linked to the volatile compound neophytadiene, which was found only in whitefly-infested plants and at concentrations inversely related to plant JA levels. CONCLUSIONS: Our findings illustrate how plant defense can interact with prior herbivory to affect both a plant virus and its whitefly vector, and confirm the induction of neophytadiene by MED. The apparent attraction of MED to neophytadiene may prove useful in pest detection and management.

Long noncoding RNA PVT1 inhibits interferon-α mediated therapy for hepatocellular carcinoma cells by interacting with signal transducer and activator of transcription 1.

Long noncoding RNA (LncRNA) PVT1 has recently been reported to be involved in the development of hepatocellular carcinoma (HCC) and hsigh expression of oncogenic PVT1 is associated with poor prognosis of HCC. Interferon-α (IFN-α) has been used in clinic for HCC therapy. However, whether PVT1 is involved in the IFN-α therapy for HCC is completely unknown. Our study found that high PVT1 expression in HCC cells is associated with high unmethylation in PVT1 promoter region. IFN-α treatment further increases PVT1 expression in HCC cells by enhancing H3K4me3 modification on the promoter. Furthermore, PVT1 knockdown enhances IFN-α-induced HCC cell apoptosis by promoting phosphorylation of signal transducer and activator of transcription 1 (STAT1) and upregulating IFN-stimulated genes expression. Moreover, PVT1 specifically interacts with STAT1 in HCC cells. Taken together, these results for the first time indicate that IFN-α treatment promotes oncogenic PVT1 expression in HCC cells, which interacts with STAT1 to inhibit IFN-α signaling, ultimately blocking IFN-α-induced cells apoptosis, suggesting that lncRNA PVT1 may be a potential target to improve IFN-α-mediated HCC immunotherapies.

Multiple forms of vector manipulation by a plant-infecting virus: Bemisia tabaci and tomato yellow leaf curl virus.

For many insect-vectored plant viruses, the relationship between feeding behavior and vector competence may prove integral to an understanding of the epidemiology of the resulting plant disease. While plant-infecting viruses are well known to change host plant physiology in a way that makes them more attractive to vectors, viral manipulation of the vectors themselves has only recently been reported. Previous research suggested that the rapid spread of Tomato yellow leaf curl virus (TYLCV) throughout China has been facilitated by its primary vector, the whitefly Bemisia tabaci. We conducted two experiments testing the impact of TYLCV infection of the host plant (tomato) and vector (B. tabaci biotypes B and Q) on whitefly feeding behavior. Whiteflies of biotypes B and Q both appeared to find TYLCV-infected plants more attractive, probing them more quickly and having a greater number of feeding bouts; this did not, however, alter the total time spent feeding. Viruliferous whiteflies fed more readily than uninfected whiteflies and spent more time salivating into sieve tube elements. Because vector salivation is essential for viral transmission, this virally mediated alteration of behavior should provide TYLCV a direct fitness benefit. This is the first report of such manipulation by a nonpropagative virus that belongs to an exclusively plant-infecting family of viruses (Geminiviridae). In the context of previous research showing that feeding on TYLCV-infected plants harms biotype B but helps biotype Q, the fact that both biotypes were equally affected by TYLCV also suggests that the virus may alter the biotype B-biotype Q competitive interaction in favor of biotype Q.

Abnormal changes in metabolites caused by m6A methylation modification: The leading factors that induce the formation of immunosuppressive tumor microenvironment and their promising potential for clinical application.

BACKGROUND: N6-methyladenosine (m6A) RNA methylation modifications have been widely implicated in the metabolic reprogramming of various cell types within the tumor microenvironment (TME) and are essential for meeting the demands of cellular growth and maintaining tissue homeostasis, enabling cells to adapt to the specific conditions of the TME. An increasing number of research studies have focused on the role of m6A modifications in glucose, amino acid and lipid metabolism, revealing their capacity to induce aberrant changes in metabolite levels. These changes may in turn trigger oncogenic signaling pathways, leading to substantial alterations within the TME. Notably, certain metabolites, including lactate, succinate, fumarate, 2-hydroxyglutarate (2-HG), glutamate, glutamine, methionine, S-adenosylmethionine, fatty acids and cholesterol, exhibit pronounced deviations from normal levels. These deviations not only foster tumorigenesis, proliferation and angiogenesis but also give rise to an immunosuppressive TME, thereby facilitating immune evasion by the tumor. AIM OF REVIEW: The primary objective of this review is to comprehensively discuss the regulatory role of m6A modifications in the aforementioned metabolites and their potential impact on the development of an immunosuppressive TME through metabolic alterations. KEY SCIENTIFIC CONCEPTS OF REVIEW: This review aims to elaborate on the intricate networks governed by the m6A-metabolite-TME axis and underscores its pivotal role in tumor progression. Furthermore, we delve into the potential implications of the m6A-metabolite-TME axis for the development of novel and targeted therapeutic strategies in cancer research.

Demethylases in tumors and the tumor microenvironment: Key modifiers of N6-methyladenosine methylation.

RNA methylation modifications are widespread in eukaryotes and prokaryotes, with N6-methyladenosine (m6A) the most common among them. Demethylases, including Fat mass and obesity associated gene (FTO) and AlkB homolog 5 (ALKBH5), are important in maintaining the balance between RNA methylation and demethylation. Recent studies have clearly shown that demethylases affect the biological functions of tumors by regulating their m6A levels. However, their effects are complicated, and even opposite results have appeared in different articles. Here, we summarize the complex regulatory networks of demethylases, including the most important and common pathways, to clarify the role of demethylases in tumors. In addition, we describe the relationships between demethylases and the tumor microenvironment, and introduce their regulatory mechanisms. Finally, we discuss evaluation of demethylases for tumor diagnosis and prognosis, as well as the clinical application of demethylase inhibitors, providing a strong basis for their large-scale clinical application in the future.

Two horizontally acquired bacterial genes steer the exceptionally efficient and flexible nitrogenous waste cycling in whiteflies.

Nitrogen is an essential element for all life on earth. Nitrogen metabolism, including excretion, is essential for growth, development, and survival of plants and animals alike. Several nitrogen metabolic processes have been described, but the underlying molecular mechanisms are unclear. Here, we reveal a unique process of nitrogen metabolism in the whitefly Bemisia tabaci, a global pest. We show that it has acquired two bacterial uricolytic enzyme genes, B. tabaci urea carboxylase (BtUCA) and B. tabaci allophanate hydrolase (BtAtzF), through horizontal gene transfer. These genes operate in conjunction to not only coordinate an efficient way of metabolizing nitrogenous waste but also control B. tabaci's exceptionally flexible nitrogen recycling capacity. Its efficient nitrogen processing explains how this important pest can feed on a vast spectrum of plants. This finding provides insight into how the hijacking of microbial genes has allowed whiteflies to develop a highly economic and stable nitrogen metabolism network and offers clues for pest management strategies.

Two cytochrome P450 genes are involved in imidacloprid resistance in field populations of the whitefly, Bemisia tabaci, in China.

The sweet potato whitefly, Bemisia tabaci (Gennadius) (Hemiptera:Aleyrodidae), is an invasive and damaging pest of field crops worldwide. The neonicotinoid insecticide imidacloprid has been widely used to control this pest. We assessed the species composition (B vs. Q), imidacloprid resistance, and association between imidacloprid resistance and the expression of five P450 genes for 14-17 B. tabaci populations in 12 provinces in China. Fifteen of 17 populations contained only B. tabaci Q, and two populations contained both B and Q. Seven of 17 populations exhibited moderate to high resistance to imidacloprid, and eight populations exhibited low resistance to imidacloprid, compared with the most susceptible field WHHB population. In a study of 14 of the populations, resistance level was correlated with the expression of the P450 genes CYP6CM1 and CYP4C64 but not with the expression of CYP6CX1, CYP6CX4, or CYP6DZ7. This study indicates that B. tabaci Q has a wider distribution in China than previously reported. Resistance to imidacloprid in field populations of B. tabaci is associated with the increased expression of two cytochrome P450 genes (CYP6CM1 and CYP4C64).

Tomato spotted wilt virus infection reduces the fitness of a nonvector herbivore on pepper.

Plant pathogens and insect herbivores often share hosts under natural conditions. Hence, pathogen-induced changes in a host plant can affect the herbivore and vice versa. Even though plant viruses are ubiquitous in the field, little is known about plant-mediated interactions between viruses and nonvector herbivores. Here we tested whether the performance of the sweet potato whitefly, Bemisia tabaci (Gennadius) biotype Q, was altered when raised on pepper infected with Tomato spotted wilt virus (TSWV). TSWV infection reduced B. tabaci fecundity and longevity and increased B. tabaci developmental time but did not affect the insect's survival or female body lengths. Our results demonstrate that TSWV infection can decrease the fitness of B. tabaci biotype Q on pepper plants.

Gene expression profiling in the thiamethoxam resistant and susceptible B-biotype sweetpotato whitefly, Bemisia tabaci.

Thiamethoxam has been used as a major insecticide to control the B-biotype sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Due to its excessive use, a high level of resistance to thiamethoxam has developed worldwide over the past several years. To better understand the molecular mechanisms underlying this resistance in B. tabaci, gene profiles between the thiamethoxam-resistant and thiamethoxam-susceptible strains were investigated using the suppression subtractive hybridization (SSH) library approach. A total of 72 and 52 upand down-regulated genes were obtained from the forward and reverse SSH libraries, respectively. These expressed sequence tags (ESTs) belong to several functional categories based on their gene ontology annotation. Some categories such as cell communication, response to abiotic stimulus, lipid particle, and nuclear envelope were identified only in the forward library of thiamethoxam-resistant strains. In contrast, categories such as behavior, cell proliferation, nutrient reservoir activity, sequence-specific DNA binding transcription factor activity, and signal transducer activity were identified solely in the reverse library. To study the validity of the SSH method, 16 differentially expressed genes from both forward and reverse SSH libraries were selected randomly for further analyses using quantitative realtime PCR (qRT-PCR). The qRT-PCR results were fairly consistent with the SSH results; however, only 50% of the genes showed significantly different expression profiles between the thiamethoxam-resistant and thiamethoxam-susceptible whiteflies. Among these genes, a putative NAD-dependent methanol dehydrogenase was substantially over-expressed in the thiamethoxamresistant adults compared to their susceptible counterparts. The distributed profiles show that it was highly expressed during the egg stage, and was most abundant in the abdomen of adult females.

Multi-omics association analysis reveals interactions between the oropharyngeal microbiome and the metabolome in pediatric patients with influenza A virus pneumonia.

Children are at high risk for influenza A virus (IAV) infections, which can develop into severe illnesses. However, little is known about interactions between the microbiome and respiratory tract metabolites and their impact on the development of IAV pneumonia in children. Using a combination of liquid chromatography tandem mass spectrometry (LC-MS/MS) and 16S rRNA gene sequencing, we analyzed the composition and metabolic profile of the oropharyngeal microbiota in 49 pediatric patients with IAV pneumonia and 42 age-matched healthy children. The results indicate that compared to healthy children, children with IAV pneumonia exhibited significant changes in the oropharyngeal macrobiotic structure (p = 0.001), and significantly lower microbial abundance and diversity (p < 0.05). These changes came with significant disturbances in the levels of oropharyngeal metabolites. Intergroup differences were observed in 204 metabolites mapped to 36 metabolic pathways. Significantly higher levels of sphingolipid (sphinganine and phytosphingosine) and propanoate (propionic acid and succinic acid) metabolism were observed in patients with IAV pneumonia than in healthy controls. Using Spearman's rank-correlation analysis, correlations between IAV pneumonia-associated discriminatory microbial genera and metabolites were evaluated. The results indicate significant correlations and consistency in variation trends between Streptococcus and three sphingolipid metabolites (phytosphingosine, sphinganine, and sphingosine). Besides these three sphingolipid metabolites, the sphinganine-to-sphingosine ratio and the joint analysis of the three metabolites indicated remarkable diagnostic efficacy in children with IAV pneumonia. This study confirmed significant changes in the characteristics and metabolic profile of the oropharyngeal microbiome in pediatric patients with IAV pneumonia, with high synergy between the two factors. Oropharyngeal sphingolipid metabolites may serve as potential diagnostic biomarkers of IAV pneumonia in children.

Further spread of and domination by Bemisia tabaci (Hemiptera: Aleyrodidae) biotype Q on field crops 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.

Sulfoxaflor Alters Bemisia tabaci MED (Hemiptera: Aleyrodidae) Preference, Feeding, and TYLCV Transmission.

Many damaging agricultural pests can, in addition to their direct feeding damage, acquire and transmit plant pathogens. Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is considered a 'supervector' of disease-causing plant pathogens and viruses. One of the most damaging of these is Tomato yellow leaf curl virus (TYLCV), a circulatively transmitted begomovirus than can extensively damage field and greenhouse crops. Because sustained feeding periods are necessary to acquire and transmit circulatively transmitted viruses, pesticides that, in addition to their direct lethality, suppress feeding in surviving individuals may be particularly effective in decreasing viral transmission. We assessed the impact of sulfoxaflor, a sulfoximine insecticide, on the settling preference, feeding, and viral transmission of TYLCV-carrying B. tabaci on tomato. We found that viruliferous B. tabaci avoided both settling and feeding on sulfoxaflor-treated plants, and that sulfoxaflor virtually eliminated the transmission of TYLCV by B. tabaci. The antifeedant properties of sulfoxaflor have previously been reported in other pest systems; our results document similar effects on viruliferous B. tabaci and demonstrate that this pesticide can reduce TYLCV transmission by surviving individuals.

Lethal and Sublethal Effects of Flupyradifurone on Bemisia tabaci MED (Hemiptera: Aleyrodidae) Feeding Behavior and TYLCV Transmission in Tomato.

Pesticides primarily affect target organisms via direct toxicity, but may also alter the feeding behaviors of surviving individuals in ways that alter their effect on host plants. The latter impact is especially important when pests can transmit plant pathogens. The Mediterranean (MED) population of the sweetpotato whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) transmits Tomato yellow leaf curl virus (TYLCV), a pathogen that can be economically devastating in field and greenhouse cropping systems. We first assessed the impact of sublethal (LC15) and label concentrations of flupyradifurone, a butenolide-derived insecticide, on the feeding behavior of TYLCV-infected MED on tomato. We next measured the effect of flupyradifurone on plant TYLCV load, vector transmission efficiency, and MED survival. Both the LC15 and label flupyradifurone concentrations dramatically altered MED feeding and caused the near cessation of both salivation and phloem ingestion (necessary for viral transmission and acquisition, respectively). Both concentrations also significantly reduced plant TYLCV load, and the label rate of flupyradifurone sharply decreased TYLCV transmission while killing >99% of MED. As the first report of pesticide-induced changes in the feeding behavior of viruliferous Bemisia, our findings highlight the potential importance of chemically driven feeding cessation in the control of TYLCV and other Bemisia-transmitted plant pathogens.

Annual analysis of field-evolved insecticide resistance in Bemisia tabaci across China.

BACKGROUND: Over recent decades, many efficacious insecticides have been applied for control of Bemisia tabaci, one of the most notorious insect pests worldwide. Field-evolved insecticide resistance in B. tabaci has developed globally, but remains poorly understood in China. RESULTS: In this study, a total of 30 field samples of the whitefly Bemisia tabaci from eight provinces of China were collected in 2015 to 2018. Twenty-four of the populations were identified as Mediterranean, 'Q' type (MED), three were Middle East-Asia Minor 1, 'B' type (MEAM1), and three were mixtures of MED/ MEAM1. After identifying whether they belong to MED or MEAM1, the selected individuals were used in bioassays assessing insecticide resistance to abamectin, thiamethoxam, spirotetramat, cyantraniliprole, and pyriproxyfen. Our results showed that all populations in the eight regions had little or no resistance to abamectin; abamectin resistance was highest in the Hunan (Changsha) and Hubei (Wuhan) regions and was lowest in the island region of Hainan (Sanya). The resistance of B. tabaci to spirotetramat, cyantraniliprole, and pyriproxyfen increased each year. The resistance to thiamethoxam remained low because of the high LC50 value for the laboratory strain. CONCLUSION: These findings suggest that a rotation system using efficacious B. tabaci insecticides with differing mode of actions ought to be implemented for sustainable control to reduce the potential of resistance development. This study provides important data to support the integrated pest management and insecticide resistance management of B. tabaci in China. © 2021 Society of Chemical Industry.

Tomato Yellow Leaf Curl Virus Infection Alters Bemisia tabaci MED (Hemiptera: Aleyrodidae) Vulnerability to Flupyradifurone.

The whitefly, Bemisia tabaci Gennadius, is a major phloem-feeding pest of agricultural crops that is also an important vector of many plant diseases. The B. tabaci Mediterranean ('MED') biotype is a particularly effective vector of Tomato yellow leaf curl virus (TYLCV), a devastating plant pathogen. Although insecticides play an important role in the control of MED and TYLCV, little is known about how TYLCV infection affects MED susceptibility to insecticides. We conducted research addressing how MED susceptibility to flupyradifurone, the first commercially available systemic control agent derived from the butenolide class of insecticides, was affected by TYLCV infection. We first conducted bioassays determining the LC15 and LC50 for control and viruliferous MED feeding on either water- or insecticide-treated plants. We next measured several demographic parameters of control and viruliferous MED exposed to either insecticide- or water-treated plants. TYLCV infection increased MED tolerance of flupyradifurone: the LC15 and LC50 of viruliferous MED were double that of uninfected MED. Viral infection also altered MED demographic responses to flupyradifurone, but in an inconsistent manner. Although the ability of TYLCV and other persistently transmitted viruses to benefit Bemisia via manipulation of host plant defense is well known, this appears to be the first example of virally mediated changes in vector susceptibility to an insecticide.

Botanical Volatiles Selection in Mediating Electrophysiological Responses and Reproductive Behaviors for the Fall Webworm Moth Hyphantria cunea.

Host-plant volatiles play vital roles for insects to locate foraging, mating, and oviposition sites in the environment. As one of the devastating invasive forestry pests, Hyphantria cunea causes a great annual loss in China, and understanding its chemical ecology is an important task. The current research was done in terms of chemical analysis, electrophysiology, and behavioral assays on H. cunea to assess its olfactory reception toward host-plant volatiles. A screen of possible common host volatiles was done, targeting on five favored hosts of H. cunea, harvesting six potential bioactive compounds from a total of 78 odorant components. Six types of antennal sensilla were investigated on their distributions on the antennae, and sexual dimorphism was described. H. cunea showed responses to all selected host-related volatiles in electroantennogram tests, and linalyl butyrate elicited the strongest responses. Furthermore, mating rates in adult pairs that are exposed to dibutyl phthalate and phytol have been significantly increased, while oviposition rates and female fecundity were not influenced. The results of the current study provide initial evidence showing that universal host-derived volatile cues are essential for H. cunea moth in terms of mating, which can also provide insights into the development of botanical attractants.

Feeding behavior explains the different effects of cabbage on MEAM1 and MED cryptic species of Bemisia tabaci.

MEAM1 (Middle East-Asia Minor 1, "B" biotype) and MED (Mediterranean, "Q" biotype) are the two most destructive cryptic species of the Bemisia tabaci complex on the planet. Our previous studies have shown that MEAM1 outcompetes MED on cabbage; the underlying mechanism is unknown. In the Brassicaceae family, the glucosinolate-myrosinase defense system plays a crucial role in deterring feeding, inhibiting growth, and causing acute toxicity against a wide range of generalist herbivores. In the present study, we first compared the survival of MEAM1 and MED exposed to sinigrin (a glucosinolate) and myrosinase (an enzyme that degrades glucosinolates); we found that survival of both species was high in response to sinigrin alone but was near zero in response to sinigrin + myrosinase. We then used electropenetrography (electrical penetration graphs, EPG) to assess the feeding behaviors of MEAM1 and MED whiteflies on cabbage. The EPG results revealed that the mean duration of each potential drop (pd, indicating an intracellular puncture) was substantially longer for MED than MEAM1 on cabbage, indicating that the exposure to the toxic hydrolysates of glucosinolate and myrosinase is greater for MED than for MEAM1. We therefore conclude that differences in penetrating behaviors may help explain the different effects of cabbage on MEAM1 and MED whitefly species.

Transmission of Tomato Yellow Leaf Curl Virus by Bemisia tabaci as Affected by Whitefly Sex and Biotype.

Bemisia tabaci is a serious pest of vegetables and other crops worldwide. The most damaging and predominant B. tabaci biotypes are B and Q, and both are vectors of tomato yellow leaf curl virus (TYLCV). Previous research has shown that Q outperforms B in many respects but comparative research is lacking on the ability of B and Q to transmit viruses. In the present study, we tested the hypothesis that B and Q differ in their ability to transmit TYLCV and that this difference helps explain TYLCV outbreaks. We compared the acquisition, retention, and transmission of TYLCV by B and Q females and males. We found that Q females are more efficient than Q males, B females, and B males at TYLCV acquisition and transmission. Although TYLCV acquisition and transmission tended to be greater for B females than B males, the differences were not statistically significant. Based on electrical penetration graphs determination of phloem sap ingestion parameters, females fed better than males, and Q females fed better than Q males, B females, or B males. These results are consistent with the occurrences of TYLCV outbreaks in China, which have been associated with the spread of Q rather than B.

The endosymbiont Hamiltonella increases the growth rate of its host Bemisia tabaci during periods of nutritional stress.

The whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) harbors several bacterial symbionts. Among the secondary (facultative) symbionts, Hamiltonella has high prevalence and high infection frequencies, suggesting that it may be important for the biology and ecology of its hosts. Previous reports indicated that Hamiltonella increases whitefly fitness and, based on the complete sequencing of its genome, may have the ability to synthesize cofactors and amino acids that are required by its host but that are not sufficiently synthesized by the host or by the primary endosymbiont, Portiera. Here, we assessed the effects of Hamiltonella infection on the growth of B. tabaci reared on low-, standard-, or high-nitrogen diets. When B. tabaci was reared on a standard-nitrogen diet, no cost or benefit was associated with Hamiltonella infection. But, if we reared whiteflies on low-nitrogen diets, Hamiltonella-infected whiteflies often grew better than uninfected whiteflies. Furthermore, nitrogen levels in field-collected whiteflies indicated that the nutritional conditions in the field were comparable to the low-nitrogen diet in our laboratory experiment. These data suggest that Hamiltonella may play a previously unrecognized role as a nutritional mutualist in B. tabaci.

Insect symbiont facilitates vector acquisition, retention, and transmission of plant virus.

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.