Incompatible and sterile insect techniques combined eliminate mosquitoes.

The radiation-based sterile insect technique (SIT) has successfully suppressed field populations of several insect pest species, but its effect on mosquito vector control has been limited. The related incompatible insect technique (IIT)-which uses sterilization caused by the maternally inherited endosymbiotic bacteria Wolbachia-is a promising alternative, but can be undermined by accidental release of females infected with the same Wolbachia strain as the released males. Here we show that combining incompatible and sterile insect techniques (IIT-SIT) enables near elimination of field populations of the world's most invasive mosquito species, Aedes albopictus. Millions of factory-reared adult males with an artificial triple-Wolbachia infection were released, with prior pupal irradiation of the released mosquitoes to prevent unintentionally released triply infected females from successfully reproducing in the field. This successful field trial demonstrates the feasibility of area-wide application of combined IIT-SIT for mosquito vector control.

Phylogenomics resolves the higher-level phylogeny of herbivorous eriophyoid mites (Acariformes: Eriophyoidea).

BACKGROUND: Eriophyoid mites (Eriophyoidea) are among the largest groups in the Acariformes; they are strictly phytophagous. The higher-level phylogeny of eriophyoid mites, however, remains unresolved due to the limited number of available morphological characters-some of them are homoplastic. Nevertheless, the eriophyoid mites sequenced to date showed highly variable mitochondrial (mt) gene orders, which could potentially be useful for resolving the higher-level phylogenetic relationships. RESULTS: Here, we sequenced and compared the complete mt genomes of 153 eriophyoid mite species, which showed 54 patterns of rearranged mt gene orders relative to that of the hypothetical ancestor of arthropods. The shared derived mt gene clusters support the monophyly of eriophyoid mites (Eriophyoidea) as a whole and the monophylies of six clades within Eriophyoidea. These monophyletic groups and their relationships were largely supported in the phylogenetic trees inferred from mt genome sequences as well. Our molecular dating results showed that Eriophyoidea originated in the Triassic and diversified in the Cretaceous, coinciding with the diversification of angiosperms. CONCLUSIONS: This study reveals multiple molecular synapomorphies (i.e. shared derived mt gene clusters) at different levels (i.e. family, subfamily or tribe level) from the complete mt genomes of 153 eriophyoid mite species. We demonstrated the use of derived mt gene clusters in unveiling the higher-level phylogeny of eriophyoid mites, and underlines the origin of these mites and their co-diversification with angiosperms.

The influence of Acetobacter pomorum bacteria on the developmental progression of Drosophila suzukii via gluconic acid secretion.

Insects are rich in various microorganisms, which play diverse roles in affecting host biology. Although most Drosophila species prefer rotten fruits, the agricultural pest Drosophila suzukii attacks ripening fruits before they are harvested. We have reported that the microbiota has positive and negative impacts on the agricultural pest D. suzukii on nutrient-poor and -rich diets, respectively. On nutrient-poor diets, microbes provide protein to facilitate larval development. But how they impede D. suzukii development on nutrient-rich diets is unknown. Here we report that Acetobacter pomorum (Apo), a commensal bacterium in many Drosophila species and rotting fruit, has several detrimental effects in D. suzukii. Feeding D. suzukii larvae nutrient-rich diets containing live Apo significantly delayed larval development and reduced the body weight of emerged adults. Apo induced larval immune responses and downregulated genes of digestion and juvenile hormone metabolism. Knockdown of these genes in germ-free larvae reproduced Apo-like weakened phenotypes. Apo was confirmed to secrete substantial amounts of gluconic acid. Adding gluconic acid to the D. suzukii larval diet hindered larval growth and decreased adult body weight. Moreover, the dose of gluconic acid that adversely affected D. suzukii did not negatively affect Drosophila melanogaster, suggesting that D. suzukii is less tolerant to acid than D. melanogaster. Taken together, these findings indicate that D. suzukii is negatively affected by gluconic acid, which may explain why it prefers ripening fruit over Apo-rich rotting fruit. These results show an insect's tolerance to microbes can influence its ecological niche.

A conserved protein disulfide isomerase enhances plant resistance against herbivores.

Herbivore-associated molecular patterns (HAMPs) enable plants to recognize herbivores and may help plants adjust their defense responses. Here, we report on herbivore-induced changes in a protein disulfide isomerase (PDI) widely distributed across arthropods. PDI from the spider mite Tetranychus evansi (TePDI), a mesophyll-feeding agricultural pest worldwide, triggered immunity in multiple Solanaceae plants. TePDI-mediated cell death in Nicotiana benthamiana required the plant signaling proteins SGT1 (suppressor of the G2 allele of skp1) and HSP90 (heat shock protein 90), but was suppressed by spider mite effectors Te28 and Te84. Moreover, PDIs from phylogenetically distinct herbivorous and nonherbivorous arthropods triggered plant immunity. Finally, although PDI-induced plant defenses impaired the performance of spider mites on plants, RNAi experiments revealed that PDI genes are essential for the survival of mites and whiteflies. Our findings indicate that plants recognize evolutionarily conserved HAMPs to activate plant defense and resist pest damage, pointing to opportunities for broad-spectrum pest management.

A new spider mite elicitor triggers plant defence and promotes resistance to herbivores.

Herbivore-associated elicitors (HAEs) are active molecules produced by herbivorous insects. Recognition of HAEs by plants induces defence that resist herbivore attacks. We previously demonstrated that the tomato red spider mite Tetranychus evansi triggered defence in Nicotiana benthamiana. However, our knowledge of HAEs from T. evansi remains limited. Here, we characterize a novel HAE, Te16, from T. evansi and dissect its function in mite-plant interactions. We investigate the effects of Te16 on spider mites and plants by heterologous expression, virus-induced gene silencing assay, and RNA interference. Te16 induces cell death, reactive oxygen species (ROS) accumulation, callose deposition, and jasmonate (JA)-related responses in N. benthamiana leaves. Te16-mediated cell death requires a calcium signalling pathway, cytoplasmic localization, the plant co-receptor BAK1, and the signalling components SGT1 and HSP90. The active region of Te16-induced cell death is located at amino acids 114-293. Moreover, silencing Te16 gene in T. evansi reduces spider mite survival and hatchability, but expressing Te16 in N. benthamiana leaves enhances plant resistance to herbivores. Finally, Te16 gene is specific to Tetranychidae species and is highly conserved in activating plant immunity. Our findings reveal a novel salivary protein produced by spider mites that elicits plant defence and resistance to insects, providing valuable clues for pest management.

Alzheimer-like behavior and synaptic dysfunction in 3 × Tg-AD mice are reversed with calcineurin inhibition.

Alzheimer's disease is a progressive neurodegenerative disorder characterized by impairments in synaptic plasticity and cognitive performance. Current treatments are unable to achieve satisfactory therapeutic effects or reverse the progression of the disease. Calcineurin has been implicated as part of a critical signaling pathway for learning and memory, and neuronal calcineurin may be hyperactivated in AD. To investigate the effects and underlying mechanisms of FK506, a calcineurin inhibitor, on Alzheimer-like behavior and synaptic dysfunction in the 3 × Tg-AD transgenic mouse model of Alzheimer's disease, we investigated the effect of FK506 on cognitive function and synaptic plasticity in the 3 × Tg-AD transgenic mouse model of Alzheimer's disease. The results showed that FK506 treatment ameliorated cognitive deficits, as indicated by the decreased latency in the water maze, and attenuated tau hyperphosphorylation in 3 × Tg-AD mice. Treatment with FK506 also reduced the levels of certain markers of postsynaptic deficits, including PSD-95 and NR2B, and reversed the long-term potentiation deficiency and dendritic spine impairments in 3 × Tg-AD mice. These findings suggest that treatment with calcineurin inhibitors such as FK506 can be an effective therapeutic strategy to rescue synaptic deficit and cognitive impairment in familial Alzheimer's disease and related tauopathies.

Macroevolutionary analyses point to a key role of hosts in diversification of the highly speciose eriophyoid mite superfamily.

The superfamily Eriophyoidea includes >5000 named species of very small phytophagous mites. As for many groups of phytophagous invertebrates, factors responsible for diversification of eriophyoid mites are unclear. Here, we used an inferred phylogeny of 566 putative species of eriophyoid mites based on fragments of two mitochondrial genes and two nuclear genes to examine factors associated with their massive evolutionary diversification through time. Our dated phylogeny indicates a Carboniferous origin for gymnosperm-associated Eriophyoidea with subsequent diversification involving multiple host shifts to angiosperms-first to dicots, and then to monocots or shifts back to gymnosperms-beginning in the Cretaceous period when angiosperms diverged. Speciation rates increased more rapidly in the Eriophyidae + Diptilomiopidae (mostly infesting angiosperms) than in the Phytoptidae (mostly infesting gymnosperms). Phylogenetic signal, speciation rates, dispersal and vicariance results combined with inferred topologies show that hosts played a key role in the evolution of eriophyoid mites. Speciation constrained by hosts was probably the main driver behind eriophyoid mite diversification worldwide. We demonstrate monophyly of the Eriophyoidea, whereas all three families, most subfamilies, tribes, and most genera are not monophyletic. Our time-calibrated tree provides a framework for further evolutionary studies of eriophyoid mites and their interactions with host plants as well as taxonomic revisions above the species level.

Environmental Factors and the Symbiont Cardinium Influence the Bacterial Microbiome of Spider Mites Across the Landscape.

Microbes play a key role in the biology, ecology, and evolution of arthropods. Despite accumulating data on microbial communities in arthropods that feed on plants using piercing-sucking mouthparts, we still lack a comprehensive understanding of the composition and assembly factors of the microbiota, particularly in field-collected spider mites. Here, we applied 16S rRNA amplicon sequencing to investigate the characters of the bacterial community in 140 samples representing 420 mite individuals, belonging to eight Tetranychus species (Acari: Tetranychidae) collected from 26 sites in China. The results showed that the bacterial composition of spider mites varied significantly among different species, locations, and plants. The environment showed a significant influence on the bacterial community of spider mites, with different relative contributions. Latitude and precipitation were found to be the main factors influencing the bacterial community composition. The dissimilarity of bacterial community and geographical distance between mite locations were significantly correlated. The assembly of spider mite bacterial communities seemed to be mainly influenced by stochastic processes. Furthermore, the symbiont Cardinium was found to be important in shaping the microbiota of many Tetranychus species. The relative abundance of Cardinium was > 50% in T. viennensis, T. urticae G, T. urticae R, and T. turkestani. Removing Cardinium reads from our analysis significantly changed Shannon diversity index and weighted beta diversity in these species. Altogether, this study provides novel insights into bacterial diversity patterns that contribute to our knowledge of the symbiotic relationships between arthropods and their bacterial communities.

Population genetics reveal multiple independent invasions of Spodoptera frugiperda (Lepidoptera: Noctuidae) in China.

The fall armyworm (Spodoptera frugiperda), a destructive pest that originated in South and North America, spread to China in early 2019. Controlling this invasive pest requires an understanding of its population structure and migration patterns, yet the invasion genetics of Chinese S. frugiperda is not clear. Here, using the mitochondrial cytochrome oxidase subunit I (COI) gene, triose phosphate isomerase (Tpi) gene and eight microsatellite loci, we investigated genetic structure and genetic diversity of 16 S. frugiperda populations in China. The Tpi locus identified most S. frugiperda populations as the corn-strains, and a few were heterozygous strains. The microsatellite loci revealed that the genetic diversity of this pest in China was lower than that in South America. Furthermore, we found moderate differentiation among the populations, distinct genetic structures between adjacent populations and abundant genetic resources in the S. frugiperda populations from China sampled across 2 years. The survival rate of S. frugiperda was significantly higher when it was fed on corn leaves than on rice leaves, and the larval stage mortality rate was the highest under both treatments. Our results showed that S. frugiperda probably invaded China via multiple independent introductions and careful pesticide control, continuous monitoring and further studies will be needed to minimize its potential future outbreak.

Comparative genome and transcriptome analyses reveal innate differences in response to host plants by two color forms of the two-spotted spider mite Tetranychus urticae.

BACKGROUND: The two-spotted spider mite, Tetranychus urticae, is a major agricultural pest with a cosmopolitan distribution, and its polyphagous habits provide a model for investigating herbivore-plant interactions. There are two body color forms of T. urticae with a different host preference. Comparative genomics and transcriptomics are used here to investigate differences in responses of the forms to host plants at the molecular level. Biological responses of the two forms sourced from multiple populations are also presented. RESULTS: We carried out principal component analysis of transcription changes in three red and three green T. urticae populations feeding on their original host (common bean), and three hosts to which they were transferred: cotton, cucumber and eggplant. There were differences among the forms in gene expression regardless of their host plant. In addition, different changes in gene expression were evident in the two forms when responding to the same host transfer. We further compared biological performance among populations of the two forms after feeding on each of the four hosts. Fecundity of 2-day-old adult females showed a consistent difference between the forms after feeding on bean. We produced a 90.1-Mb genome of the red form of T. urticae with scaffold N50 of 12.78 Mb. Transcriptional profiles of genes associated with saliva, digestion and detoxification showed form-dependent responses to the same host and these genes also showed host-specific expression effects. CONCLUSIONS: Our research revealed that forms of T. urticae differ in host-determined transcription responses and that there is form-dependent plasticity in the transcriptomic responses. These differences may facilitate the extreme polyphagy shown by spider mites, although fitness differences on hosts are also influenced by population differences unrelated to color form.

Two Newly Introduced Wolbachia Endosymbionts Induce Cell Host Differences in Competitiveness and Metabolic Responses.

Wolbachia endosymbionts can induce multiple reproductive manipulations in their hosts, with cytoplasmic incompatibility (CI) being one of the most common manipulations. Two important agricultural pests, the white-backed planthopper (Sogatella furcifera) and the brown planthopper (Nilaparvata lugens), are usually infected with CI-inducing Wolbachia strain wFur and non-CI-inducing Wolbachia strain wLug, respectively. The biological effects of these infections when present in a host cell are unknown. Here, we introduced the two Wolbachia strains into an Aedes albopictus cell line to stably establish a wFur-infected cell line (WFI) and a wLug-infected cell line (WLI). In a mixed culture, WFI cells were completely replaced by WLI cells, pointing to a stronger competitiveness of the WLI cell line. We found that infection by both Wolbachia strains reduced cell growth rates, but WLI had a higher cell growth rate than WFI, and this difference in cell growth rate combined with possible Wolbachia differences in diffusivity may have affected cell competitiveness. By examining gene expression and metabolites in the two lines, we found that some genes and key metabolites responded to differences in cell competitiveness. These results point to potential mechanisms that could contribute to the relative performance of hosts infected by these strains and also highlight the substantial impact of a non-CI Wolbachia on metabolism, which may in turn influence the fitness of its native host. IMPORTANCEWolbachia transinfection in insects can be used to suppress pests and block virus transmission. We stably introduced two Wolbachia strains from rice planthoppers into cell lines of an important arbovirus mosquito vector, Aedes albopictus. The levels of competitiveness of host cells from the lines infected by the two Wolbachia strains were different, as were metabolic responses of the cell lines. These results suggest potential metabolic effects of Wolbachia on native hosts that could be exploited when they are transinfected into novel hosts for pest control.

Tau accumulation triggers STAT1-dependent memory deficits by suppressing NMDA receptor expression.

Intracellular tau accumulation forming neurofibrillary tangles is hallmark pathology of Alzheimer's disease (AD), but how tau accumulation induces synapse impairment is elusive. By overexpressing human full-length wild-type tau (termed hTau) to mimic tau abnormality as seen in the brain of sporadic AD patients, we find that hTau accumulation activates JAK2 to phosphorylate STAT1 (signal transducer and activator of transcription 1) at Tyr701 leading to STAT1 dimerization, nuclear translocation, and its activation. STAT1 activation suppresses expression of N-methyl-D-aspartate receptors (NMDARs) through direct binding to the specific GAS element of GluN1, GluN2A, and GluN2B promoters, while knockdown of STAT1 by AAV-Cre in STAT1flox/flox mice or expressing dominant negative Y701F-STAT1 efficiently rescues hTau-induced suppression of NMDAR expression with amelioration of synaptic functions and memory performance. These findings indicate that hTau accumulation impairs synaptic plasticity through JAK2/STAT1-induced suppression of NMDAR expression, revealing a novel mechanism for hTau-associated synapse and memory deficits.

Wolbachia and Spiroplasma could influence bacterial communities of the spider mite Tetranychus truncatus.

The structures of arthropod bacterial communities are complex. These microbiotas usually provide many beneficial services to their hosts, whereas occasionally they may be parasitical. To date, little is known about the bacterial communities of Tetranychus truncatus and the factors contributing to the structure of its bacterial communities are unexplored yet. Here, we used four symbiont-infected T. truncatus strains-including one Wolbachia and Spiroplasma co-infected strain, two symbiont singly-infected strains and one symbiont uninfected strain-to investigate the influence of endosymbionts on the structure of the host mites' microbiota. Based on 16S rRNA genes sequencing analysis, we found Wolbachia and Spiroplasma were the two most abundant bacteria in T. truncatus and the presence of both symbionts could not change the diversity of bacterial communities (based on alpha-diversity indexes such as ACE, Chao1, Shannon and Simpson diversity index). Symbiont infection did alter the abundance of many other bacterial genera, such as Megamonas and Bacteroides. The structures of bacterial communities differed significantly among symbiont-infected strains. These results suggested a prominent effect of Wolbachia and Spiroplasma on bacterial communities of the host T. truncatus. These findings advance our understanding of T. truncatus microbiota and will be helpful for further study on bacterial communities of spider mites.

Comparative analysis of diet-associated responses in two rice planthopper species.

BACKGROUND: Host adaptation is the primary determinant of insect diversification. However, knowledge of different host ranges in closely related species remains scarce. The brown planthopper (Nilaparvata lugens, BPH) and the small brown planthopper (Laodelphax striatellus, SBPH) are the most destructive insect pests within the family Delphacidae. These two species differ in their host range (SBPH can well colonize rice and wheat plants, whereas BPH survives on only rice plants), but the underlying mechanism of this difference remains unknown. High-throughput sequencing provides a powerful approach for analyzing the association between changes in gene expression and the physiological responses of insects. Therefore, gut transcriptomes were performed to elucidate the genes associated with host adaptation in planthoppers. The comparative analysis of planthopper responses to different diets will improve our knowledge of host adaptation regarding herbivorous insects. RESULTS: In the present study, we analyzed the change in gene expression of SBPHs that were transferred from rice plants to wheat plants over the short term (rSBPH vs tSBPH) or were colonized on wheat plants over the long term (rSBPH vs wSBPH). The results showed that the majority of differentially expressed genes in SBPH showed similar changes in expression for short-term transfer and long-term colonization. Based on a comparative analysis of BPH and SBPH after transfer, the genes associated with sugar transporters and heat-shock proteins showed similar variation. However, most of the genes were differentially regulated between the two species. The detoxification-related genes were upregulated in SBPH after transfer from the rice plants to the wheat plants, but these genes were downregulated in BPH under the same conditions. In contrast, ribosomal-related genes were downregulated in SBPH after transfer, but these genes were upregulated in BPH under the same conditions. CONCLUSIONS: The results of this study provide evidence that host plants played a dominant role in shaping gene expression and that the low fitness of BPH on wheat plants might be determined within 24 h after transfer. This study deepens our understanding of different host ranges for the two planthopper species, which may provide a potential strategy for pest management.

Stable Establishment of Cardinium spp. in the Brown Planthopper Nilaparvata lugens despite Decreased Host Fitness.

The brown planthopper Nilaparvata lugens (Hemiptera) is a major pest of rice crops in Asia. Artificial transinfections of Wolbachia have recently been used for reducing host impacts, but transinfections have not yet been undertaken with another important endosymbiont, Cardinium This endosymbiont can manipulate the reproduction of hosts through phenotypes such as cytoplasmic incompatibility (CI), which is strong in the related white-backed planthopper, Sogatella furcifera (Hemiptera). Here, we stably infected N. lugens with Cardinium from S. furcifera and showed that it exhibits perfect maternal transmission in N. lugens The density of Cardinium varied across developmental stages and tissues of the transinfected host. Cardinium did not induce strong CI in N. lugens, likely due to its low density in testicles. The infection did decrease fecundity and hatching rate in the transinfected host, but a decrease in fecundity was not apparent when transinfected females mated with Wolbachia-infected males. The experiments show the feasibility of transferring Cardinium endosymbionts across hosts, but the deleterious effects of Cardinium on N. lugens limit its potential to spread in wild populations of N. lugens in the absence of strong CI.IMPORTANCE In this study we established a Cardinium-infected N. lugens line that possessed complete maternal transmission. Cardinium had a widespread distribution in tissues of N. lugens, and this infection decreased the fecundity and hatching rate of the host. Our findings emphasize the feasibility of transinfection of Cardinium in insects, which expands the range of endosymbionts that could be manipulated for pest control.

Wolbachia dominate Spiroplasma in the co-infected spider mite Tetranychus truncatus.

Wolbachia and Spiroplasma are both maternally inherited endosymbionts in arthropods, and they can co-infect the same species. However, how they interact with each other in the same host is not clear. Here we investigate a co-infected Tetranychus truncatus spider mite strain that shares the same genetic background with singly infected and uninfected strains to detect the impacts of the two symbionts on their host. We found that Wolbachia-infected and Spiroplasma-infected mites can suffer significant fitness costs involving decreased fecundity, although with no effect on lifespan or development. Wolbachia induced incomplete cytoplasmic incompatibility in T. truncatus both in singly infected and doubly infected strains, resulting in female killing. In both females and males of the co-infected spider mite strain, Wolbachia density was higher than Spiroplasma density. Transcriptome analysis of female adults showed that the most differentially expressed genes were found between the co-infected strain and both the singly infected Spiroplasma strain and uninfected strain. The Wolbachia strain had the fewest differentially expressed genes compared with the co-infected strain, consistent with the higher density of Wolbachia in the co-infected strain. Wolbachia, therefore, appears to have a competitive advantage in host mites over Spiroplasma and is likely maintained in populations by cytoplasmic incompatibility despite having deleterious fitness effects.

Geography alone cannot explain Tetranychus truncatus (Acari: Tetranychidae) population abundance and genetic diversity in the context of the center-periphery hypothesis.

The center-periphery hypothesis (CPH) states that the genetic diversity, genetic flow, and population abundance of a species are highest at the center of the species' geographic distribution. However, most CPH studies have focused on the geographic distance and have ignored ecological and historical effects. Studies using niche models to define the center and periphery of a distribution and the interactions among geographical, ecological, and historical gradients have rarely been done in the framework of the CPH, especially in biogeographical studies of animal species. Here, we examined the CPH for a widely distributed arthropod, Tetranychus truncatus (Acari: Tetranychidae), in eastern China using three measurements: geographic distance to the center of the distribution (geography), ecological suitability based on current climate data (ecology), and historical climate data from the last glacial maximum (history). We found that the relative abundances of different populations were more strongly related to ecology than to geography and history. Genetic diversity within populations and genetic differentiation among populations based on mitochondrial marker were only significantly related to history. However, the genetic diversity and population differentiation based on microsatellites were significantly related to all three CPH measurements. Overall, population abundance and genetic pattern cannot be explained very well by geography alone. Our results show that ecological gradients explain the variation in population abundance better than geographic gradients and historical factors, and that current and historical factors strongly influence the spatial patterns of genetic variation. This study highlights the importance of examining more than just geography when assessing the CPH.

Intraspecific mitochondrial genome comparison identified CYTB as a high-resolution population marker in a new pest Athetis lepigone.

A new outbreak pest, Athetis lepigone (Möschler) (Lepidoptera: Noctuidae), has caused severe economic loss in maize crops in China. In order to conduct population genetics study with a more polymorphic and scientific mitochondrial marker, we sequenced the complete mitochondrial genomes of 13 different A. lepigone individuals. Intraspecific comparison of all PCGs showed that the NADH dehydrogenase and cytochrome b genes had the highest nucleotide diversity. We also found evidence of episodic positive selection on two amino acids, which are encoded by NADH dehydrogenase genes (ND3 and ND4L), against a background of widespread neutral selection of all other mitochondrial PCGs. The genetic divergence observed in this study indicated that the cytochrome b gene (CYTB) is better than COI at recovering population structure. The preliminary population genetic analysis illustrated strong gene flow among A. lepigone populations in China. Our study provides basic information for further research on population genetics of A. lepigone.

Identification of Saliva Proteins of the Spider Mite Tetranychus evansi by Transcriptome and LC-MS/MS Analyses.

The spider mite Tetranychus evansi has a remarkable ability to suppress and manipulate plant defenses, which makes it an ideal model to investigate plant-herbivores interactions. In this study, a de novo assembly of the transcriptome of T. evansi is performed and the proteins in its secreted saliva by LC-MS/MS are characterized. A total of 29 365 unigenes are assembled and 136 saliva proteins are identified. Comparative analysis of the saliva proteins in T. evansi, T. truncatus, and T. urticae shows that 64 protein groups are shared by at least two Tetranychus species, and 52 protein groups are specifically identified in T. evansi. In addition, some saliva proteins are common in arthropod species, while others are species-specific. These results will help to elucidate the molecular mechanisms by which T. evansi modulates plant defenses.

Phylogenetic signals in pest abundance and distribution range of spider mites.

BACKGROUND: Attributes of pest species like host range are frequently reported as being evolutionarily constrained and showing phylogenetic signal. Because these attributes in turn could influence the abundance and impact of species, phylogenetic information could be useful in predicting the likely status of pests. In this study, we used regional (China) and global datasets to investigate phylogenetic patterns in occurrence patterns and host ranges of spider mites, which constitute a pest group of many cropping systems worldwide. RESULTS: We found significant phylogenetic signal in relative abundance and distribution range both at the regional and global scales. Relative abundance and range size of spider mites were positively correlated with host range, although these correlations became weaker after controlling for phylogeny. CONCLUSIONS: The results suggest that pest impacts are evolutionarily constrained. Information that is easily obtainable - including the number of known hosts and phylogenetic position of the mites - could therefore be useful in predicting future pest risk of species.