Behavioral Comparisons of Ingestion and Excretion by Selected Species of Pentatomids: Evidence of Feeding on Different Food Sources Supports Pest Status

Laboratory studies were conducted on food ingestion and excretion by selected species of pentatomids on different food sources to support their pest status. We compared the frequency and time of feeding on vegetative (stem) and reproductive (seed) structures of soybean, Glycine max (L.) Merrill and of maize, Zea mays L. by Piezodorus guildinii (Westwood), Dichelops melacanthus (Dallas), and Edessa meditabunda (F.); in addition, the amount of excreta (feces) produced were compared for D. melacanthus feeding on seed of soybean and stem of maize seedling. The feeding behavior of E. meditabunda and P. guildinii on soybean, and of D. melacanthus on maize was recorded using the electropenetrography (EPG) technique. Excretion was estimated using water sensitive paper recording number and area of fecal drops. Results indicated that E. meditabunda on soybean stem repeated events of ingestion (both xylem and phloem sap) over four times per bug during the 8 h of recording for ca. 53 min per event. Dichelops melacanthus on maize seedling repeated each ingestion event over three times per bug for ca. 24 min per event. Piezodorus guildinii feeding on soybean stem repeated each ingestion 1.2 times per bug for ca. 40 min per event; on seed endosperm, it fed for a longer time, ca. 80 min per event, each event repeated only 0.5 times per bug. Number of excretory drops was higher (9.9 drops per bug) when D. melacanthus fed on maize seedling than on soybean seed (1.4 drops per bug). A larger amount of saliva/regurgitate liquid food was expelled when bugs fed on the former than on the later food.     

Herbivore-induced infochemicals influence foraging behaviour in two intertidal predators

Herbivore-induced defences appear ubiquitous across most biomes and habitats. Yet the direct correlation between induced changes in host plant chemistry and the population dynamics of the herbivore remain untested in many systems. In plant–herbivore interactions in the terrestrial environment, indirect or tritrophic interactions appear a successful way in which changes in the host plant chemistry induced by prior herbivory can impact on herbivore populations via increased success of natural enemies. This set of interactions remains untested in the marine system. Here, we present work from experiments using orthogonal contrasts of plants with different prior treatments (control, mechanical damage or herbivory) and the presence or absence of herbivores on the foraging behaviour of a crab, Carcinus maenas, and a fish, Lipophrys pholis. These experiments were carried out using a novel flow-through flume, i.e. as a choice chamber supplied by turbulent water from independent cue sources. Our results show that in the Ascophyllum nodosum (plant)–Littorina obtusata (herbivore) system infochemicals from induced plants can directly influence predator foraging behaviour. L. pholis was attracted to the presence of a feeding L. obtusata, but was also more attracted to odours from herbivore-induced tissue than odours from mechanically damaged or naïve A. nodosum. C. maenas was more attracted to odours from herbivore-induced tissue compared to naïve tissue, regardless of the presence of L. obtusata. This is the first demonstration of such behavioural consequences of herbivore-induced changes in plants for marine systems.     

Feeding behaviors of rice-ear bugs, <Emphasis Type="Italic">Trigonotylus caelestialium</Emphasis> and <Emphasis Type="Italic">Stenotus rubrovittatus</Emphasis> (Hemiptera: Miridae), in response to starch and its related substances

We investigated the feeding behavior-stimulating properties of starch and related substances, namely, rice starch, soluble starch, amylopectin, and d-glucose, in the mirid bugs Trigonotylus caelestialium (Kirkaldy) and Stenotus rubrovittatus (Matsumura). Using an electrical penetration graph, feeding behaviors were roughly categorized into three distinct processes: test probing, ingestion, and resting. Rice starch strongly stimulated the feeding behavior of S. rubrovittatus at all concentrations tested (10–50%), prompting an increase in ingestion behavior and a decrease in resting behavior. Rice starch stimulated the feeding behavior of T. caelestialium at a concentration of 10%. Soluble starch also elicited feeding-stimulant activity in S. rubrovittatus at all concentrations tested (10–30%), but did not stimulate feeding behavior at any concentration tested in T. caelestialium. Amylopectin, a main component of rice starch, showed feeding-stimulant activity in S. rubrovittatus only at a concentration of 10%. In T. caelestialium, amylopectin did not stimulate ingestion, but did decrease resting behavior. d-Glucose, the building block of amylopectin, stimulated feeding behavior in S. rubrovittatus, leading to an increase in the duration and frequency of ingestion at concentrations of 10% and 10–20%, respectively. These findings indicate that starch is one of the main feeding stimulants for rice-ear bugs, particularly S. rubrovittatus.     

Comparative study of daytime and nighttime sap flow of <Emphasis Type="Italic">Populus euphratica</Emphasis>

In order to quantify and characterize the variance in desert riparian forest tree sap flow, we measured the sap flow from Populus euphratica and compared the daytime and nighttime patterns and responses to environmental variables. Results showed that daytime sap flow velocity was significantly higher (P?<?0.05). Daytime and nighttime mean sap flow velocities were 7.65 and 4.01 cm h^?1 in spring, 21.38 and 9.60 cm h^?1 in summer, and 11.04 and 5.21 cm h^?1 in autumn, respectively. Moreover, results indicated that the stoma remained partially open (15% minimum) throughout the night, providing sufficient evidence for the existance of nighttime transpiration. The vapor pressure deficit (VPD), stomatal conductance (Cs), photosynthetically active radiation (PAR), air temperature (Ta), wind speed (WS), and soil moisture (θ) all had significant positive effects on P. euphratica sap flow velocity (P?<?0.05). Furthermore, the relationship between daytime sap flow velocity and VPD showed clockwise hysteresis, while the relationship between nighttime sap flow velocity and VPD showed counter-clockwise hysteresis. It was evident that PAR and VPD were the key factors impacting daytime sap flow velocity, while Cs and θ were the key factors impacting nighttime sap flow velocity. Furthermore, linear regression results showed that daytime sap flow had a significant positive effect on nighttime sap flow throughout the growing season (P?<?0.05).     

Differences in Rice stripe virus transmission abilities of Laodelphax striatellus (Homoptera: Delphacidae) from four geographical populations

The small brown planthopper, Laodelphax striatellus (Fallén), can transfer Rice stripe virus (RSV) to host plants, which then develop rice stripe disease. Between vectors, there are two paths for RSV transmission. In current study, we examined the horizontal, vertical and compound transmission rates (horizontal and vertical transmissions together) by L. striatellus from one non-epidemic area (Fuyang in Zhejiang province) and three epidemic areas (Yizheng and Peixian in Jiangsu province, and Donggang in Liaoning province). RSV acquisition rates for naïve L. striatellus from the four populations were not significantly different. RSV transmission rate to healthy rice plants by viruliferous L. striatellus from Fuyang population was relatively lower than those of the other three populations. For example, RSV transmission rate in Fuyang population decreased by 1 fold compared to that in Peixian population when the transmission times were 48 and 72 h. It indicated that horizontal transmission ability of Fuyang population was lower. Vertical transmission rate and the compound transmission abilities of infective L. striatellus in the first generation did not differ significantly among the four populations. However, the ratio of RSV-positive offspring of an infective mother in the fourth generation of Fuyang population (84.3 ± 2.4%) was lowest, and decreased by 10% compared to that of Peixian population. It meant that compound transmission ability of Fuyang population was significantly lower than the other three populations. The reason for the difference in transmission abilities of L. striatellus from different populations was discussed.     

Does the Polyphagous Egg Parasitoid <Emphasis Type="Italic">Trichogramma platneri</Emphasis> Nagarkatti (Hymenoptera: Trichogrammatidae) Display Behavioral Plasticity When Parasitizing Different Hosts?

Trichogramma platneri oviposition behavior on Amorbia cuneana egg masses was investigated under laboratory conditions. No relationship was detected between host surface area, number of edge turning on host eggs, and parasitoid clutch size. It was also observed that females parasitized the egg mass randomly by drilling into the egg mass and parasitizing individual eggs without using stereotypical behaviors to assess individual hosts (i.e. drumming and turning). However, clutch size did change due to ovipositional experience as naïve wasps with little or no ovipositional experience (<6 eggs parasitized), allocated significantly more progeny per host than wasps with longer ovipositional experience (24-h oviposition experience on a single egg mass). Moreover, naïve wasps parasitized significantly more eggs on the outer edge of the egg mass than experienced wasps. We contend that the physical characteristics of A. cuneana eggs and egg masses preclude T. platneri from completely discriminating between individual eggs. However, because T. platneri may be using kairomones from the egg mass, this described oviposition strategy remains effective.     

An arthropod deterrent attracts specialised bees to their host plants

Many bee species are adapted to just a few specific plants in order to collect pollen (oligolecty). To reproduce successfully, it is important for oligolectic bees to find and recognise the specific host flowers. In this study, we investigated the role of floral volatiles used by an oligolectic bee to recognise its host plants. We compared the attractiveness of natural and synthetic scent samples of host flowers to foraging-naïve and -experienced Hoplitis adunca (Megachilidae) bees that are specialised on Echium and Pontechium (Boraginaceae) plants. The investigations showed that naïve H. adunca females are attracted to 1,4-benzoquinone. During their lifetime, bees learn additional floral cues while foraging on host flowers. In contrast to naïve ones, experienced H. adunca females use, in addition to 1,4-benzoquinone, other compounds to recognise their host plants. 1,4-Benzoquinone is an uncommon floral compound only known from the host plants of H. adunca, and is therefore ideally suited to be used as a plant-specific recognition cue. Several arthropods use this compound to deter insect predators. Therefore, 1,4-benzoquinone as an attractant in Echium flowers may have evolved from a primary function as a defensive compound against insect herbivores.     

Susceptibility of germinating cruciferous seeds to <Emphasis Type="Italic">Bagrada hilaris</Emphasis> (Hemiptera: Pentatomidae) feeding injury

Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) is a serious pest that attacks both germinating and seedling stages of a variety of cruciferous crops grown in the Central Coast of California. B. hilaris feeding on germinating seeds can cause severe stunting and plant mortality, and little is known about the feeding preference of B. hilaris for germinating seeds of major cruciferous hosts and varieties of hosts. No-choice and choice experiments were conducted in which germinating seeds in soilless and soil settings were exposed to B. hilaris adults for 7 days. Susceptibility scores were developed using B. hilaris feeding injury sites, distorted leaves, and deformed and dead plants to determine the overall B. hilaris preference for germinating host seeds. Based on the scores, the order of preference was arugula (Eruca sativa L.)?>?turnip (B. rapa L. var. rapa)?>?mizuna (B. rapa L. nipposinica)?>?kale (B. oleracea L. acephala)?>?choi (Brassica rapa L. var. chinensis)?>?broccoli (B. oleracea var. italica Plenck)?>?cauliflower (B. oleracea L. var. botrytis)?>?lettuce (Lactuca sativa L.)?>?sweet alyssum (Lobularia maritima [L.] Desv.). The lowest feeding injury was recorded on germinating lettuce and sweet alyssum seeds. Furthermore, no-choice and choice experiments were conducted with four varieties each of arugula and mizuna, twelve varieties each of kale and choi, and nine varieties/types of leafy Asian greens. The arugula varieties ‘Wild Rocket’ and ‘Spirit’ were more damaged by B. hilaris than other varieties tested. Among mizuna varieties, ‘Beira F1’ was more attractive to B. hilaris than ‘Scarlet’ or ‘Starbor F1.’ The choi varieties ‘Tokyo Bekana,’ ‘Feng Qing Choi F1,’ ‘Joi Choi F1,’ and ‘Win-Win Choi F1’ were more attractive than ‘Rosie F1.’ The leafy Asian greens variety ‘Carlton F1’ was more attractive to B. hilaris than ‘Yukina Savon,’ ‘Tatsoi OG,’ ‘Komatsuna Summerfest F1,’ ‘Red Rain F1,’ and ‘Shungiku.’ Therefore, the results suggest that not all varieties were equally susceptible to B. hilaris feeding and possibly be utilized for further field evaluation as a trap crop or developing more resistant varieties to B. hilaris.     

Metabolism or behavior: explaining the performance of aphids on alkaloid-producing fungal endophytes in annual ryegrass (<Emphasis Type="Italic">Lolium multiflorum</Emphasis>)

Plant–herbivore interactions are often mediated by plant microorganisms, and the “defensive mutualism” of epichloid fungal endophytes of grasses is an example. These endophytes synthesize bioactive alkaloids that generally have detrimental effects on the performance of insect herbivores, but the underlying mechanisms are not well understood. Our objective was to determine whether changes in the physiology and/or behavior of aphids explain the changes in performance of insects feeding on endophytic plants. We studied the interaction between the aphid Rhopalosiphum padi and the annual ryegrass Lolium multiflorum symbiotic (E+) or not symbiotic (E?) with the fungus Epichloë occultans that can synthesize loline alkaloids. We hypothesized that aphids feeding on E+ plants have higher energetic demands for detoxification of fungal alkaloids, thereby negatively impacting the individual performance, population growth, and structure. Aphids growing on E+ plants had lower values in morphometric and functional variables of individual performance, displayed lower birth rate, smaller population size, and dramatic structural changes. However, aphids exhibited lower values of standard metabolic rate (SMR) on E+ plants, which suggests no high costs of detoxification. Behavioral variables during the first 8 h of feeding showed that aphids did not change the phloem sap ingestion with the presence of fungal endophytes. We hypothesize that aphids may maintain phloem sap ingestion according to their fungal alkaloid tolerance capacity. In other words, when alkaloid concentrations overcome tolerance threshold, ingestion of phloem should decrease, which may explain the observed lower values of SMR in E+ feeding aphids.     

On distribution and ecology of some species of cleonines (Coleoptera,Curculionidae): IV. Genus <Emphasis Type="Italic">Lixus</Emphasis> F., subgenus <Emphasis Type="Italic">Eulixus</Emphasis> Reitt.

Data on habitats, food plants of larvae and adults, feeding, mating, oviposition, larval and pupal development, natural enemies, and distribution of seven weevil species (Lixus canescens F.-W., L. iridis Ol., L. myagri Ol., L. punctirostris Boh., L. subtilis Boh., L. incanescens Boh., and L. brevipes Bris.) are given. New host plants of L. canescens and L. iridis are revealed. Gall induction by L. brevipes is reported for the first time. Distribution of all the species in Ukraine and Russia (the latter based on the literature) are given in more detail. Information on the known and potential economic importance of every species is provided.     

Behavioral Plasticity in Probing by <Emphasis Type="Italic">Diaphorina citri</Emphasis> (Hemiptera,Liviidae): Ingestion from Phloem Versus Xylem is Influenced by Leaf Age and Surface

Diaphorina citri is a major pest of citrus because it transmits Candidatus Liberibacter asiaticus, a phloem-limited bacterium that putatively causes Huanglongbing (HLB). The disease moves slowly through a tree, and the vector facilitates further within-tree movement via transmission of the pathogen. However, this only happens when D. citri stylets contact the phloem, to inoculate bacteria during phloem salivation and acquire bacteria during phloem sap ingestion. Behavioral changes in D. citri associated with different plant parts would affect how long it takes to reach phloem and how long the psyllids stays in phloem to ingest, thereby influencing the risk of disease spread. D. citri feeding was recorded on the abaxial and adaxial surfaces of mature and immature citrus leaves. Adults in the field can be found on these surfaces at all times of year. On abaxial surface of immature leaves, phloem salivation would occur after 11 h on average, but rarely as soon as 0.56 h. The corresponding values on mature leaves were 16 and 2.7. In general, psyllids spent more time ingesting phloem sap on immature leaves than on mature leaves. Psyllids on abaxial surfaces spent more time ingesting from phloem, though the strength of this effect was less than for immature versus mature leaves. In contrast, xylem ingestion increased on mature leaves compared with young. The biological differences that could produce this outcome are discussed. The results discussed herein are of relevance to further studies on the efficacy of an insecticide to act quickly enough to prevent pathogen transmission.     

A PCR-based analysis of plant DNA reveals the feeding preferences of <Emphasis Type="Italic">Apolygus lucorum</Emphasis> (Heteroptera: Miridae)

The mirid bug Apolygus lucorum (Meyer-Dür) (Heteroptera: Miridae) is a severe pest of cotton and other crops in China. The feeding preferences of this pest are unclear due to its frequent movement among different host plants and the inconspicuous signs of its feeding. Here, we present results of a field trial that used direct observation of bug densities and a PCR-based molecular detection assay to detect plant DNA in bugs to explore relationships between A. lucorum population abundance and its feeding preference between two host plants, Humulus scandens (Loureiro) Merrill and Medicago sativa L. The field-plot samples showed that A. lucorum adults generally prefer flowering host plants. Its density was significantly higher on flowering H. scandens than on seedlings of M. sativa, and a similarly higher bug density was observed on flowering M. sativa than on seedlings of H. scandens. In the laboratory, we designed two pairs of species-specific primers targeting the trnL-F region for H. scandens and M. sativa, respectively. The detectability of plant DNA generally decreased with time post-feeding, and the half-life of plant DNA detection (DS₅₀) in the gut was estimated as 6.26 h for H. scandens and 3.79 h for M. sativa with significant differences between each other. In mirid bugs exposed to seedlings of H. scandens and flowering M. sativa, the detection rate of M. sativa DNA was significantly higher than that of H. scandens. Meanwhile, in mirid bugs exposed to seedlings of M. sativa and flowering H. scandens, a significantly higher detection rate of H. scandens DNA was found. We developed a useful tool to detect the remaining plant food species specifically from the gut of A. lucorum in the current study. We provided direct evidence of its feeding preference between H. scandens and M. sativa at different growth stages, which strongly supported a positive correlation between population abundance and feeding preference of A. lucorum on different plants under field conditions. The findings provide new insights into the understanding of A. lucorum’s feeding preference, and are helpful for developing the strategies to control this pest.     

The effect of galling aphids feeding on photosynthesis photochemistry of elm trees (<Emphasis Type="Italic">Ulmus</Emphasis> sp.)

Changes of chlorophyll (Chl) a fluorescence and photosynthetic pigment contents were analysed in galled leaves (visibly damaged and undamaged parts) and intact leaves. The values of minimal fluorescence of the dark-adapted state, maximal quantum yield of PSII photochemistry, effective quantum yield of PSII photochemical conversion, and photochemical quenching coefficient decreased in Ulmus pumila L. leaves galled by Tetraneura ulmi (L.) and in U. glabra Huds. galled by Eriosoma ulmi (L.). Colopha compressa (Koch.) feeding affected these parameters only in damaged parts of U. laevis Pall. galled leaves. The increasing number of T. ulmi galls progressively decreased photosynthetic performance. In gall tissues of all analysed aphid species, the lowest photosynthetic pigment content was found, indicating that the photosynthetic capacity must have been low in galls. Significant reduction of Chl and carotenoid contents were observed in damaged and undamaged portions of galled leaves only in the case of T. ulmi feeding.     

Quantifying Ostreid Herpesvirus (OsHV-1) Genome Copies and Expression during Transmission

Understanding the pathogenic potential of a new pathogen strain or a known pathogen in a new locale is crucial for management of disease in both wild and farmed animals. The Ostreid herpesvirus-1 (OsHV-1), a known pathogen of early-life-stage Pacific oysters, Crassostrea gigas, has been associated with mortalities of juvenile oysters in many locations around the world including Tomales Bay, California. In two trials, the California OsHV-1 strain was transmitted from infected juvenile C. gigas to naïve C. gigas larvae. Survival of control larvae was high throughout both trials (97–100%) and low among those exposed to OsHV-1. No OsHV-1-exposed larvae survived to day 9 in trial 1, while trial 2 was terminated at day 7 when survival was 36.90?±?8.66%. To assess the amount of OsHV-1 DNA present, we employed quantitative polymerase chain reaction (qPCR) assays based on the A fragment and OsHV-1 catalytic subunit of a DNA polymerase δ (DNA pol) gene. Viral genome copy numbers based on qPCR assays peaked between 3 and 5 days. To measure the presence of viable and actively transcribing virus, the DNA pol gene qPCR assay was optimized for RNA analysis after being reverse transcribed (RT-qPCR). A decline in virus gene expression was measured using RT-qPCR: relative to earlier experimental time points copy numbers were significantly lower on day 9, trial 1 (p?p?p?p?相似文献   

Strain-specific response to ampicillin in <Emphasis Type="Italic">Wolbachia-</Emphasis>infected mosquito cell lines

Wolbachia pipientis (Rickettsiales; Anaplasmataceae) is an obligate intracellular alpha proteobacterium that occurs in arthropods and filarial worms. Some strains of Wolbachia can be maintained as persistent infections in insect cell lines. C/wStr1 cells from the mosquito Aedes albopictus maintain a robust infection with Wolbachia strain wStr, originally isolated from the planthopper, Laodelphax striatellus. To explore possible functions of penicillin-binding proteins expressed from the wStr genome, C/wStr1 cells were exposed to ampicillin. Absolute levels of Wolbachia increased 3.5-fold in ampicillin-treated cells and fivefold in naive cells newly infected with wStr. Because cell numbers were depressed by ampicillin treatment, Wolbachia yield on a per-cell basis increased by 15-fold. The absence of a similar effect on wAlbB in Aa23 host cells suggests that the Wolbachia strain, the presence/absence of genes encoding penicillin-binding proteins, or the interaction between wAlbB and its host cells may modulate the effects of ampicillin.     

<Emphasis Type="Italic">m</Emphasis>-Trifluoromethyl-diphenyl Diselenide Regulates Prefrontal Cortical MOR and KOR Protein Levels and Abolishes the Phenotype Induced by Repeated Forced Swim Stress in Mice

The present study aimed to investigate the m-trifluoromethyl-diphenyl diselenide [(m-CF₃-PhSe)₂] effects on prefrontal cortical MOR and KOR protein levels and phenotype induced by repeated forced swim stress (FSS) in mice. Adult Swiss mice were subjected to repeated FSS sessions, and after that, they performed the spontaneous locomotor/exploratory activity, tail suspension, and splash tests. (m-CF₃-PhSe)₂ (0.1 to 5 mg/kg) was administered to mice 30 min before the first FSS session and 30 min before the subsequent repeated FSS. (m-CF₃-PhSe)₂ abolished the phenotype induced by repeated FSS in mice. In addition, a single FSS session increased μ but reduced δ-opioid receptor contents, without changing the κ content. Mice subjected to repeated FSS had an increase in the μ content when compared to those of naïve group or subjected to single FSS. Repeated FSS induced an increase of δ-opioid receptor content compared to those mice subjected to single FSS. However, the δ-opioid receptor contents were lower than those found in the naïve group. The mice subjected to repeated FSS showed an increase in the κ-opioid receptor content when compared to that of the naïve mice. (m-CF₃-PhSe)₂ regulated the protein contents of μ and κ receptors in mice subjected to repeated FSS. These findings demonstrate that (m-CF₃-PhSe)₂ was effective to abolish the phenotype induced by FSS, which was accompanied by changes in the contents of cortical μ- and κ-opioid receptors.     

Population Diversity of Rice Stripe Virus-Derived siRNAs in Three Different Hosts and RNAi-Based Antiviral Immunity in Laodelphgax striatellus

Background

Small RNA-mediated gene silencing plays evolutionarily conserved roles in gene regulation and defense against invasive nucleic acids. Virus-derived small interfering RNAs (vsiRNAs) are one of the key elements involved in RNA silencing-based antiviral activities in plant and insect. vsiRNAs produced after viruses infecting hosts from a single kingdom (i.e., plant or animal) are well described. In contrast, vsiRNAs derived from viruses capable of infecting both plants and their insect vectors have not been characterized.

Methodology/Principal Findings

We examined Rice stripe virus (RSV)-derived small interfering RNAs in three different hosts, Oryza sativa, Nicotiana benthamiana and a natural RSV transmitting vector Laodelphgax striatellus, through deep sequencing. Our results show that large amounts of vsiRNAs generated in these hosts after RSV infection. The vsiRNAs from N. benthamiana and L. striatellus mapped equally to the genomic- and antigenomic-strand of RSV RNAs. They showed, however, a significant bias in those from O. sativa. Furthermore, our results demonstrate that the number and size distributions of vsiRNAs in the three hosts were very different. In O. sativa and N. benthamiana, most vsiRNAs were mapped to the discrete regions in the RSV genome sequence, and most of the vsiRNAs from these two hosts were generated from RSV genomic RNAs 3 and 4. In contrast, the vsiRNAs identified in L. striatellus distributed uniformly along the whole genome of RSV. We have also shown that silencing Agronaute 2 in L. striatellus enhanced RSV accumulation in this host.

Conclusions/Significance

Our study demonstrates that the core RNA-induced gene silencing (RNAi) machinery is present in L. striatellus. We also provide evidence that the RNAi-mediated immunity against RSV is present in L. striatellus. We propose that a common small RNA-mediated virus defense mechanism exists in both helipterum insects and plants, but the vsiRNAs are generated differentially in different hosts.