Correction to: The nucleocapsid protein of rice stripe virus in cell nuclei of vector insect regulates viral replication

In the original publication of the article Fig. 3A and Fig. 33B were incorrectly published. The correct figures are available in this correction.

Interplay of Rice Stripe Virus and Rice Black Streaked Dwarf Virus during Their Acquisition and Accumulation in Insect Vector

Plant viruses transmitted by hemipteran vectors commonly cause losses to crop production. Rice stripe virus (RSV) and rice black streaked dwarf virus (RBSDV) are transmitted to rice plants by the same vector, the small brown planthopper (SBPH), Laodelphax striatellus Fallén, in a persistent propagative manner. However, rarely do the respective diseases they cause occur simultaneously in a field. Here, we determined the acquisition efficiency of RSV and RBSDV when acquired in succession or simultaneously by SBPH. When RBSDV was acquired first, RSV acquisition efficiency was significantly lower than when only acquiring RSV. However, RBSDV acquisition efficiency from insects that acquired RSV first was not significantly different between the insects only acquiring RBSDV. Immunofluorescence assays showed that the acquisition of RBSDV first might inhibit RSV entry into midgut epithelial cells, but RSV did not affect RBSDV entry. SBPHs were more likely to acquire RBSDV when they were feeding on plants coinfected with the two viruses. When RBSDV was acquired before RSV, RBSDV titer was significantly higher and RSV titer first declined, then increased compared to when only acquiring RBSDV or RSV. Only 5% of the SBPHs acquired both viruses when feeding on plants coinfected with RSV and RBSDV. These results provide a better understanding of the interaction between two persistent viruses when present in the same vector insect and explain why RSV and RBSDV occur in intermittent epidemics.

Larvicidal Activity of Essential Oils From Piper Species Against Strains of Aedes aegypti (Diptera: Culicidae) Resistant to Pyrethroids

The continuous and indiscriminate use of insecticides has been responsible for the emergence of insecticide resistant vector insect populations, especially in Aedes aegypti. Thus, it is urgent to find natural insecticide compounds with novel mode of action for vector control. The goal of this study was to investigate the larvicidal activity of essential oils (EOs) from Piper species against A. aegypti characterized as resistant and susceptible strains to pyrethroids. The EOs from leaves of 10 Piper species were submitted to the evaluation of larvicidal activity in populations of A. aegypti in agreement with the (World Health Organization, 2005) guidelines. The resistance of the strains characterized by determining the lethal concentrations (LCs) with the insecticide deltamethrin (positive control). The major compounds of the EOs from Piper species was identified by GC-MS. The EOs from Piper aduncum, P. marginatum, P. gaudichaudianum, P. crassinervium, and P. arboreum showed activity of up to 90% lethality at 100 ppm (concentration for screening). The activities of the EOs from these 6 species showed similar LCs in both susceptible strain (Rockefeller) and resistant strains (Pampulha and Venda Nova) to pyrethroids. The major compounds identified in the most active EO were available commercially and included β-Asarone, (E)-Anethole, (E)-β-Caryophyllene, γ-Terpinene, p-Cymene, Limonene, α-Pinene, and β-Pinene. Dillapiole was purified by from EO of P. aduncum. The phenylpropanoids [Dillapiole, (E)-Anethole and β-Asarone] and monoterpenes (γ-Terpinene, p-Cymene, Limonene, α-Pinene, and β-Pinene) showed larvicidal activity with mortality between 90 and 100% and could account for the toxicity of these EOs, but the sesquiterpene (E)-β-Caryophyllene, an abundant component in the EOs of P. hemmendorffii and P. crassinervium, did not show activity on the three populations of A. aegypti larvae at a concentration of 100 ppm. These results indicate that Piper's EOs should be further evaluated as a potential larvicide, against strains resistant to currently used pesticides, and the identification of phenylpropanoids and monoterpenes as the active compounds open the possibility to study their mechanism of action.

The nucleocapsid protein of rice stripe virus in cell nuclei of vector insect regulates viral replication

Rice stripe virus (RSV) transmitted by the small brown planthopper causes severe rice yield losses in Asian countries. Although viral nuclear entry promotes viral replication in host cells, whether this phenomenon occurs in vector cells remains unknown. Therefore, in this study, we systematically evaluated the presence and roles of RSV in the nuclei of vector insect cells. We observed that the nucleocapsid protein (NP) and viral genomic RNAs were partially transported into vector cell nuclei by utilizing the importin α nuclear transport system. When blocking NP nuclear localization, cytoplasmic RSV accumulation significantly increased. In the vector cell nuclei, NP bound the transcription factor YY1 and affected its positive regulation to FAIM. Subsequently, decreased FAIM expression triggered an antiviral caspase-dependent apoptotic reaction. Our results reveal that viral nuclear entry induces completely different immune effects in vector and host cells, providing new insights into the balance between viral load and the immunity pressure in vector insects.

Insights Into Insect Vector Transmission and Epidemiology of Plant-Infecting Fijiviruses

Viruses in genus Fijivirus (family Reoviridae) have caused serious damage to rice, maize and sugarcane in American, Asian, European and Oceanian countries, where seven plant-infecting and two insect-specific viruses have been reported. Because the planthopper vectors are the only means of virus spread in nature, their migration and efficient transmission of these viruses among different crops or gramineous weeds in a persistent propagative manner are obligatory for virus epidemics. Understanding the mechanisms of virus transmission by these insect vectors is thus key for managing the spread of virus. This review describes current understandings of main fijiviruses and their insect vectors, transmission characteristics, effects of viruses on the behavior and physiology of vector insects, molecular transmission mechanisms. The relationships among transmission, virus epidemics and management are also discussed. To better understand fijivirus-plant disease system, research needs to focus on the complex interactions among the virus, insect vector, insect microbes, and plants.

Reemerging Rice Orange Leaf Phytoplasma with Varying Symptoms Expressions and Its Transmission by a New Leafhopper Vector—Nephotettix virescens Distant

Rice orange leaf phytoplasma (ROLP) belongs to the “Candidatus Phytoplasma asteris” 16SrI-B subgroup, which is solely transmitted by the zigzag-striped leafhopper (Recilia dorsalis Motchulsky) and the green leafhopper (Nephotettix cincticeps Uhler) (Hemiptera: Cicadellidae). Recently, rice plants showing orange leaf discoloration have become ubiquitous in several paddies of two provinces in the Philippines. In total of 98 symptomatic rice plants, 82% (Laguna) and 95% (Mindanao) were ROLP-positive by nested PCR detection. These plants showed more varying symptoms than previously reported. The vector insect R. dorsalis was scarcely present but green paddy leafhopper, N. virescens Distant (Hemiptera: Cicadellidae), was commonly observed in the paddies, thus the ability of N. virescens to transmit ROLP was thoroughly investigated. Newly emerged adult N. virescens, which fed on ROLD-source rice plants, were used to inoculate a susceptible rice seedling and was serially transferred into a new healthy seedling. Resultant positive transmission rates varied from 5.1% to 17.8%. The transmission ability of the insects was generally decreased over time. These findings suggest that N. virescens is an alternative vector of ROLP in the Philippines. Altogether, this study highlighted the increasing importance of ROLD-reemergence in Southeast and East Asia and proved the need for careful management of this alternative vector insect.

Seroprevalence of Chagas disease in Southern Brazilian cardiac patients and their knowledge about the parasitosis and vectors

Chagas disease (CD) is considered a typical low-income population sickness of the developing countries in Latin America. Given the historical relevance of CD in individuals in southern Rio Grande do Sul (RS) State, Brazil, the aim of this study was to identify the knowledge of the CD and its vectors by cardiac patients, and the prevalence of anti-T cruzi antibodies in these individuals in Pelotas, city located in Rio Grande do Sul (RS) state, Brazil. The subjects with cardiac disease were submitted to a semi-structured questionnaire as well as two serological tests in order to detect anti-T. cruzi IgG antibodies. Of the individuals that born in municipalities showing the highest triatomine infestation rates in recent decades, 81.8% were able to recognize the vector insect (p = 0.0042; OR = 5.9), and 83.3% reported either themselves or someone in their families to have CD (p = 0.043, OR = 5.2). Of the 54 patients submitted to serological analysis, only 01 patient (1.9%) was positive for anti-T. cruzi antibodies, a 55 year old man from the rural area of Canguçu county. This study provides support for the evaluation to be extended to other cardiology centers, given the importance of Chagas disease in Brazil.