Aranzazu Moreno - Academia.edu (original) (raw)

Papers by Aranzazu Moreno

Advances in Virus Research, 2012

Virus Research Issn 0168 1702 2014 06 Vol 186 N, Jun 1, 2014

Please cite this article in press as: Carmo-Sousa, M., et al., A non-persistently transmitted-vir... more Please cite this article in press as: Carmo-Sousa, M., et al., A non-persistently transmitted-virus induces a pull-push strategy in its aphid vector to optimize transmission and spread. Virus Res. (2014), http://dx.a b s t r a c t Plant viruses are known to modify the behaviour of their insect vectors, both directly and indirectly, generally adapting to each type of virus-vector relationship in a way that enhances transmission efficiency. Here, we report results of three different studies showing how a virus transmitted in a nonpersistent (NP) manner (Cucumber mosaic virus; CMV, Cucumovirus) can induce changes in its host plant, cucumber (Cucumis sativus cv. Marumba) that modifies the behaviour of its aphid vector (Aphis gossypii Glover; Hemiptera: Aphididae) in a way that enhances virus transmission and spread non-viruliferous aphids changed their alighting, settling and probing behaviour activities over time when exposed to CMV-infected and mock-inoculated cucumber plants. Aphids exhibited no preference to migrate from CMV-infected to mock-inoculated plants at short time intervals (1, 10 and 30 min after release), but showed a clear shift in preference to migrate from CMV-infected to mock-inoculated plants 60 min after release. Our free-choice preference assays showed that A. gossypii alates preferred CMV-infected over mock-inoculated plants at an early stage (30 min), but this behaviour was reverted at a later stage and aphids preferred to settle and reproduce on mock-inoculated plants. The electrical penetration graph (EPG) technique revealed a sharp change in aphid probing behaviour over time when exposed to CMVinfected plants. At the beginning (first 15 min) aphid vectors dramatically increased the number of short superficial probes and intracellular punctures when exposed to CMV-infected plants. At a later stage (second hour of recording) aphids diminished their feeding on CMV-infected plants as indicated by much less time spent in phloem salivation and ingestion (E1 and E2). This particular probing behaviour including an early increase in the number of short superficial probes and intracellular punctures followed by a phloem feeding deterrence is known to enhance the transmission efficiency of viruses transmitted in a NP manner. We conclude that CMV induces specific changes in a plant host that modify the alighting, settling and probing behaviour of its main vector A. gossypii, leading to optimum transmission and spread of the virus. Our findings should be considered when modelling the spread of viruses transmitted in a NP manner.

Neotropical Entomology, 2014

ABSTRACT Plant viruses can directly influence their insect vectors, and indirectly through their ... more ABSTRACT Plant viruses can directly influence their insect vectors, and indirectly through their shared host plant, altering their behavior and performance in a mutualistic or rather antagonistic manner. One of the most studied begomovirus, Tomato yellow leaf curl virus (TYLCV), may also facilitate the expansion of its vector, the whitefly Bemisia tabaci (Gennadius). Considering the likely expansion of the disease and its major vector, we studied the direct and the indirect effects of a Mediterranean isolate of this virus (TYLCV-IL) on the biological performance of the Q biotype of B. tabaci. The following parameters were examined: development time and viability of nymphs, sex ratio, fecundity, and fertility and longevity. The results varied from positive to neutral depending on the parameter and the effect studied. TYLCV accelerated nymphal developmental and increased male longevity of B. tabaci when viruliferous insects developed on TYLCV-immune eggplants (direct effects). An indirect, positive effect of TYLCV-infected plants was observed on fecundity of B. tabaci, which laid more eggs on virus-infected than on noninfected tomato plants. Our results show that TYLCV enhances the population increase of its whitefly vector and that there is a high risk of rapid expansion of both the virus and its vector—the MED species of B. tabaci—into new areas when both agents interact together.

Ann Entomol Soc Amer, 2005

Caulißower mosaic virus (CaMV) is transmitted to crucifers in a noncirculative manner by several ... more Caulißower mosaic virus (CaMV) is transmitted to crucifers in a noncirculative manner by several aphid species. CaMV is preferentially acquired from the phloem, although acquisition also occurs after brief intracellular stylet punctures of aphid vectors in nonvascular leaf tissues. In the present work, we used the electrical penetration graph technique to study the speciÞc aphid stylet activities and behavioral events leading to the inoculation of CaMV to turnip plants by its two major vectors, Brevicoryne brassicae (L.) and Myzus persicae (Sulzer). Aphids subjected to an 8-h acquisition access time on infected plants were transferred to test plants and removed immediately after speciÞc behavioral events were recorded. CaMV was readily inoculated after the Þrst intracellular puncture in nonvascular tissues by both vector species. Inoculation rate of CaMV by B. brassicae was the highest after a 3-h inoculation access period, regardless of whether aphids had reached the phloem phase during that period. Consistent interspeciÞc differences also were found in the ability of both aphid vectors to retain CaMV. B. brassicae could retain the virus after several intracellular punctures, whereas M. persicae readily lost the virus after performing the same number of intracellular stylet punctures. We concluded that salivation by aphids during successive intracellular stylet punctures in the epidermal and mesophyll cells before reaching the phloem phase are the key behavioral events associated to the inoculation of Caulißower mosaic virus. The likely location of the viral retention site inside the aphid mouthparts is discussed.

As technology and transportation create a global community, researchers are increasingly aware of... more As technology and transportation create a global community, researchers are increasingly aware of the need to address widespread crop production challenges using an international perspective. Specific diseases and pests have become universal problems. Potato virus Y (PVY), which is vectored by aphids, has persisted as a problematic disease in potatoes and related crops worldwide. Though the virus is well established in many countries, there have been shifts in the strains dominating each region. For example, the strains present in the United States have shifted from PVYO to PVYNO or PVYNTN. In contrast, in Europe, PVYN is already dominant. Multiple alternative weed hosts have been identified in Europe, which may have contributed to strain dominance. In an effort to understand shifts in strains, a collaborative effort was made to: 1) investigate PVY transmission between known weed hosts and potatoes, and 2) assess vector preferences for healthy or infected plants. Major aphid vectors...

Advances in virus research, 2012

Lettuce is frequently attacked by several viruses causing disease epidemics and considerable yiel... more Lettuce is frequently attacked by several viruses causing disease epidemics and considerable yield losses along the Mediterranean basin. Aphids are key pests and the major vectors of plant viruses in lettuce fields. Lettuce mosaic virus (LMV) is probably the most important because it is seed-transmitted in addition to be transmissible by many aphid species that alight on the crop. Tomato spotted wilt virus (TSWV) is another virus that causes severe damage since the introduction of its major vector, the thrips Frankliniella occidentalis. In regions with heavy and humid soils, Lettuce Mirafiori big-vein virus (LMBVV) can also produce major yield losses.

Spanish Journal of Agricultural Research, 2007

Lettuce mosaic virus (LMV) is transmitted by aphids nonpersistently causing severe disease outbre... more Lettuce mosaic virus (LMV) is transmitted by aphids nonpersistently causing severe disease outbreaks in commercial lettuce crops. New strategies to control plant viruses have arisen based on molecular techniques, which analyze plantvirus-vector interactions. In this work, two PCR-based methods with a previous immunocapture phase, have been developed to detect LMV in single aphids. Detection rates using a RT-nested-PCR method in single aphids and transmission efficiency of Myzus persicae (vector species) and Nasonovia ribisnigri (nonvector species) were compared. Although the percentage of viruliferous aphids for N. ribisnigri (45.8 ± 2.3) was higher than for M. persicae (39.2 ± 3.5) after the same acquisition access period, N. ribisnigri was unable to transmit the virus while M. persicae proved to be an efficient vector (with a transmission rate per single aphid of 10.4 ± 0.8). A method was proposed to estimate vector propensity for nonpersistent viruses based on the relationship between the percentage of viruliferous aphids and their transmission ability. This methodology could be applied to decision-making and implementing control strategies to prevent virus spreading.

Virus Research, 2014

Please cite this article in press as: Carmo-Sousa, M., et al., A non-persistently transmitted-vir... more Please cite this article in press as: Carmo-Sousa, M., et al., A non-persistently transmitted-virus induces a pull-push strategy in its aphid vector to optimize transmission and spread. Virus Res. (2014), http://dx.a b s t r a c t Plant viruses are known to modify the behaviour of their insect vectors, both directly and indirectly, generally adapting to each type of virus-vector relationship in a way that enhances transmission efficiency. Here, we report results of three different studies showing how a virus transmitted in a nonpersistent (NP) manner (Cucumber mosaic virus; CMV, Cucumovirus) can induce changes in its host plant, cucumber (Cucumis sativus cv. Marumba) that modifies the behaviour of its aphid vector (Aphis gossypii Glover; Hemiptera: Aphididae) in a way that enhances virus transmission and spread non-viruliferous aphids changed their alighting, settling and probing behaviour activities over time when exposed to CMV-infected and mock-inoculated cucumber plants. Aphids exhibited no preference to migrate from CMV-infected to mock-inoculated plants at short time intervals (1, 10 and 30 min after release), but showed a clear shift in preference to migrate from CMV-infected to mock-inoculated plants 60 min after release. Our free-choice preference assays showed that A. gossypii alates preferred CMV-infected over mock-inoculated plants at an early stage (30 min), but this behaviour was reverted at a later stage and aphids preferred to settle and reproduce on mock-inoculated plants. The electrical penetration graph (EPG) technique revealed a sharp change in aphid probing behaviour over time when exposed to CMVinfected plants. At the beginning (first 15 min) aphid vectors dramatically increased the number of short superficial probes and intracellular punctures when exposed to CMV-infected plants. At a later stage (second hour of recording) aphids diminished their feeding on CMV-infected plants as indicated by much less time spent in phloem salivation and ingestion (E1 and E2). This particular probing behaviour including an early increase in the number of short superficial probes and intracellular punctures followed by a phloem feeding deterrence is known to enhance the transmission efficiency of viruses transmitted in a NP manner. We conclude that CMV induces specific changes in a plant host that modify the alighting, settling and probing behaviour of its main vector A. gossypii, leading to optimum transmission and spread of the virus. Our findings should be considered when modelling the spread of viruses transmitted in a NP manner.

Phytopathology, 2012

Vidal, E., Yokomi, R. K., Moreno, A., Bertolini, E., and Cambra, M. 2012. Calculation of diagnost... more Vidal, E., Yokomi, R. K., Moreno, A., Bertolini, E., and Cambra, M. 2012. Calculation of diagnostic parameters of advanced serological and molecular tissue-print methods for detection of Citrus tristeza virus: A model for other plant pathogens. Phytopathology 102:114-121.

Virus Research, 2009

Homopterans including aphids, whiteflies and leafhoppers are the major vectors of viruses compris... more Homopterans including aphids, whiteflies and leafhoppers are the major vectors of viruses comprising more than 80% of insect-transmitted viruses which represents close to 400 virus species within 39 different genera. Host plant recognition by homopterans requires a series of steps that are linked to plant virus transmission, including host searching or pre-alighting behaviour, probing on superficial tissues, settlement and stylet penetration to the target feeding tissues and salivation and continuous sap ingestion from the preferred feeding site. This review considers how vector behaviour influences the transmission and spread of plant viruses depending on the type of virus-vector relationship. Most studies have concentrated on aphid-transmitted viruses and particular probing and feeding behavioural processes and activities leading to the transmission of cuticula-borne and circulative viruses have been identified. The review also focuses on which are the most likely retention sites within the insect's body of cuticula-borne viruses. Finally, the influences of virus infection on vector behaviour such as changes in the attractiveness, settlement or feeding preference together with changes on vector performance (development, fecundity, rate of population increase and survival) are discussed.

Plant Pathology, 2012

The control of Plum pox virus (PPV), the most important viral disease that affects stone fruit tr... more The control of Plum pox virus (PPV), the most important viral disease that affects stone fruit trees, requires the use of reliable detection methods. The effectiveness of spot real-time reverse transcriptase polymerase chain reaction (RT-PCR) for the detection of PPV in samples collected from nursery blocks was compared with a validated PPV detection technique, the double antibody sandwich indirect enzyme-linked immunosorbent assay (DASI-ELISA) using the PPV-specific monoclonal antibody 5B-IVIA ⁄ AMR. In total, 5047 nursery plants were analysed by both techniques. The agreement between the techniques was almost perfect (Cohen's kappa index of 0AE88 ± 0AE01). The diagnostic parameters (sensitivity, specificity and likelihood ratios) of both techniques were simultaneously evaluated in 2473 nursery plants by latent class models using maximum likelihood functions and a Bayesian approach. The sensitivity and specificity of both techniques did not vary according to the latent model applied. Spot real-time RT-PCR was more sensitive while DASI-ELISA was more specific for PPV detection. In addition, the findings demonstrate that latent class models are a flexible and potent statistical method to estimate the accuracy of diagnostic tests for plant pathology.

Journal of Virology, 2005

Viruses frequently use insect vectors to effect rapid spread through host populations. In plant v... more Viruses frequently use insect vectors to effect rapid spread through host populations. In plant viruses, vector transmission is the major mode of transmission, used by nearly 80% of species described to date. Despite the importance of this phenomenon in epidemiology, the specificity of the virus-vector relationship is poorly understood at both the molecular and the evolutionary level, and very limited data are available on the precise viral protein motifs that control specificity. Here, using the aphid-transmitted Cauliflower mosaic virus (CaMV) as a biological model, we confirm that the "noncirculative" mode of transmission dominant in plant viruses (designated "mechanical vector transmission" in animal viruses) involves extremely specific virus-vector recognition, and we identify an amino acid position in the "helper component" (HC) protein of CaMV involved in such recognition. Site-directed mutagenesis revealed that changing the residue at this position can differentially affect transmission rates obtained with various aphid species, thus modifying the spectrum of vector species for CaMV. Most interestingly, in a virus line transmitted by a single vector species, we observed the rapid appearance of a spontaneous mutant specifically losing its transmissibility by another aphid species. Hence, in addition to the first identification of an HC motif directly involved in specific vector recognition, we demonstrate that change of a virus to a different vector species requires only a single mutation and can occur rapidly and spontaneously.

Journal of General Virology, 2012

Inoculation of the semi-persistent cauliflower mosaic virus (CaMV, genus Caulimovirus) is associa... more Inoculation of the semi-persistent cauliflower mosaic virus (CaMV, genus Caulimovirus) is associated with successive brief (5-10 s) intracellular stylet punctures (pd) when aphids probe in epidermal and mesophyll cells. In contrast to non-persistent viruses, there is no evidence for which of the pd subphases (II-1, II-2 and II-3) is involved in the inoculation of CaMV. Experiments were conducted using the electrical penetration graph (EPG) technique to investigate what particular subphases of the pd are associated with the inoculation of CaMV to turnip by its aphid vector Brevicoryne brassicae. In addition, the same aphid species/test plant combination was used to compare the role of the pd subphases in the inoculation of the non-persistent turnip mosaic virus (TuMV, genus Potyvirus). Inoculation of TuMV was found to be related to subphase II-1, confirming earlier results, but CaMV inoculation appeared to be related exclusively to subphase II-2 instead. The mechanism of CaMV inoculation and the possible nature of subphase II-2 are discussed in the scope of our findings. %paper no. vir037887 charlesworth ref: vir037887& Plant

Entomologia Experimentalis et Applicata, 2014

ABSTRACT The tomato potato psyllid (TPP), Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), i... more ABSTRACT The tomato potato psyllid (TPP), Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is the main vector of the bacterium Candidatus Liberibacter solanacearum (Lso), a major disease of solanaceous crops. Feeding of TPP is associated with Lso transmission. However, very little is known about the stylet penetration activities linked to acquisition and inoculation of Lso. The electrical penetration graph (EPG)-DC system was used to monitor stylet penetration activities during acquisition and inoculation of Lso by individual TPP on tomato [Solanum lycopersicum L. (Solanaceae)]. Female TPP from Lso-free and Lso-infected colonies were used in acquisition and inoculation tests, respectively. In the acquisition tests, TPP were tested for Lso after EPG recording of their stylet penetration activities on Lso-infected tomato shoots. In the inoculation tests, samples from the tomato plants on which the stylet penetration of Lso-infected TPP had been recorded were tested for Lso infection. The relationships between qPCR results and the EPG waveforms (C, G, D, E1, and E2) representing the main stylet penetration activities performed by individual insects in inoculation and acquisition tests were investigated. Results confirmed that a single adult TPP is capable of infecting a plant with Lso. Our data suggest that acquisition of the bacteria occurs during phloem ingestion (E2), and inoculation is likely associated with salivation into the phloem sieve elements (E1). The durations of EPG parameters were not significantly different between Lso-infected and Lso-free TPP (later shown by qPCR) in acquisition tests. In inoculation tests, the durations of E1 or E2 recorded from TPP on Lso-infected and Lso-free plants that were later shown by qPCR were not significantly different. However, C was shorter on Lso-infected plants than on Lso-free plants, where TPP performed phloem activities. The minimum plant access period required for Lso transmission by a single TPP was estimated to be ca. 2 h, with an acquisition threshold of about 36 min.

Archives of Virology, 2009

The viral charge acquired and inoculated by single aphids in a non-circulative transmission is es... more The viral charge acquired and inoculated by single aphids in a non-circulative transmission is estimated using plum pox virus (PPV). A combination of electrical penetration graph and TaqMan real-time RT-PCR techniques was used to establish the average number of PPV RNA targets inoculated by an aphid in a single probe (26,750), approximately half of the acquired ones. This number of PPV targets is responsible for a systemic infection of 20% on the inoculated receptor plants. No significant differences were found between the number of PPV RNA targets acquired after one and after five intracellular punctures (pd), but the frequency of infected receptor plants was higher after 5 pd. The percentage of PPV-positive leaf discs after just 1 pd of inoculation probe (28%/4,603 targets) was lower than after 5 pd (45.8%/135 9 10 6 targets). The methodology employed could be easily extended to other virus-vector-host combinations to improve the accuracy of models used in virus epidemiology.

Annals of the Entomological Society of America, 2005

Caulißower mosaic virus (CaMV) is transmitted to crucifers in a noncirculative manner by several ... more Caulißower mosaic virus (CaMV) is transmitted to crucifers in a noncirculative manner by several aphid species. CaMV is preferentially acquired from the phloem, although acquisition also occurs after brief intracellular stylet punctures of aphid vectors in nonvascular leaf tissues. In the present work, we used the electrical penetration graph technique to study the speciÞc aphid stylet activities and behavioral events leading to the inoculation of CaMV to turnip plants by its two major vectors, Brevicoryne brassicae (L.) and Myzus persicae (Sulzer). Aphids subjected to an 8-h acquisition access time on infected plants were transferred to test plants and removed immediately after speciÞc behavioral events were recorded. CaMV was readily inoculated after the Þrst intracellular puncture in nonvascular tissues by both vector species. Inoculation rate of CaMV by B. brassicae was the highest after a 3-h inoculation access period, regardless of whether aphids had reached the phloem phase during that period. Consistent interspeciÞc differences also were found in the ability of both aphid vectors to retain CaMV. B. brassicae could retain the virus after several intracellular punctures, whereas M. persicae readily lost the virus after performing the same number of intracellular stylet punctures. We concluded that salivation by aphids during successive intracellular stylet punctures in the epidermal and mesophyll cells before reaching the phloem phase are the key behavioral events associated to the inoculation of Caulißower mosaic virus. The likely location of the viral retention site inside the aphid mouthparts is discussed.

Scientific Reports, 2016

Increasing atmospheric carbon dioxide (CO2) impacts plant growth and metabolism. Indirectly, the ... more Increasing atmospheric carbon dioxide (CO2) impacts plant growth and metabolism. Indirectly, the performance and feeding of insects is affected by plant nutritional quality and resistance traits. Life history and feeding behaviour of Myzus persicae were studied on pepper plants under ambient (aCO2, 400 ppm) or elevated CO2 (eCO2, 650 ppm), as well as the direct impact on plant growth and leaf chemistry. Plant parameters were significantly altered by eCO2 with a negative impact on aphid's life history. Their pre-reproductive period was 11% longer and fecundity decreased by 37%. Peppers fixed significantly less nitrogen, which explains the poor aphid performance. Plants were taller and had higher biomass and canopy temperature. There was decreased aphid salivation into sieve elements, but no differences in phloem ingestion, indicating that the diminished fitness could be due to poorer tissue quality and unfavourable C:N balance, and that eCO2 was not a factor impeding feeding. Aphid ability to transmit Cucumber mosaic virus (CMV) was studied by exposing source and receptor plants to ambient (427 ppm) or elevated (612 ppm) CO2 before or after virus inoculation. A two-fold decrease on transmission was observed when receptor plants were exposed to eCO2 before aphid inoculation when compared to aCO2.

Hortscience, 2006

. Also the UV-absorbing plastic films were effective in reducing the population density of Frankl... more . Also the UV-absorbing plastic films were effective in reducing the population density of Frankliniella occidentalis (Pergande) and the spread of tomato spotted wilt virus (TSWV) as well as the population density of the lepidopteran pest, Autographa gamma (L.), a common pest of lettuce in Spain. However, no effective control of the greenhouse whitefly Trialeurodes vaporariorum (Westwood) was achieved. The results showed that UV-absorbing plastic films are a very promising tool to protect greenhouse lettuce from the main pests and insect-transmitted virus diseases occurring in northeastern Spain.

En el presente trabajo se ha evaluado durante 2 años consecutivos el grado de eficacia de cubiert... more En el presente trabajo se ha evaluado durante 2 años consecutivos el grado de eficacia de cubiertas agrotextiles en el control de mosca blanca, pulgones y virus en cultivos de lechuga y bróculi en la Comunidad de Madrid y Navarra, respectivamente. También se ha estudiado su efecto sobre el rendimiento y valor comercial del cultivo. Los resultados indican que este tipo de cubiertas puede producir un efecto beneficioso en el cultivo durante el periodo más frío del año (final del otoño al inicio de primavera), reduciendo en algunos casos el daño cosmético producido tanto por pulgones como por mosca blanca. Sin embargo, en caso de no ser retiradas a tiempo, los efectos de las cubiertas pueden ser negativos en cultivos de lechuga, debido a una inducción prematura de floración y reducción del peso por planta.

Journal of General Virology, 2003

Electronic monitoring of aphid stylet activities (EPG technique), transmission tests and electron... more Electronic monitoring of aphid stylet activities (EPG technique), transmission tests and electron microscopy showed that CaMV is preferentially acquired from the phloem by its most common aphid vectors, Brevycorine brassicae and Myzus persicae. We also found that CaMV is semipersistently transmitted and that the rate of acquisition does not follow a typical bimodal curve. Instead, the virus could be acquired from non-phloem tissues at a low and fairly constant rate after one or more intracellular punctures within a few minutes, but the probability of acquisition rose significantly when aphids reached the phase of committed ingestion from the phloem. The acquisition rate of CaMV did not increase with increasing number of intracellular punctures, but the total duration of intracellular puncture was one of the variables selected by the stepwise logistic regression model used to fit the data that best explained acquisition of CaMV. Furthermore, aphids reaching the phloem faster had a higher probability of acquiring the virus. Our results support the hypothesis that multiple intracellular punctures of epidermal and mesophyll cells result in loading aphids with the CaMV-encoded aphid transmission factor (P2), and that aphids, in most cases, subsequently acquire CaMV particles during phloem sap ingestion. Consistently, immunoelectron microscopy showed that P3-virions are frequently found in the sieve element lumen, whereas P2 could not be detected.

Advances in Virus Research, 2012

Virus Research Issn 0168 1702 2014 06 Vol 186 N, Jun 1, 2014

Please cite this article in press as: Carmo-Sousa, M., et al., A non-persistently transmitted-vir... more Please cite this article in press as: Carmo-Sousa, M., et al., A non-persistently transmitted-virus induces a pull-push strategy in its aphid vector to optimize transmission and spread. Virus Res. (2014), http://dx.a b s t r a c t Plant viruses are known to modify the behaviour of their insect vectors, both directly and indirectly, generally adapting to each type of virus-vector relationship in a way that enhances transmission efficiency. Here, we report results of three different studies showing how a virus transmitted in a nonpersistent (NP) manner (Cucumber mosaic virus; CMV, Cucumovirus) can induce changes in its host plant, cucumber (Cucumis sativus cv. Marumba) that modifies the behaviour of its aphid vector (Aphis gossypii Glover; Hemiptera: Aphididae) in a way that enhances virus transmission and spread non-viruliferous aphids changed their alighting, settling and probing behaviour activities over time when exposed to CMV-infected and mock-inoculated cucumber plants. Aphids exhibited no preference to migrate from CMV-infected to mock-inoculated plants at short time intervals (1, 10 and 30 min after release), but showed a clear shift in preference to migrate from CMV-infected to mock-inoculated plants 60 min after release. Our free-choice preference assays showed that A. gossypii alates preferred CMV-infected over mock-inoculated plants at an early stage (30 min), but this behaviour was reverted at a later stage and aphids preferred to settle and reproduce on mock-inoculated plants. The electrical penetration graph (EPG) technique revealed a sharp change in aphid probing behaviour over time when exposed to CMVinfected plants. At the beginning (first 15 min) aphid vectors dramatically increased the number of short superficial probes and intracellular punctures when exposed to CMV-infected plants. At a later stage (second hour of recording) aphids diminished their feeding on CMV-infected plants as indicated by much less time spent in phloem salivation and ingestion (E1 and E2). This particular probing behaviour including an early increase in the number of short superficial probes and intracellular punctures followed by a phloem feeding deterrence is known to enhance the transmission efficiency of viruses transmitted in a NP manner. We conclude that CMV induces specific changes in a plant host that modify the alighting, settling and probing behaviour of its main vector A. gossypii, leading to optimum transmission and spread of the virus. Our findings should be considered when modelling the spread of viruses transmitted in a NP manner.

Neotropical Entomology, 2014

ABSTRACT Plant viruses can directly influence their insect vectors, and indirectly through their ... more ABSTRACT Plant viruses can directly influence their insect vectors, and indirectly through their shared host plant, altering their behavior and performance in a mutualistic or rather antagonistic manner. One of the most studied begomovirus, Tomato yellow leaf curl virus (TYLCV), may also facilitate the expansion of its vector, the whitefly Bemisia tabaci (Gennadius). Considering the likely expansion of the disease and its major vector, we studied the direct and the indirect effects of a Mediterranean isolate of this virus (TYLCV-IL) on the biological performance of the Q biotype of B. tabaci. The following parameters were examined: development time and viability of nymphs, sex ratio, fecundity, and fertility and longevity. The results varied from positive to neutral depending on the parameter and the effect studied. TYLCV accelerated nymphal developmental and increased male longevity of B. tabaci when viruliferous insects developed on TYLCV-immune eggplants (direct effects). An indirect, positive effect of TYLCV-infected plants was observed on fecundity of B. tabaci, which laid more eggs on virus-infected than on noninfected tomato plants. Our results show that TYLCV enhances the population increase of its whitefly vector and that there is a high risk of rapid expansion of both the virus and its vector—the MED species of B. tabaci—into new areas when both agents interact together.

Ann Entomol Soc Amer, 2005

Caulißower mosaic virus (CaMV) is transmitted to crucifers in a noncirculative manner by several ... more Caulißower mosaic virus (CaMV) is transmitted to crucifers in a noncirculative manner by several aphid species. CaMV is preferentially acquired from the phloem, although acquisition also occurs after brief intracellular stylet punctures of aphid vectors in nonvascular leaf tissues. In the present work, we used the electrical penetration graph technique to study the speciÞc aphid stylet activities and behavioral events leading to the inoculation of CaMV to turnip plants by its two major vectors, Brevicoryne brassicae (L.) and Myzus persicae (Sulzer). Aphids subjected to an 8-h acquisition access time on infected plants were transferred to test plants and removed immediately after speciÞc behavioral events were recorded. CaMV was readily inoculated after the Þrst intracellular puncture in nonvascular tissues by both vector species. Inoculation rate of CaMV by B. brassicae was the highest after a 3-h inoculation access period, regardless of whether aphids had reached the phloem phase during that period. Consistent interspeciÞc differences also were found in the ability of both aphid vectors to retain CaMV. B. brassicae could retain the virus after several intracellular punctures, whereas M. persicae readily lost the virus after performing the same number of intracellular stylet punctures. We concluded that salivation by aphids during successive intracellular stylet punctures in the epidermal and mesophyll cells before reaching the phloem phase are the key behavioral events associated to the inoculation of Caulißower mosaic virus. The likely location of the viral retention site inside the aphid mouthparts is discussed.

As technology and transportation create a global community, researchers are increasingly aware of... more As technology and transportation create a global community, researchers are increasingly aware of the need to address widespread crop production challenges using an international perspective. Specific diseases and pests have become universal problems. Potato virus Y (PVY), which is vectored by aphids, has persisted as a problematic disease in potatoes and related crops worldwide. Though the virus is well established in many countries, there have been shifts in the strains dominating each region. For example, the strains present in the United States have shifted from PVYO to PVYNO or PVYNTN. In contrast, in Europe, PVYN is already dominant. Multiple alternative weed hosts have been identified in Europe, which may have contributed to strain dominance. In an effort to understand shifts in strains, a collaborative effort was made to: 1) investigate PVY transmission between known weed hosts and potatoes, and 2) assess vector preferences for healthy or infected plants. Major aphid vectors...

Advances in virus research, 2012

Lettuce is frequently attacked by several viruses causing disease epidemics and considerable yiel... more Lettuce is frequently attacked by several viruses causing disease epidemics and considerable yield losses along the Mediterranean basin. Aphids are key pests and the major vectors of plant viruses in lettuce fields. Lettuce mosaic virus (LMV) is probably the most important because it is seed-transmitted in addition to be transmissible by many aphid species that alight on the crop. Tomato spotted wilt virus (TSWV) is another virus that causes severe damage since the introduction of its major vector, the thrips Frankliniella occidentalis. In regions with heavy and humid soils, Lettuce Mirafiori big-vein virus (LMBVV) can also produce major yield losses.

Spanish Journal of Agricultural Research, 2007

Lettuce mosaic virus (LMV) is transmitted by aphids nonpersistently causing severe disease outbre... more Lettuce mosaic virus (LMV) is transmitted by aphids nonpersistently causing severe disease outbreaks in commercial lettuce crops. New strategies to control plant viruses have arisen based on molecular techniques, which analyze plantvirus-vector interactions. In this work, two PCR-based methods with a previous immunocapture phase, have been developed to detect LMV in single aphids. Detection rates using a RT-nested-PCR method in single aphids and transmission efficiency of Myzus persicae (vector species) and Nasonovia ribisnigri (nonvector species) were compared. Although the percentage of viruliferous aphids for N. ribisnigri (45.8 ± 2.3) was higher than for M. persicae (39.2 ± 3.5) after the same acquisition access period, N. ribisnigri was unable to transmit the virus while M. persicae proved to be an efficient vector (with a transmission rate per single aphid of 10.4 ± 0.8). A method was proposed to estimate vector propensity for nonpersistent viruses based on the relationship between the percentage of viruliferous aphids and their transmission ability. This methodology could be applied to decision-making and implementing control strategies to prevent virus spreading.

Virus Research, 2014

Please cite this article in press as: Carmo-Sousa, M., et al., A non-persistently transmitted-vir... more Please cite this article in press as: Carmo-Sousa, M., et al., A non-persistently transmitted-virus induces a pull-push strategy in its aphid vector to optimize transmission and spread. Virus Res. (2014), http://dx.a b s t r a c t Plant viruses are known to modify the behaviour of their insect vectors, both directly and indirectly, generally adapting to each type of virus-vector relationship in a way that enhances transmission efficiency. Here, we report results of three different studies showing how a virus transmitted in a nonpersistent (NP) manner (Cucumber mosaic virus; CMV, Cucumovirus) can induce changes in its host plant, cucumber (Cucumis sativus cv. Marumba) that modifies the behaviour of its aphid vector (Aphis gossypii Glover; Hemiptera: Aphididae) in a way that enhances virus transmission and spread non-viruliferous aphids changed their alighting, settling and probing behaviour activities over time when exposed to CMV-infected and mock-inoculated cucumber plants. Aphids exhibited no preference to migrate from CMV-infected to mock-inoculated plants at short time intervals (1, 10 and 30 min after release), but showed a clear shift in preference to migrate from CMV-infected to mock-inoculated plants 60 min after release. Our free-choice preference assays showed that A. gossypii alates preferred CMV-infected over mock-inoculated plants at an early stage (30 min), but this behaviour was reverted at a later stage and aphids preferred to settle and reproduce on mock-inoculated plants. The electrical penetration graph (EPG) technique revealed a sharp change in aphid probing behaviour over time when exposed to CMVinfected plants. At the beginning (first 15 min) aphid vectors dramatically increased the number of short superficial probes and intracellular punctures when exposed to CMV-infected plants. At a later stage (second hour of recording) aphids diminished their feeding on CMV-infected plants as indicated by much less time spent in phloem salivation and ingestion (E1 and E2). This particular probing behaviour including an early increase in the number of short superficial probes and intracellular punctures followed by a phloem feeding deterrence is known to enhance the transmission efficiency of viruses transmitted in a NP manner. We conclude that CMV induces specific changes in a plant host that modify the alighting, settling and probing behaviour of its main vector A. gossypii, leading to optimum transmission and spread of the virus. Our findings should be considered when modelling the spread of viruses transmitted in a NP manner.

Phytopathology, 2012

Vidal, E., Yokomi, R. K., Moreno, A., Bertolini, E., and Cambra, M. 2012. Calculation of diagnost... more Vidal, E., Yokomi, R. K., Moreno, A., Bertolini, E., and Cambra, M. 2012. Calculation of diagnostic parameters of advanced serological and molecular tissue-print methods for detection of Citrus tristeza virus: A model for other plant pathogens. Phytopathology 102:114-121.

Virus Research, 2009

Homopterans including aphids, whiteflies and leafhoppers are the major vectors of viruses compris... more Homopterans including aphids, whiteflies and leafhoppers are the major vectors of viruses comprising more than 80% of insect-transmitted viruses which represents close to 400 virus species within 39 different genera. Host plant recognition by homopterans requires a series of steps that are linked to plant virus transmission, including host searching or pre-alighting behaviour, probing on superficial tissues, settlement and stylet penetration to the target feeding tissues and salivation and continuous sap ingestion from the preferred feeding site. This review considers how vector behaviour influences the transmission and spread of plant viruses depending on the type of virus-vector relationship. Most studies have concentrated on aphid-transmitted viruses and particular probing and feeding behavioural processes and activities leading to the transmission of cuticula-borne and circulative viruses have been identified. The review also focuses on which are the most likely retention sites within the insect's body of cuticula-borne viruses. Finally, the influences of virus infection on vector behaviour such as changes in the attractiveness, settlement or feeding preference together with changes on vector performance (development, fecundity, rate of population increase and survival) are discussed.

Plant Pathology, 2012

The control of Plum pox virus (PPV), the most important viral disease that affects stone fruit tr... more The control of Plum pox virus (PPV), the most important viral disease that affects stone fruit trees, requires the use of reliable detection methods. The effectiveness of spot real-time reverse transcriptase polymerase chain reaction (RT-PCR) for the detection of PPV in samples collected from nursery blocks was compared with a validated PPV detection technique, the double antibody sandwich indirect enzyme-linked immunosorbent assay (DASI-ELISA) using the PPV-specific monoclonal antibody 5B-IVIA ⁄ AMR. In total, 5047 nursery plants were analysed by both techniques. The agreement between the techniques was almost perfect (Cohen's kappa index of 0AE88 ± 0AE01). The diagnostic parameters (sensitivity, specificity and likelihood ratios) of both techniques were simultaneously evaluated in 2473 nursery plants by latent class models using maximum likelihood functions and a Bayesian approach. The sensitivity and specificity of both techniques did not vary according to the latent model applied. Spot real-time RT-PCR was more sensitive while DASI-ELISA was more specific for PPV detection. In addition, the findings demonstrate that latent class models are a flexible and potent statistical method to estimate the accuracy of diagnostic tests for plant pathology.

Journal of Virology, 2005

Viruses frequently use insect vectors to effect rapid spread through host populations. In plant v... more Viruses frequently use insect vectors to effect rapid spread through host populations. In plant viruses, vector transmission is the major mode of transmission, used by nearly 80% of species described to date. Despite the importance of this phenomenon in epidemiology, the specificity of the virus-vector relationship is poorly understood at both the molecular and the evolutionary level, and very limited data are available on the precise viral protein motifs that control specificity. Here, using the aphid-transmitted Cauliflower mosaic virus (CaMV) as a biological model, we confirm that the "noncirculative" mode of transmission dominant in plant viruses (designated "mechanical vector transmission" in animal viruses) involves extremely specific virus-vector recognition, and we identify an amino acid position in the "helper component" (HC) protein of CaMV involved in such recognition. Site-directed mutagenesis revealed that changing the residue at this position can differentially affect transmission rates obtained with various aphid species, thus modifying the spectrum of vector species for CaMV. Most interestingly, in a virus line transmitted by a single vector species, we observed the rapid appearance of a spontaneous mutant specifically losing its transmissibility by another aphid species. Hence, in addition to the first identification of an HC motif directly involved in specific vector recognition, we demonstrate that change of a virus to a different vector species requires only a single mutation and can occur rapidly and spontaneously.

Journal of General Virology, 2012

Inoculation of the semi-persistent cauliflower mosaic virus (CaMV, genus Caulimovirus) is associa... more Inoculation of the semi-persistent cauliflower mosaic virus (CaMV, genus Caulimovirus) is associated with successive brief (5-10 s) intracellular stylet punctures (pd) when aphids probe in epidermal and mesophyll cells. In contrast to non-persistent viruses, there is no evidence for which of the pd subphases (II-1, II-2 and II-3) is involved in the inoculation of CaMV. Experiments were conducted using the electrical penetration graph (EPG) technique to investigate what particular subphases of the pd are associated with the inoculation of CaMV to turnip by its aphid vector Brevicoryne brassicae. In addition, the same aphid species/test plant combination was used to compare the role of the pd subphases in the inoculation of the non-persistent turnip mosaic virus (TuMV, genus Potyvirus). Inoculation of TuMV was found to be related to subphase II-1, confirming earlier results, but CaMV inoculation appeared to be related exclusively to subphase II-2 instead. The mechanism of CaMV inoculation and the possible nature of subphase II-2 are discussed in the scope of our findings. %paper no. vir037887 charlesworth ref: vir037887& Plant

Entomologia Experimentalis et Applicata, 2014

ABSTRACT The tomato potato psyllid (TPP), Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), i... more ABSTRACT The tomato potato psyllid (TPP), Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is the main vector of the bacterium Candidatus Liberibacter solanacearum (Lso), a major disease of solanaceous crops. Feeding of TPP is associated with Lso transmission. However, very little is known about the stylet penetration activities linked to acquisition and inoculation of Lso. The electrical penetration graph (EPG)-DC system was used to monitor stylet penetration activities during acquisition and inoculation of Lso by individual TPP on tomato [Solanum lycopersicum L. (Solanaceae)]. Female TPP from Lso-free and Lso-infected colonies were used in acquisition and inoculation tests, respectively. In the acquisition tests, TPP were tested for Lso after EPG recording of their stylet penetration activities on Lso-infected tomato shoots. In the inoculation tests, samples from the tomato plants on which the stylet penetration of Lso-infected TPP had been recorded were tested for Lso infection. The relationships between qPCR results and the EPG waveforms (C, G, D, E1, and E2) representing the main stylet penetration activities performed by individual insects in inoculation and acquisition tests were investigated. Results confirmed that a single adult TPP is capable of infecting a plant with Lso. Our data suggest that acquisition of the bacteria occurs during phloem ingestion (E2), and inoculation is likely associated with salivation into the phloem sieve elements (E1). The durations of EPG parameters were not significantly different between Lso-infected and Lso-free TPP (later shown by qPCR) in acquisition tests. In inoculation tests, the durations of E1 or E2 recorded from TPP on Lso-infected and Lso-free plants that were later shown by qPCR were not significantly different. However, C was shorter on Lso-infected plants than on Lso-free plants, where TPP performed phloem activities. The minimum plant access period required for Lso transmission by a single TPP was estimated to be ca. 2 h, with an acquisition threshold of about 36 min.

Archives of Virology, 2009

The viral charge acquired and inoculated by single aphids in a non-circulative transmission is es... more The viral charge acquired and inoculated by single aphids in a non-circulative transmission is estimated using plum pox virus (PPV). A combination of electrical penetration graph and TaqMan real-time RT-PCR techniques was used to establish the average number of PPV RNA targets inoculated by an aphid in a single probe (26,750), approximately half of the acquired ones. This number of PPV targets is responsible for a systemic infection of 20% on the inoculated receptor plants. No significant differences were found between the number of PPV RNA targets acquired after one and after five intracellular punctures (pd), but the frequency of infected receptor plants was higher after 5 pd. The percentage of PPV-positive leaf discs after just 1 pd of inoculation probe (28%/4,603 targets) was lower than after 5 pd (45.8%/135 9 10 6 targets). The methodology employed could be easily extended to other virus-vector-host combinations to improve the accuracy of models used in virus epidemiology.

Annals of the Entomological Society of America, 2005

Caulißower mosaic virus (CaMV) is transmitted to crucifers in a noncirculative manner by several ... more Caulißower mosaic virus (CaMV) is transmitted to crucifers in a noncirculative manner by several aphid species. CaMV is preferentially acquired from the phloem, although acquisition also occurs after brief intracellular stylet punctures of aphid vectors in nonvascular leaf tissues. In the present work, we used the electrical penetration graph technique to study the speciÞc aphid stylet activities and behavioral events leading to the inoculation of CaMV to turnip plants by its two major vectors, Brevicoryne brassicae (L.) and Myzus persicae (Sulzer). Aphids subjected to an 8-h acquisition access time on infected plants were transferred to test plants and removed immediately after speciÞc behavioral events were recorded. CaMV was readily inoculated after the Þrst intracellular puncture in nonvascular tissues by both vector species. Inoculation rate of CaMV by B. brassicae was the highest after a 3-h inoculation access period, regardless of whether aphids had reached the phloem phase during that period. Consistent interspeciÞc differences also were found in the ability of both aphid vectors to retain CaMV. B. brassicae could retain the virus after several intracellular punctures, whereas M. persicae readily lost the virus after performing the same number of intracellular stylet punctures. We concluded that salivation by aphids during successive intracellular stylet punctures in the epidermal and mesophyll cells before reaching the phloem phase are the key behavioral events associated to the inoculation of Caulißower mosaic virus. The likely location of the viral retention site inside the aphid mouthparts is discussed.

Scientific Reports, 2016

Increasing atmospheric carbon dioxide (CO2) impacts plant growth and metabolism. Indirectly, the ... more Increasing atmospheric carbon dioxide (CO2) impacts plant growth and metabolism. Indirectly, the performance and feeding of insects is affected by plant nutritional quality and resistance traits. Life history and feeding behaviour of Myzus persicae were studied on pepper plants under ambient (aCO2, 400 ppm) or elevated CO2 (eCO2, 650 ppm), as well as the direct impact on plant growth and leaf chemistry. Plant parameters were significantly altered by eCO2 with a negative impact on aphid's life history. Their pre-reproductive period was 11% longer and fecundity decreased by 37%. Peppers fixed significantly less nitrogen, which explains the poor aphid performance. Plants were taller and had higher biomass and canopy temperature. There was decreased aphid salivation into sieve elements, but no differences in phloem ingestion, indicating that the diminished fitness could be due to poorer tissue quality and unfavourable C:N balance, and that eCO2 was not a factor impeding feeding. Aphid ability to transmit Cucumber mosaic virus (CMV) was studied by exposing source and receptor plants to ambient (427 ppm) or elevated (612 ppm) CO2 before or after virus inoculation. A two-fold decrease on transmission was observed when receptor plants were exposed to eCO2 before aphid inoculation when compared to aCO2.

Hortscience, 2006

. Also the UV-absorbing plastic films were effective in reducing the population density of Frankl... more . Also the UV-absorbing plastic films were effective in reducing the population density of Frankliniella occidentalis (Pergande) and the spread of tomato spotted wilt virus (TSWV) as well as the population density of the lepidopteran pest, Autographa gamma (L.), a common pest of lettuce in Spain. However, no effective control of the greenhouse whitefly Trialeurodes vaporariorum (Westwood) was achieved. The results showed that UV-absorbing plastic films are a very promising tool to protect greenhouse lettuce from the main pests and insect-transmitted virus diseases occurring in northeastern Spain.

En el presente trabajo se ha evaluado durante 2 años consecutivos el grado de eficacia de cubiert... more En el presente trabajo se ha evaluado durante 2 años consecutivos el grado de eficacia de cubiertas agrotextiles en el control de mosca blanca, pulgones y virus en cultivos de lechuga y bróculi en la Comunidad de Madrid y Navarra, respectivamente. También se ha estudiado su efecto sobre el rendimiento y valor comercial del cultivo. Los resultados indican que este tipo de cubiertas puede producir un efecto beneficioso en el cultivo durante el periodo más frío del año (final del otoño al inicio de primavera), reduciendo en algunos casos el daño cosmético producido tanto por pulgones como por mosca blanca. Sin embargo, en caso de no ser retiradas a tiempo, los efectos de las cubiertas pueden ser negativos en cultivos de lechuga, debido a una inducción prematura de floración y reducción del peso por planta.

Journal of General Virology, 2003

Electronic monitoring of aphid stylet activities (EPG technique), transmission tests and electron... more Electronic monitoring of aphid stylet activities (EPG technique), transmission tests and electron microscopy showed that CaMV is preferentially acquired from the phloem by its most common aphid vectors, Brevycorine brassicae and Myzus persicae. We also found that CaMV is semipersistently transmitted and that the rate of acquisition does not follow a typical bimodal curve. Instead, the virus could be acquired from non-phloem tissues at a low and fairly constant rate after one or more intracellular punctures within a few minutes, but the probability of acquisition rose significantly when aphids reached the phase of committed ingestion from the phloem. The acquisition rate of CaMV did not increase with increasing number of intracellular punctures, but the total duration of intracellular puncture was one of the variables selected by the stepwise logistic regression model used to fit the data that best explained acquisition of CaMV. Furthermore, aphids reaching the phloem faster had a higher probability of acquiring the virus. Our results support the hypothesis that multiple intracellular punctures of epidermal and mesophyll cells result in loading aphids with the CaMV-encoded aphid transmission factor (P2), and that aphids, in most cases, subsequently acquire CaMV particles during phloem sap ingestion. Consistently, immunoelectron microscopy showed that P3-virions are frequently found in the sieve element lumen, whereas P2 could not be detected.