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Fiallo-Olive E.,University of Malaga | Espino A.I.,Laboratorio Of Sanidad Vegetal | Botella-Guillen M.,Laboratorio Of Sanidad Vegetal | Gomez-Gonzalez E.,Laboratorio Of Sanidad Vegetal | And 2 more authors.
Plant Disease

In March 2013, symptoms of mild leaf curling, mosaic, and interveinal yellowing were observed in tobacco (Nicotiana tabacum) plants grown in a row surrounding the exterior of a greenhouse containing a tomato crop in Guía de Isora, Tenerife (Canary Islands, Spain). The tobacco plants were found lightly infested by the whitefly (Hemiptera: Aleyrodidae) Bemisia tabaci. The greenhouses in this area are devoted to the commercial production of tomato. The farmers grow some tobacco plants inside and outside of them as a reservoir of parasitoids and depredators of B. tabaci. This insect is the natural vector of the main viruses severely affecting tomato in the Canary Islands, the begomovirus Tomato yellow leaf curl virus and the crinivirus Tomato chlorosis virus (ToCV). ToCV was detected in Spain in 1997 (2) and has become established in most of the coastal provinces of eastern and southern continental Spain and in the Canary Islands. Approximately 50% of the tomato plants grown inside the greenhouse close to the tobacco plants showed typical ToCV symptoms, and infection by this virus was confirmed in the seven plants tested by reverse transcription (RT)-PCR using specific coat protein gene (CP) primers (see below). Total RNA was extracted with TRIzol Reagent (Invitrogen) from leaves of five tobacco plants showing the symptoms mentioned above and analyzed by dot-blot hybridization using digoxigenin-labeled RNA probes to the CP gene of ToCV. Positive signal was obtained for all five plants. RT-PCR reactions were performed with specific primers for the detection of ToCV, MA380(+) (5′-GTGAGACCCCGATGACAGAT-3′) and MA381(-) (5′-TACAGTTCCTTGCCCTCGTT-3′), specific to the CP gene (ToCV RNA 2) (3), and MA396(+) (5′-TGGTCGAACAGTTTGAGAGC-3′) and MA397(-) (5′-TGAACTCGAATTGGGACAGA-3′), specific to the RNA-dependent RNA polymerase (RdRp) gene (ToCV RNA 1) (1). DNA fragments of the expected size (436 and 763 bp, respectively) were obtained, thus supporting the presence of ToCV in the symptomatic samples. The amplified product of the RdRp gene fragment from one sample was directly sequenced (Macrogen Inc., South Korea) and resulted closely related to ToCV isolates from Sudan (GenBank Accession No. JN411686, 99.6% nt identity) and Spain (DQ983480, 99.4% nt identity), thereby confirming the infection by this virus. Partial sequence of the ToCV isolate from tobacco was deposited in GenBank under accession no. KJ175084. In addition, all five plants resulted positive when analyzed by ELISA for Tomato spotted wilt virus and Potato virus Y and by PCR for Tomato yellow leaf curl virus (data not shown), all three viruses reported to infect naturally tobacco. Although tobacco has been reported as an experimental host of ToCV (4), to our knowledge, this is the first report of this species as a natural host of this virus. The finding of ToCV infecting tobacco raises the question of whether this virus could emerge as a pathogen of this crop and questions the use that farmers make of tobacco as reservoirs of natural enemies for whitefly control in tomato. © 2014 The American Phytopathological Society. Source

Torres-Vila L.M.,Servicio de Sanidad Vegetal | Rodriguez-Molina M.C.,Research Center Agraria Finca La Orden Valdesequera
Arthropod-Plant Interactions

It is widely assumed that in the late nineteenth century Lobesia botrana Den. and Schiff. shifted its food source from a wild shrub (Daphne gnidium L.) to vine (Vitis vinifera L.). We explored if host range expansion reflects an evolutionary host shift, whereby the new moth-host association was linked to adaptive changes. The reaction norms of larval survival, adult weight and development time were investigated in L. botrana under field conditions. Two moth strains were established from vine and daphne, and reciprocal infestations with neonate larvae were performed on both host plants over the three larval generations. All three traits showed phenotypic plasticity and genetic variation, variation for plasticity being only detected in larval survival. Comparisons between hosts within strains showed that (1) larval survival was higher on vine in 9 of 12 cases, (2) adult weight was lower on vine only in the first generation and (3) development time was shorter on vine in first generation, shorter on daphne in third generation and displayed a sex-related response in the second generation. Comparisons between strains within hosts evidenced moth-host adaptation as larval survival increased when strains developed on its original host. There was also evidence of moth-parasitoid coevolution because parasitism level was strain-dependent. We hypothesize that higher larval survival on vine, similar adult weight on both hosts in summer generations and lower predation risk in vineyards, might be among the fitness-related factors explaining evolutionary host shift to and worldwide adaptive success on vine of L. botrana. © 2012 Springer Science+Business Media Dordrecht. Source

Torres-Vila L.M.,Servicio de Sanidad Vegetal
Journal of Evolutionary Biology

Polyandry is perhaps the most puzzling component of mating systems because the fitness benefits for females of mating with more than one male during lifetime are poorly understood. The occurrence and extent of polyandry varies considerably both among and within species, and a positive association between polyandry and fecundity is widespread but not universal. The scenario is further complicated because the scientific literature on this issue includes studies that are often inconclusive or contradictory even for the same target species. A previous meta-analysis detected the crucial importance of two usually neglected aspects that potentially bias the interpretation of primary studies about the polyandry-fecundity relationship: the methodological approach - experimental or descriptive - and the polyandry concept itself - realized or potential. In this paper, we experimentally test the effect of these aspects with the moth Lobesia botrana. We used an innovative protocol in which the experimental and the descriptive methods were conducted simultaneously on the same target population and the results were then interpreted from the perspective of both concepts of polyandry. The results clearly showed that 1) the conclusions about the polyandry-fecundity relationship were strongly dependent on the methodological approach used and 2) the concept of polyandry invoked by the researcher was a confounding effect that potentially biases data interpretation. We suggest that greater attention must be paid to intraspecific variation among females in their propensity to remate. The differentiation in experimental studies between potentially polyandrous and monandrous phenotypes could greatly improve our knowledge about the maintenance of female mating polymorphism in most species and the adaptive significance of polyandry. © 2012 European Society For Evolutionary Biology. Source

Rodriguez-Molina M.C.,Research Center Agraria | Morales-Rodriguez M.C.,Research Center Agraria | Palo Osorio C.,Research Center Agraria | Palo Nunez E.,Research Center Agraria | And 3 more authors.
Spanish Journal of Agricultural Research

Root and crown rot (Tristeza disease) is an increasing problem for red pepper crop in La Vera region (Cáceres, western Spain). Field surveys were carried on in 2006 and 2007 to identify the causal agents of this disease. A Phytophthora species was isolated from diseased plants in most of the surveyed fields (27 of 36 in 2006 and 15 of 16 in 2007), while Verticillium spp. were not detected. Fifteen Phytophthora isolates were examined and identified as P. nicotianae, all of them were heterothalic isolates of mating type A2. Pathogenicity tests conducted on 'Jaranda'red pepper plants developed symptoms of wilt and root and crown rot, although disease severity differed significantly (P < 0.001) among isolates. Results indicate that P. nicotianae is the principal causal agent of the Tristeza disease of red pepper plants in La Vera region and this has several implications for the development of future disease management strategies. The host range of isolates from red pepper plants should be studied in order to establish suitable crop rotation in this region. Source

Arrizubieta M.,Institute Agrobiotecnologia | Simon O.,Institute Agrobiotecnologia | Torres-Vila L.M.,Servicio de Sanidad Vegetal | Figueiredo E.,University of Lisbon | And 5 more authors.
Pest Management Science

BACKGROUND: A binary co-occluded mixture (HearSP1B:LB6) of Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) variants was previously found to be highly pathogenic under laboratory conditions. The insecticidal efficacy and persistence of this mixture were determined in greenhouse and field-grown tomato crops in Spain and Portugal. RESULTS: Concentrations of 109-1011 occlusion bodies (OBs) L-1 of HearSP1B:LB6 resulted in 89-100% mortality of larvae on treated tomato plants in growth chambers. In protected tomato crops, application of 1010 OBs L-1 of HearSP1B:LB6 was as effective as Bacillus thuringiensis (Bt) and spinosad in reducing the percentage of damaged fruits, and resulted in higher larval mortality than the Bt treatment. In open-field tomato crops, virus treatments were as effective in reducing the percentage of damaged fruit as spinosad, Bt and chlorpyrifos treatments. The persistence of the insecticides on tomato plants was negatively correlated with solar radiation in both field and greenhouse settings. Residual insecticidal activity of OBs on protected tomato crops at 6 days post-application was 55 and 35% higher than that of Bt and spinosad respectively. On field-grown tomato, OB persistence was significantly lower than with spinosad or chlorpyrifos. CONCLUSION: The efficacy and persistence of HearSP1B:LB6 OBs were comparable with those of commercial insecticides in both field and greenhouse tomato crops. Future studies should focus on reducing application rates to determine insecticidal efficacy at lower OB concentrations. © 2015 Society of Chemical Industry. Source

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