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Calvo D.,Institute Ciencias Agrarias Consejo Superior Of Investigaciones Cientificas | Fereres A.,Institute Ciencias Agrarias Consejo Superior Of Investigaciones Cientificas
BioControl | Year: 2011

Plant viruses and aphids can interact via contest competition for plant resources and induce changes in plant physiology, which can have effects on a third trophic level. The aim of this study was to determine how the interactions between a circulative plant virus and its aphid vector may affect the performance of an endoparasitoid and how parasitism may affect the efficiency of virus transmission by its aphid vector. The timing when parasitized aphids were transferred to virus-infected lettuce leaves was critical for the performance of A. ervi. Higher parasitoid larvae mortality, longer developmental times and lower percentages of mummification were detected on viruliferous/parasitized aphid nymphs when the time lag between parasitism and exposure to the virus was less than 24 h. No significant differences were detected in virus transmission rate between parasitized and non-parasitized M. euphorbiae aphids. © 2011 International Organization for Biological Control (IOBC).


Cid M.,Institute Ciencias Agrarias Consejo Superior Of Investigaciones Cientificas | Avila A.,Zeta Seeds S.L. | Garcia A.,Zeta Seeds S.L. | Abad J.,Zeta Seeds S.L. | Fereres A.,Institute Ciencias Agrarias Consejo Superior Of Investigaciones Cientificas
Arthropod-Plant Interactions | Year: 2012

The use of resistant cultivars is one of the best ways to protect lettuce from aphid pests. At present, there are cultivars available with nearly complete resistance to Nasonovia ribisnigri biotype Nr:0 (based on the Nr gene) and partial resistance to Macrosiphum euphorbiae. Nevertheless, a new biotype of N. ribisnigri (Nr:1) able to overcome the resistance based on the Nr gene is expanding around Europe and has become a major threat of lettuce. In the present work, we report the presence of this new biotype in southeastern Spain, a major lettuce-producing region. Furthermore, a pool of 264 germplasm accessions belonging to Lactuca genus was tested in a greenhouse assay to search for new resistance sources to N. ribisnigri. The most promising accessions were retested in the laboratory to characterize the resistance by means of free-choice and antibiosis assays against biotypes Nr:0 and Nr:1 of N. ribisnigri and against a clone of M. euphorbiae. Three accessions of L. virosa showed resistance against the target aphid species and could be of interest for ongoing breeding programs. The accessions CGN16272 and CGN13361 were both partially resistant to the Nr:1 biotype of N. ribisnigri and to M. euphorbiae, and CGN13355, in spite of not being resistant to N. ribisnigri, showed a near complete resistance to M. euphorbiae. The study of the feeding behavior of N. ribisnigri biotypes showed that the Nr:1 biotype is able to maintain a similar phloem feeding ingestion pattern on genotypes bearing the Nr gene and on N. ribisnigri-susceptible lettuce genotypes. Moreover, as aphids rejected L. virosa as a feeding source due to superficial factors (high level of antixenosis), no differences in the level of antibiosis between such genotypes were detected. A second set of screening assays were conducted on 40 accessions of L. virosa in order to select for resistance against the Nr:1 biotype. The results showed three accessions with high levels of resistance (CGN05148, CGN21399 and CGN16274) against Nr:1 that could be of interest in lettuce breeding programs. © 2012 Springer Science+Business Media B.V.

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