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Using an enriched library method, seven polymorphic microsatellite loci were isolated from the barley stem gall midge, Mayetiola hordei. Polymorphism at loci was surveyed on 57 individual midges collected on barley in Tunisia. Across loci, polymorphism ranged from two to six alleles per locus. The observed heterozygosity varied between 0.070 and 0.877. Based on the number of alleles detected and the associated levels of heterozygosity, we believe that these loci will prove useful for population genetic studies on M. hordei.

The tomato leaf miner Tuta absoluta Meyrick has invaded tomato (Solanum lycopersicum L.) crop in Tunisia since 2008 and is representing today a major threat to the production of this crop. In this study, we used the Randomly Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) technology to assess the genetic variability within and among seven populations of T. absoluta, collected on tomato from different regions in Tunisia. Using five RAPD-PCR primers and 108 individuals, 140 polymorphic fragments were recorded. From 335 different RAPD phenotypes generated, 71 were redundant and 264 unique to a specific population. The genetic structure of T. absoluta was investigated using analysis of molecular variance (AMOVA), genetic distances (Fst) and multidimensional scaling (MDS). We detected a high genetic diversity within and among populations in conjunction with a significant differentiation between populations, suggesting that different founder genotypes would have been responsible of the introduction of T. absoluta in Tunisia. The presence of overlapping phenotypes probably indicates migration events between populations, mainly through infested plant material carried by humans.El minador de hojas de tomate Tuta absoluta Meyrick ha invadido el cultivo del tomate (Solanum lycopersicum L.) en Túnez desde 2008 y actualmente representa una importante amenaza para su producción. En este estudio usamos la tecnología de ADN polimórfico amplificado al azar-reacción de cadena polimerasa (RAPD-PCR) para evaluar la variabilidad genética dentro y entre siete poblaciones de T. absoluta, colectadas desde tomate en diferentes regiones de Túnez. Usando cinco primers RAPD-PCR y 108 individuos, se registraron 140 fragmentos polimórficos. Se generaron 335 fenotipos RAPD diferentes, entre los cuales 71 fueron redundantes y 264 únicos para una población específica. La estructura genética de T. absoluta se investigó usando análisis de varianza molecular (AMOVA), distancias genéticas (Fst) y escalamiento multidimensional (MDS). Detectamos una alta diversidad genética dentro y entre poblaciones en conjunto con una diferenciación significativa entre poblaciones, sugiriendo que los genotipos fundadores podrían haber sido responsables de la introducción de T. absoluta en Túnez. La presencia de fenotipos superpuestos probablemente indica eventos de migración entre poblaciones, principalmente a través de material vegetal infestado transportado por humanos.

Hessian fly, Mayetiola destructor (Say), is a destructive pest of wheat worldwide and an endemic pest in Tunisia. Two natural populations of this insect from the North of Tunisia were evaluated, in the field, for their virulence, based on response developed by bread wheat (Triticum aestivum L.) cultivars carrying H3, H5, H6, H7H8, H11, H13 and H16 resistance genes. H11, H13 and H16 showed a high effectiveness against both populations; therefore, their implication in Hessian fly breeding programs would be of interest. The level of infestation, as well as the yield loss, was assessed, based on the percentage of infested plants and variation in growth parameters due to infestation. The percentage of infested plants, over a 2-yr period in Mateur, averaged 18.82% for durum wheat (Triticum turgidum L. subsp. durum (Desf.) Husn.) and 32.50% for bread wheat. For the improved durum wheat cv. Karim used as reference, the plant height, number of internodes, number of productive tillers per plant, and 100-seed weight were negatively affected by infestation, while the number of tillers per plant was positively affected. Aiming to update information about the annual number of the fly generations occurring on wheat, we surveyed infestation in Jédéida. At least three Hessian fly generations were detected on bread wheat and durum wheat. Continued regular surveying of Hessian fly populations in terms of virulence, impact on yield and annual generations is required for optimal deployment of resistance genes and integrated management of Hessian fly across all wheat production areas.La mosca de Hess, Mayetiola destructor (Say), es una plaga mundial destructiva del trigo y endémica en Túnez. Se evaluaron dos poblaciones naturales de este insecto desde el Norte de Túnez, en el campo, por su virulencia, basado en la respuesta desarrollada por cultivares de trigo panadero (Triticum aestivum L.) portando los genes de resistencia H3, H5, H6, H7H8, H11, H13 y H16. H11, H13 and H16 mostraron una alta efectividad contra ambas poblaciones; por lo tanto, su implicancia en programas de producción de mosca de Hess podría ser de interés. Se evaluaron el nivel de infestación y la pérdida de rendimiento, basado en el porcentaje de plantas infestadas y variación en parámetros de crecimiento debidos a infestación. El porcentaje de plantas infestadas, en un período de 2 años en Mateur, promedió 18,82% para trigo candeal (Triticum turgidum L. subsp. durum (Desf.) Husn.) y 32,50% para trigo panadero. Para el trigo candeal mejorado cv. Karim usado como referencia, altura de planta, número de entrenudos, número de cañas productivas por planta, y peso de 100 semillas fueron negativamente afectados por infestación, mientras el número de cañas por planta fue positivamente afectado. Con el fin de actualizar la información sobre el número anual de las generaciones de mosca en trigo, investigamos infestación en Jédeida. Al menos tres generaciones de mosca de Hess se detectaron en trigo panadero y candeal. Se requieren ensayos regulares de virulencia, impacto en rendimiento, y generaciones anuales de poblaciones de mosca de Hess para un óptimo despliegue de genes de resistencia y manejo integrado de la mosca por todas las áreas productoras de trigo.

The tomato leaf miner Tuta absoluta Meyrick has invaded tomato ( Solanum lycopersicum L.) crop in Tunisia since 2008 and is representing today a major threat to the production of this crop. In this study, we used the Randomly Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) technology to assess the genetic variability within and among seven populations of T. absoluta, collected on tomato from different regions in Tunisia. Using five RAPD-PCR primers and 108 individuals, 140 polymorphic fragments were recorded. From 335 different RAPD phenotypes generated, 71 were redundant and 264 unique to a specific population. The genetic structure of T. absoluta was investigated using analysis of molecular variance (AMOVA), genetic distances (Fst) and multidimensional scaling (MDS). We detected a high genetic diversity within and among populations in conjunction with a significant differentiation between populations, suggesting that different founder genotypes would have been responsible of the introduction of T. absoluta in Tunisia. The presence of overlapping phenotypes probably indicates migration events between populations, mainly through infested plant material carried by humans.

Ten microsatellites were isolated from the barley stem gall midge, Mayetiola hordei. Polymorphism at each locus was tested on 40 individual midges, among which 34 were collected on barley and six on wheat crops in Tunisia. Six loci were polymorphic with the number of alleles ranging from two to seven. The observed heterozygosity varied between 0.025 and 0.2. These microsatellite loci revealed a strong effect of host plant on the population genetic structure of M. hordei.

International audience; Fourteen microsatellite loci were isolated and characterized in the potato aphid, Macrosiphum euphorbiae Thomas, by screening a genomic library with the oligonucleotide probes (GA)(10) (GT)(10) and (GATA)(4). Allelic diversity was estimated in samples collected from potato fields in Tunisia. Ten loci displayed polymorphism that ranged from two to four alleles per locus and the observed heterozygosity ranged from zero to one. These markers could be used to study the population genetic structure of this polyphagous aphid species.

In Morocco, two sympatric species of Mayetiola (destructor and hordei) have been identified on the basis of microscopic characters. Barley is almost exclusively colonized by M. hordei and presents distinct stem swellings (galls), whereas wheat is almost exclusively colonized by M. destructor and has no gall. In Tunisia, previous studies have shown that Mayetiola infestations of wheat or barley never produce galls in the northern region, whereas galls are frequent on barley in the center and the rule in the south. In the present study, we have investigated the electrophoretic polymorphism at four loci of Mayetiola collected on field plants presenting or lacking galls from northern and central Tunisia. We showed that, in central Tunisia, two reproductively isolated groups were present in all samples from wheat, barley and oat whether these plants carried gall or not. In contrast, only one of these groups was found in samples from wheat and barley lacking galls from the north. On the basis of a comparison with Moroccan strains of the two species, these groups were identified as M. hordei and M. destructor which can easily be characterized by diagnostic alleles at two loci, Pgi and Mdh2.