Miguel Escuer

Incidence of the pinewood nematode Bursaphelenchus xylophlius Steiner & Buhrer, 1934 (Nickle, 1970) in Spain

The pine wood nematode (PWN) Bursaphelenchus xylophilus Steiner & Buhrer, 1934 (Nickle, 1970), is a pathogenic species in the genus Bursaphelenchus Fuchs, 1937. The introduction and establishment of PWN in the Setubal Peninsula, Portugal (Mota et al., 1999), and the evidence that Monochamus galloprovincialis is its insect vector in this country (Sousa et al., 2001), has stimulated studies on its further distribution and its potential vector insects in Europe, including Spain. There is a clear risk of spread of pine wood nematode into Spanish territory from Portugal, both as a result of natural spread and due to the important timber trade between the two countries. The occurrence of Bursaphelenchus spp. in Spain has been previously studied (Abelleira et al., 2002, 2003; Escuer et al., 2003, 2004; Robertson et al., 2008). These studies have shown, in addition, the distribution of insects belonging to the Cerambycidae, Curculionidae and Scolytidae families (Cobos, 1986; Gil Sánchez & Pajares Alonso, 1986; Vives, 2000; Verdugo Paez, 2004), which are known to be vectors of Bursaphelenchus spp. other than B. xylophilus and are often found to be associated with stressed, dead or decaying conifers. Although it is generally accepted that B. xylophilus is the only truly pathogenic species (reviewed by Jones et al., 2008), other species may be involved in pine forest decline in some European regions or, alternatively, may simply be opportunistic infectors of stressed trees (Mamiya, 1999; Caroppo et al., 2000; Skarmoutsos et al., 2000). Pinus pinaster is the most representative

Effect of mine tailing on the spatial variability of soil nematodes from lead pollution in La Union (Spain)

The Cartagena-La Union mining district, exploited since the end of the 3rd century BC, was one of the worlds largest lead producers in the 19th century. Although activity ceased in 1991, today mining residues pose a huge pollution problem. This study characterises lead contents (total and DPTA) and other soil parameters (N, P, K, pH, SOM, CaCO3, granulometric fraction, etc.) using multivariate geostatistical methods in relation to nematode diversity. In this work, trophic groups and metabolic footprints of soil nematodes were measured using 193 samples from the mining, natural and agricultural areas in this district. We explored the relationship between soil health and nematode communities. High lead concentrations were quantified: mean 8,500 mg kg(-1) for total and 340 mg kg(-1) for DPTA in this mining area. Although nematode diversity was broad (81 taxa), their diversity, abundance and metabolic footprints significantly reduced in the mining area. Significant differences in the nematode community structure were observed, and the relative abundance of predators was sensitive to mine and agricultural activities, whilst omnivores reduced only in the agricultural area, and bacterial feeders exhibited a differential response to both anthropogenic disturbances. The total abundance of nematodes, trophic groups and c-p groups correlated negatively with soil Pb contents, and a positive relationship was found with SOM and N, P and K contents.

New host races of Meloidogyne arenaria, M. incognita, and M. javanica from horticultural regions of Spain.

In total, 140 populations of the genus Meloidogyne collected from representative horticultural regions of Spain and maintained at the Department of Agroecology, Institute of Agrarian Sciences, Madrid were characterized using perineal morphology, sequenced characterized amplified region polymerase chain reaction with species-specific primers, and bioassay. Using a modified North Carolina differential host test as a basis, 13 Meloidogyne populations did not fit into the published race scheme. These populations had very limited host ranges, reproducing only on susceptible tomato cv. Marmande and sometimes also on tobacco cv. NC95 and the pepper cv. Sonar in the case of Meloidogyne arenaria. They did not reproduce on cotton or peanut. The species and new races were identified as M. incognita races 5 (6 populations) and 6 (2 populations) and M. javanica race 5 (2 populations), with new records of M. arenaria race 3 (2 populations) and M. javanica race 1 (23 populations) for Spain.

Effect of soil properties, heavy metals and emerging contaminants in the soil nematodes diversity.

Among soil organisms, nematodes are seen as the most promising candidates for bioindications of soil health. We hypothesized that the soil nematode community structure would differ in three land use areas (agricultural, forest and industrial soils), be modulated by soil parameters (N, P, K, pH, SOM, CaCO3, granulometric fraction, etc.), and strongly affected by high levels of heavy metals (Cd, Pb, Zn, Cr, Ni, Cu, and Hg) and emerging contaminants (pharmaceuticals and personal care products, PPCPs). Although these pollutants did not significantly affect the total number of free-living nematodes, diversity and structure community indices vastly altered. Our data showed that whereas nematodes with r-strategy were tolerant, genera with k-strategy were negatively affected by the selected pollutants. These effects diminished in soils with high levels of heavy metals given their adaptation to the historical pollution in this area, but not to emerging pollutants like PPCPs.

The genus Bursaphelenchus Fuchs (Nematoda: Aphelenchida) in north-west Spain.

As a consequence of the report of pine wood nematode (Bursaphelenchus xylophilus) in the Setubal peninsula (Portugal), nematodes of the genus Bursaphelenchus and the vector insect were studied in pine forests, timber industries and entry points for imported timber in Galicia (north-west Spain). The aim of this paper was to contribute to the establishment of the necessary measures to prevent the introduction of B. xylophilus into Spain. Sampling, nematode extraction and identification were carried out according to the EU norm. From collections made in 1999-2002, a total of 2612 samples were studied. Bursaphelenchus eggersi, B. mucronatus and B. sexdentati were found, as well as Monochamus galloprovincialis, a vector cerambycid beetle. Bursaphelenchus xylophilus was not isolated. Morphometric characteristics and geographic distribution of the species are provided and the risk of introducing B. xylophilus to Spain assessed.

Entomopathogenic nematode food webs in an ancient, mining pollution gradient in Spain.

Mining activities pollute the environment with by-products that cause unpredictable impacts in surrounding areas. Cartagena-La Unión mine (Southeastern-Spain) was active for >2500years. Despite its closure in 1991, high concentrations of metals and waste residues remain in this area. A previous study using nematodes suggested that high lead content diminished soil biodiversity. However, the effects of mine pollution on specific ecosystem services remain unknown. Entomopathogenic nematodes (EPN) play a major role in the biocontrol of insect pests. Because EPNs are widespread throughout the world, we speculated that EPNs would be present in the mined areas, but at increased incidence with distance from the pollution focus. We predicted that the natural enemies of nematodes would follow a similar spatial pattern. We used qPCR techniques to measure abundance of five EPN species, five nematophagous fungi species, two bacterial ectoparasites of EPNs and one group of free-living nematodes that compete for the insect-cadaver. The study comprised 193 soil samples taken from mining sites, natural areas and agricultural fields. The highest concentrations of iron and zinc were detected in the mined area as was previously described for lead, cadmium and nickel. Molecular tools detected very low numbers of EPNs in samples found to be negative by insect-baiting, demonstrating the importance of the approach. EPNs were detected at low numbers in 13% of the localities, without relationship to heavy-metal concentrations. Only Acrobeloides-group nematodes were inversely related to the pollution gradient. Factors associated with agricultural areas explained 98.35% of the biotic variability, including EPN association with agricultural areas. Our study suggests that EPNs have adapted to polluted habitats that might support arthropod hosts. By contrast, the relationship between abundance of Acrobeloides-group and heavy-metal levels, revealed these taxa as especially well suited bio-indicators of soil mining pollution.

Potential Insect Vectors of Bursaphelenchus spp. (Nematoda: Parasitaphelenchidae) in Spanish Pine Forests

Potential insect vectors of Bursaphelenchus xylophilus (PWN) were studied. Pathways of introduction of PWN from Portugal to Europe, through Spain, were determined and traps were located in pine stands sites along the pathways. 19 Cerambycidae, 12 Scolytidae, 12 Buprestidae and 10 Curculionidae species have been found. Trapped insects were examined for the presence of nematodes under their elytra. Nematodes were found on Arhopalus ferus, Spondylis buprestoides, Hylastes ater, Hylurgus lingniperda, Orthotomicus erosus, Pityogenes bidentatus, Tomicus piniperda, Hylobius abietis and Pissodes validirrostris specimens. Monochamus galloprovincialis was the most important insect species, representing a risk for the introduction of the PWN in Spanish pine forests; Cerambycidae and Curculionidae species, were taken into account because they have been reported as vectors of other Bursaphelenchus spp.

Distribution of Xiphinema pyrenaicum Dalmasso, 1969 with notes on X. aceri Chizhov, Tiev & Turkina, 1986 (nematoda: Longidoridae)

A study of the distribution and morphometric characteristics of Xiphinema pyrenaicum and X. aceri was done because of their presence and distribution in Spain. More than 50 populations of X. pyrenaicum were studied and one population of X. aceri, of which the latter included the four juvenile stages not previously described. The study revealed both species to be typical of Mediterranean environments, X. pyrenaicum being widespread in the circum-mediterranean basin.