Juan Carlos Iturrondobeitia

Ophiostoma species (Ascomycetes: Ophiostomatales) associated with bark beetles (Coleoptera: Scolytinae) colonizing Pinus radiata in northern Spain

Bark beetles (Coleoptera: Scolytinae) are known to be associated with fungi, especially species of Ophiostoma sensu lato and Ceratocystis. However, very little is known about these fungi in Spain. In this study, we examined the fungi associated with 13 bark beetle species and one weevil (Coleoptera: Entiminae) infesting Pinus radiata in the Basque Country of northern Spain. This study included an examination of 1323 bark beetles or their galleries in P. radiata. Isolations yielded a total of 920 cultures, which included 16 species of Ophiostoma sensu lato or their asexual states. These 16 species included 69 associations between fungi and bark beetles and weevils that have not previously been recorded. The most commonly encountered fungal associates of the bark beetles were Ophiostoma ips, Leptographium guttulatum, Ophiostoma stenoceras, and Ophiostoma piceae. In most cases, the niche of colonization had a significant effect on the abundance and composition of colonizing fungi. This confirms that resource overlap between species is reduced by partial spatial segregation. Interaction between niche and time seldom had a significant effect, which suggests that spatial colonization patterns are rarely flexible throughout timber degradation. The differences in common associates among the bark beetle species could be linked to the different niches that these beetles occupy.

Quantitative Association of Bark Beetles with Pitch Canker Fungus and Effects of Verbenone on Their Semiochemical Communication in Monterey Pine Forests in Northern Spain

Abstract The association between 11 species of bark beetles (Coleoptera: Scolytinae) and one weevil (Coleoptera: Entiminae) with the pitch canker fungus, Fusarium circinatum Nirenberg and O’Donnell, was determined by crushing beetles on selective medium and histone H3 gene sequencing. Pityophthorus pubescens (Marsham) (25.00%), Hylurgops palliatus (Gyllenhal) (11.96%), Ips sexdentatus (Börner) (8.57%), Hypothenemus eruditus Westwood (7.89%), Hylastes attenuatus Erichson (7.40%), and Orthotomicus erosus (Wollaston) (2.73%) were found to carry the inoculum. In addition, the root weevil Brachyderes incanus L. (14.28%) had the second highest frequency of occurrence of the fungus. The responses of the insects to a range of verbenone doses were tested in field bioassays using funnel traps. Catches of P. pubescens, a species colonizing branch tips of live trees, were significantly reduced in a log-linear dose-dependent relationship. Catches of I. sexdentatus, an opportunistic species normally attacking fresh dead host material, were also gradually reduced with increasing verbenone dose. Catches of Tomicus piniperda L., O. erosus, Dryocoetes autographus (Ratzeburg), H. eruditus, Xyleborus dryographus (Ratzeburg), Hylastes ater (Paykull), Hylurgus ligniperda (F.), H. attenuatus, and B. incanus were not significantly affected by verbenone. The effects of verbenone were consistent with differences in host-age preference. Semiochemical disruption by verbenone in P. pubescens and I. sexdentatus could represent an integrated pest management strategy for the prevention of the spread of pitch canker disease between different stands. However, several species associated with F. circinatum were unaffected by verbenone, not supporting this compound for prevention of the establishment of potential vectors in Northern Spain.

Oribatid mite (Acari) community structure in steppic habitats of Burgos Province, central northern Spain

This work is a study of the communities of oribatid mites in steppic areas of Burgos Province, central northern Spain, in relation to different habitat types belonging to natural or disturbed ecosystems. The primary objective was to find the relationship between anthropogenic use of land and several diversity indices. Parameters such as abundance, species richness, real diversity (H′) and equitability (J′) of the mite communities were calculated in 20 soil plots, sampled in spring and autumn 2000, belonging to the predominant habitat types of this area: (1) cultivated lands, (2) abandoned crop lands, (3) grasslands/pastures, and (4) natural oak forests or a pine plantation. The most widespread species in the area as well as the most abundant taxa overall are documented, together with the faunistic checklist of oribatid mites identified in the study. The results show a general decline in the composition of the oribatid community, in terms of species diversity and abundance, from non‐disturbed soils to cultivated lands. The number of species (richness) was usually higher in forest soils than in disturbed ecosystems, in which the most degraded soils showed the lowest number of species. The community analysis shows the differences due to habitat type and ubiquitous bioindicator species.

The ontogeny of morphological traits in three species of Galumnidae (Acari: Oribatida)

The ontogeny of morphological traits in three members of the oribatid mite family Galumnidae – Acrogalumna longipluma (Berlese, 1904), Allogalumna alamellae (Jacot, 1935) and Galumna alata (Hermann, 1804) – is described and illustrated for the first time and compared with the literature. The juveniles of all species have macrosclerites, microsclerites and a humeral organ, but particular species differ in body size, the length of c-series setae, pattern of integument in anterior part of gastronotum and shape of solenidion ω1 on tarsus I. Their larvae additionally differ by the shape of setae in and dp, presence of transverse furrow on the gastronotum and the length of prodorsal seta in, whereas the nymphs differ by the size of circumgenital macrosclerite and presence of adanal macrosclerite. The adults of these species differ mainly by the presence of lamellar ridge L on the prodorsum and location of seta le, shape of porose area Aa, presence of median pore mp on the notogaster and shape of sensillus. The morphology of juveniles of three species of Pilogalumna Grandjean, 1956 suggests that the presence of transverse furrow in larva and absence of circumgenital macrosclerite in nymphs have probably generic value.

Effects of some ecological variables on carabid communities in native and non native forests in the Ibaizabal basin (Basque Country: Spain)

Abstract• Carabid beetles were investigated at five different forest types in the Ibaizabal basin (northern Spain). The landscape is characterized by the presence of remnants of native forest surrounded by conifer plantations.• Carabids were trapped in 52 stands of mixed forest, beech forest, holm oak forest, mixed pine and Monterey pine plantations in 2005 and 2006. The main objectives of the study were: compare carabid diversity, recognise the characteristic species, and study the effects of ecological variables on carabid assemblages in the different forest types.• No significative differences in species abundance, richness and diversity were found among the studied forests. Most of the trapped beetles were identified as forest generalists, nevertheless some native and non-native forest specialist species were also found. Distribution of carabid communities overlapped and, except for beech forest, no specific communities were distinguished. Altitude, percentage of grass coverage and temperature were the main variables influencing species distribution.• The results suggest high habitat homogeneity, caused by regeneration in pine plantations of the indigenous understorey, and by poor habitat quality in native forest (patchy remnants enclosed in conifer plantations). This situation could explain the similar carabid diversity.Résumé• Les carabidés ont été étudiés dans cinq différents types de forêts dans le bassin Ibaizabal (nord de l’Espagne). Le paysage est caractérisé par la présence de vestiges de la forêt naturelle entourés par des plantations de conifères.• Les carabidés ont été piégés en 2005 et 2006, dans 52 peuplements de forêts mixtes, hêtraies, chênaies vertes, peuplement mélangé de pins et plantations de pins de Monterey. Les principaux objectifs de l’étude ont été : la comparaison de la diversité des carabidés, la reconnaissance des espèces caractéristiques, et l’étude des effets des variables écologiques sur les assemblages de carabidés dans les différents types de forêts.• Parmi les forêts étudiées, il n’a pas été mis en évidence de différences significatives pour ce qui concerne l’abondance des espèces, la richesse et la diversité. La plupart des coléoptères piégés ont été identifiés comme étant des généralistes des forêts, néanmoins certaines espèces autochtones et non autochtones des forêts ont également été trouvées. Les répartitions des communautés de carabidés se chevauchent et, à l’exception des hêtraies, aucune communauté spécifique n’a été distinguée. L’altitude, le pourcentage de couverture herbacée et la température ont été les principales variables qui ont influencé la répartition des espèces.• Les résultats obtenus suggèrent que la haute homogénéité de l’habitat est causée par la régénération d’un sous-bois d’espèces naturelles dans les plantations de pins, et par la mauvaise qualité de l’habitat dans la forêt naturelle (restes fragmentaires de forêts entourés par des plantations de conifères). Cette situation pourrait expliquer la diversité similaire des carabidés.

Laboratory and field evaluations of chemical and plant-derived potential repellents against Culicoides biting midges in northern Spain.

The efficacy of 23 compounds in repelling Culicoides biting midges (Diptera: Ceratopogonidae), particularly Culicoides obsoletus (Meigen) females, was determined by means of a Y‐tube olfactometer. The 10 most effective compounds were further evaluated in landing bioassays. The six most promising compounds (including chemical and plant‐derived repellents) were evaluated at 10% and 25% concentrations in field assays using Centers for Disease Control (CDC) light traps. At least three compounds showed promising results against Culicoides biting midges with the methodologies used. Whereas olfactometer assays indicated DEET at 1 µg/µL to be the most effective repellent, filter paper landing bioassays showed plant‐derived oils to be better. Light traps fitted with polyester mesh impregnated with a mixture of octanoic, decanoic and nonanoic fatty acids at 10% and 25% concentrations collected 2.2 and 3.6 times fewer midges than control traps and were as effective as DEET, which is presently considered the reference standard insect repellent. The best plant‐derived product was lemon eucalyptus oil. Although these have been reported as safe potential repellents, the present results indicate DEET and the mixture of organic fatty acids to be superior and longer lasting.

Evidence for (E )-pityol as an aggregation pheromone of Pityophthorus pubescens (Coleoptera: Curculionidae: Scolytinae)

Abstract We present evidence favoring the use of (E)-pityol as an aggregation pheromone in Pityophthorus pubescens (Marsham). (E)-Pityol was detected in effluvia of male and female P. pubescens, and antennae of both sexes responded to (E)-(+)-pityol in electroantennogram assays. In two-choice olfactometer tests, males significantly preferred (E)-(+)-pityol and (E)-(±)-pityol to blank controls at doses of 1, 10, and 100 ng, whereas females only showed a preference for (E)-pityol at the 1 ng dose.

Effects of cattle and industries on oribatid mite communities of grassland soil in the Basque Country (Spain)

The effect of industrial and cattle activities on oribatid mite communities of grassland soil was studied in the Basque Country of Spain. Environmental and community variables were studied in three grassland areas: (1) an industrial site with heavy metal pollution, (2) a cattle farming site with medium and high fertilizer inputs and (3) a natural site – the last one as control. Although the industrial areas presented high concentrations of heavy metals, they showed high biodiversity, perhaps because the metals were bound to the high clay content. Concentrations of Cd, Pb, Cu and Mg at the industrial site were positively correlated with the abundance of Oribatula tibialis, Lauroppia similifallax, Tectocepheus minor, Scheloribates minifimbriatus, Oribatella quadricornuta, Ceratozetes conjunctus and Xenillus tegeocranus. In contrast, the cattle area had poor soils with very low oribatid diversity, which was inversely correlated with the fertilizer input. The high-input cattle grassland had a fewer and less uniformly distributed species compared to the medium-input site. Species positively associated with cattle grasslands are Zygoribatula undulata, Microppia minus minus, Ceratozetes armatus, Peloptulus montanus, Scheloribates latipes and Minunthozetes reticulatus. The natural grasslands had the highest oribatid mite diversity, with species being well distributed.

Disruption of trans‐pityol‐mediated attraction by racemic trans‐conophthorin in twig beetle Pityophthorus pubescens

Twig beetle Pityophthorus pubescens (Coleoptera: Curculionidae: Scolytinae) has been previously associated with the Fusarium circinatum (Hypocreales: Nectriaceae), the pathogen causing pitch canker disease, in P. radiata stands of the Basque Country (Northern Spain). Laboratory and field studies were conducted to evaluate the response of the insect to the racemic mixture of the spiroacetal trans‐7‐methyl‐1,6‐dioxaspiro[4.5]decane, also known as conophthorin. In walking bioassays, addition of 10 and 100 ng of racemic trans‐conophthorin to 1 ng of (±)‐trans‐pityol elicited a negative response in males, whereas females did not show any significant preference. Catches of males in attractant‐baited traps were strongly reduced by racemic trans‐conophthorin at all release rates tested (0.5, 1.0, 1.5 and 2.0 mg/day). In contrast, catches of females were not affected by any of the (±)‐trans‐conophthorin release rate.

Variation in virulence of Beauveria bassiana and B. pseudobassiana to the pine weevil Pissodes nemorensis in relation to mycelium characteristics and virulence genes

Entomopathogenic fungi such as Beauveria spp. have potential applications in the biocontrol of insect pests but little is known regarding their infectivity to the pine weevil Pissodes nemorensis. In this study, five isolates of Beauveria pseudobassiana and five isolates of Beauveria bassiana were tested for characteristics correlating with virulence on P. nemorensis. Isolate UAMH301 had the lowest mean lethal concentration value whereas the highest value was obtained with isolate LRC137. Growth rate was negatively correlated with virulence in B. bassiana, because isolate LRC137, the least virulent isolate, grew much more rapidly than the other B. bassiana isolates on SDYA. In contrast, its growth on a hyperosmotic medium was the slowest. Sporulation rate and conidial area were not correlated with virulence. Mycelial cell density was positively correlated with virulence in both species, and the four tested genes appear to be one-copy genes. Bbchit1 and Bbhog1, genes respectively encoding a chitinase and a protein kinase, induced relative expression levels were positively correlated with virulence in B. pseudobassiana. We discuss in terms of previous morphological, physiological and genetic parameters related to virulence in Beauveria and the importance of testing the expression of putative virulence genes in comparison with their basal transcript levels.