Effect of Monochamus galloprovincialis feeding on Pinus pinaster and Pinus pinea, oleoresin and insect volatiles.

In Portugal, the pine black sawyer Monochamus galloprovincialis is the principal vector of the pinewood nematode, Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD), a lethal phyopathogen with major ecological and economic consequences to European forestry. The aim of this study was to determine the influence of M. galloprovincialis feeding on the volatiles emitted by pine trees. This study focused on the pine species which are most relevant to Portugal, that is, Pinus pinaster (maritime pine) and Pinus pinea (stone or umbrella pine), assessing to what extent pine chemotypes might influence feeding by the insect vector. Preliminary evaluation of each maritime pine essential oil allowed recognizing the existence of two main chemotypes (C1 and C2) and absence of chemical variability in P. pinea. Emission of volatiles from pine trees was evaluated before and during 24 h of feeding by a mixed-sex pair of newly emerged, unfed M. galloprovincialis. Volatiles were also collected from the oleoresin released from the feeding wounds as well as from the insects after feeding. Pine volatiles were collected by solid phase microextraction (SPME) and insect volatiles extracted with pentane, and all analysed by gas chromatography-mass spectrometry (GC-MS) and by GC for component identification and quantification, respectively. Of the seventeen emitted volatiles detected in SPME analyses of P. pinaster, ß-pinene, α-pinene, ß-caryophyllene, and germacrene D showed the highest average fold increases as a result of M. galloprovincialis feeding. When grouped by P. pinaster chemotype, C1 and C2 groups of trees showed different patterns of responses. ß-Caryophyllene and germacrene D showed the highest fold increase in C1 trees, whereas ß-pinene and α-pinene clearly dominated in C2 trees. Likewise, the oleoresin volatiles from C1 trees were dominated by δ-3-carene and/or ß-pinene, whereas α-pinene and ß-pinene were the main volatile components from oleoresin of C2 trees. Nine components were detected in P. pinea volatiles, of which limonene showed the highest fold increase as a result of insect feeding. The volatiles collected from the insects after they had fed on P. pinaster included α-pinene, ß-pinene, and abietic acid, and by the straight-chain n-alkanes n-C27, n-C29, and n-C25, together with the methyl-branched hydrocarbons 3-meC29, 2-meC28, and 3-meC27. A better understanding of the responses of different P. pinaster chemotypes to feeding by M. galloprovincialis may be helpful in the development of new lures to improve pine sawyer trapping in integrated pest management for control of PWD.

Phoretic mite communities associated with bark beetles in the maritime and stone pine forests of Setúbal, Portugal.

The phoretic mite communities of prominent bark beetle pests associated with pine stands of southern Portugal were sampled to determine whether they vary across bark beetle species and stand type. Bark beetles were sampled for mites from two primary (aggressive) bark beetle species (Ips sexdentatus and Orthotomicus erosus) and the most common secondary species (Hylurgus ligniperda) in maritime pine (Pinus pinaster) and stone pine (Pinus pinea) in the Setúbal province of Portugal. Twelve mite species, spanning diverse ecological roles, are found associated with these bark beetle systems. The relative abundances of the 12 species that make up the phoretic mite communities of maritime and stone pine varied significantly between host beetle species as well as between stand type, indicating that the phoretic host and dominant tree type are important drivers of mite community composition. The functional roles of these mites are outlined and their ecological significance in pine forest ecosystems is discussed.

Multi-scale and multi-site resampling of a study area in spatial genetics: implications for flying insect species.

The use of multiple sampling areas in landscape genetic analysis has been recognized as a useful way of generalizing the patterns of environmental effects on organism gene flow. It reduces the variability in inference which can be substantially affected by the scale of the study area and its geographic location. However, empirical landscape genetic studies rarely consider multiple sampling areas due to the sampling effort required. In this study, we explored the effects of environmental features on the gene flow of a flying long-horned beetle (Monochamus galloprovincialis) using a landscape genetics approach. To account for the unknown scale of gene flow and the multiple local confounding effects of evolutionary history and landscape changes on inference, we developed a way of resampling study areas on multiple scales and in multiple locations (sliding windows) in a single large-scale sampling design. Landscape analyses were conducted in 3*104 study areas ranging in scale from 220 to 1,000 km and spread over 132 locations on the Iberian Peninsula. The resampling approach made it possible to identify the features affecting the gene flow of this species but also showed high variability in inference among the scales and the locations tested, independent of the variation in environmental features. This method provides an opportunity to explore the effects of environmental features on organism gene flow on the whole and reach conclusions about general landscape effects on their dispersal, while limiting the sampling effort to a reasonable level.

Efficacy of sulfuryl fluoride against the pinewood nematode, Bursaphelenchus xylophilus (Nematoda: Aphelenchidae), in Pinus pinaster boards.

BACKGROUND: The pinewood nematode (PWN) Bursaphelenchus xylophilus is an important conifer disease worldwide. It is the direct cause of the death of millions of pines in south-east Asia (mainly Japan, China and Korea) and has been established in Portugal since 1999. The phasing out of methyl bromide has created an urgent need for alternative treatment of wood packaging materials. The effect of sulfuryl fluoride (SF), a broad-spectrum fumigant used to control insects, was tested in Pinus pinaster boards naturally infested by PWN. RESULTS: Boards were fumigated for 24 h at three different temperatures (15, 20 and 30 °C) with dosage ranges of 3169-4407, 1901-4051 and 1385-2141 gh m(-3) respectively. Treated wood was sampled for nematode identification and counting, before treatment and after 24 h, 72 h and 21 days. No survival was found in the 15 °C and 30 °C treatments, while at 20 °C the mortality ranged from 94.06 to 100%. Some reasons for the survival at 20 °C are presented. CONCLUSION: Results confirm SF to be an effective quarantine treatment for PWN at 15 and 30 °C. Further studies are needed to obtain the most effective dosage at 20 °C, and to determine the toxicity of SF fumigation on B. xylophilus at other temperatures, especially at 25 °C.