Phylogenetic relationship between OTU88, OTU38 and top BLAST hits species (with GenBank accession numbers and geographic distribution).

<p>The tree was constructed using the neighbor-joining cluster algorithm. Bootstrap support (%) and posterior probabilities are provided on the branches (BS/PP). Bootstrap values below 50 are not shown. Scale bar, 0.002 substitutions/site.</p

Hierarchically clustered heat map of the taxa distribution with Asian origin.

<p>The relationship among samples was determined by Bray-Curtis distance. The heat map plot depicts the relative percentage of each fungal taxa (variables clustering on the vertical-axis) within each tree host (horizon-axis clustering). The relative abundance for fungal taxa are indicated by color intensity with the legend indicated at the bottom of the figure.</p

Distribution of number of reads within the 106 identified operational taxonomic units (OTUs), singletons excluded.

<p>Distribution of number of reads within the 106 identified operational taxonomic units (OTUs), singletons excluded.</p

Phylogenetic relationship between OTU4 and top BLAST hits species (with GenBank accession numbers and geographic distribution).

<p>The tree was constructed using the neighbor-joining cluster algorithm. Bootstrap support (%) and posterior probabilities are given on the branches (BS/PP). Bootstrap values below 50 are not shown. Scale bar, 0.002 substitutions/site.</p

Planting Sentinel European Trees in Eastern Asia as a Novel Method to Identify Potential Insect Pest Invaders

<div><p>Quarantine measures to prevent insect invasions tend to focus on well-known pests but a large proportion of the recent invaders were not known to cause significant damage in their native range, or were not even known to science before their introduction. A novel method is proposed to detect new potential pests of woody plants in their region of origin before they are introduced to a new continent. Since Asia is currently considered to be the main supplier of insect invaders to Europe, sentinel trees were planted in China during 2007-2011 as an early warning tool to identify the potential for additional Asian insect species to colonize European trees. Seedlings (1-1.5 m tall) of five broadleaved (<i>Quercus petraea</i>, <i>Q</i>. <i>suber</i>, <i>Q</i>. <i>ilex</i>, <i>Fagus sylvatica</i>, and <i>Carpinus betulus</i>) and two conifer species (<i>Abies alba</i> and <i>Cupressus sempervirens</i>) were planted in blocks of 100 seedlings at two widely separated sites (one in a nursery near Beijing and the other in a forest environment near Fuyang in eastern China), and then regularly surveyed for colonization by insects. A total of 104 insect species, mostly defoliators, were observed on these new hosts, and at least six species were capable of larval development. Although a number of the insects observed were probably incidental feeders, 38 species had more than five colonization events, mostly infesting <i>Q</i>. <i>petraea</i>, and could be considered as being capable of switching to European trees if introduced to Europe. Three years was shown to be an appropriate duration for the experiment, since the rate of colonization then tended to plateau. A majority of the identified species appeared to have switched from agricultural crops and fruit trees rather than from forest trees. Although these results are promising, the method is not appropriate for xylophagous pests and other groups developing on larger trees. Apart from the logistical problems, the identification to species level of the specimens collected was a major difficulty. This situation could be improved by the development of molecular databases.</p></div

Comparative colonization of the different species of European trees planted at two sites in China and the frequency of the colonization events.

<p>No. spp > 5 events means that these insect species were observed on more than 5 seedlings during two different years (pooled over both sites). Note that an individual insect species can be observed on more than a single tree species.</p

Foliage damage and damage morphotypes observed by late October 2010 at Beijing and Fuyang.

<p>A: total damage (± standard error; bars headed by the same letter are not significantly different; Kruskall-Wallis test followed by all-pairwise comparisons of mean ranks at α = 0.05); B: relative importance of morphotype damage at Beijing; C: relative importance of morphotype damage at Fuyang. In B and C, several morphotypes can be observed on the same leaf, and summation of the morphotype damage could be higher than total damage. See text for the definition of the morphotypes. The Beijing plot was planted in 2007 and the Fuyang plot in 2008.</p

Numeric importance per family of the insect species that colonized the sentinel trees in China from 2007 to 2011.

<p>Species with more than 5 occurrences were observed on more than 5 seedlings during at least two different years. The Beijing plot was planted in 2007 and the Fuyang plot in 2008.</p

Annual changes in the cumulative number of insect species recruited by European sentinel trees planted in Beijing and Fuyang from 2007 to 2011.

<p>The Beijing plot was planted in 2007 and the Fuyang plot in 2008.</p

Insect species that colonized the European sentinel trees planted in Fuyang and Beijing more than 5 times between 2007 and 2011.

<p>Insect stage: A: Adult; L: larva; P: pupae; E: eggs</p><p>Insect species that colonized the European sentinel trees planted in Fuyang and Beijing more than 5 times between 2007 and 2011.</p