Biodiversity Data Journal :
Research Article
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Corresponding author: Diana Percy (diana.percy@ubc.ca), Quentin Cronk (quentin.cronk@ubc.ca)
Academic editor: Laurence Livermore
Received: 29 Apr 2020 | Accepted: 14 May 2020 | Published: 18 May 2020
© 2020 Diana Percy, Quentin Cronk
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Percy D, Cronk Q (2020) Salix transect of Europe: patterns in the distribution of willow-feeding psyllids (Hemiptera: Psylloidea) from Greece to arctic Norway. Biodiversity Data Journal 8: e53788. https://doi.org/10.3897/BDJ.8.e53788
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Background
Psyllids are oligophagous phytophagous insects with many specialist willow (Salix spp.) feeding species in two genera (Cacopsylla and Bactericera). We examine the patterns of distribution and co-occurrence of willow-feeding species at 42 willow sites across Europe forming a transect from Greece (lat. 38.8 °N) to arctic Norway (lat. 70.6 °N). The transect and sites have been described in previous papers.
New information
A total of 1245 individual psyllids were examined from 23 species of willow over the transect, representing 17 willow-feeding species (11 Cacopsylla and 6 Bactericera). Numerous species were very widely distributed, with two species, Bactericera albiventris (Foerster, 1848) and Cacopsylla pulchra (Zetterstedt, 1840), occurring from Greece to Finland. Other widespread species (Romania to Finland) were Cacopsylla ambigua (Foerster, 1848) and Bactericera curvatinervis (Foerster, 1848). The mean number of psyllid species per site was 2.4 (1.3 Cacopsylla, 1.1 Bactericera).
biogeography, ecospace, Europe, Hemiptera, latitudinal gradient, megatransect, oligophagy, Psyllidae, Salicaceae, Salix feeders, spatial analysis, Triozidae, willow-feeding insects
The megatransect of European lowland willow sites has already been described (
Psyllids, or jumping plant lice, are members of the hemipteran superfamily Psylloidea (
The megatransect used here encompasses a wide variety of climatic conditions. A major transition is between the summer dry Mediterranean and the winter-dry central European plain (Figure 1). At the far north of Fennoscandia extreme winter temperatures prevail (Fig. 2). It is therefore of interest to determine to what extent willow psyllids tolerate widely varying climates in order to achieve wide distributions.
Temperature and water availability are major drivers of psyllid life history variation (
Despite the evidence for critical temperatures in development, psyllids nevertheless seem to be generally tolerant of extreme low temperatures, and absolute low temperatures are rarely implicated in determining psyllid distributions. The Ericaceae-feeding psyllids, Strophingia, are low temperature tolerant at least down to -15°C (
A study of willow psyllids in relation to altitude in Norway found evidence of climatic optima, with Cacopsylla palmeni (Löw, 1882) and C. brunneipennis (Edwards, 1896) at higher and lower altitudes respectively (
Individual species of willow psyllid may oviposit and develop on several related species of willow. For instance, Cacopsylla groenlandica (Šulc, 1913) in Greenland (
Our study, using single season sampling over a large latitudinal range provides a “snap shot” of distribution and abundance at each site with variable climate-host compositions. This lays a baseline that long term repeat sampling can refer to, to assess changes in composition of willows and willow associated insects as the environment of the transect changes. Here we present data for the willow-feeding psyllids to complement data already published for willows and beetles.
The 42 willow sites (Figs
Basic site details and numbers of species of psyllid collected. See
SITE no. |
Country |
Lat. °N |
Long. °E |
Alt (m) |
Date of collection (2015) |
Cacopsylla (no. of spp.) |
Bactericera (no. of spp.) |
Total spp. |
1 |
Greece |
38.80007 |
22.46290 |
37 |
21 April |
1 |
0 |
1 |
2 |
Greece |
38.90200 |
22.31015 |
33 |
21 April |
1 |
1 |
2 |
3 |
Greece |
39.30669 |
22.52832 |
177 |
22 April |
1 |
1 |
2 |
4 |
Greece |
40.03268 |
22.17544 |
534 |
22 April |
2 |
1 |
3 |
5 |
Greece |
41.11332 |
23.27389 |
31 |
23 April |
1 |
1 |
2 |
6 |
Bulgaria |
41.41247 |
23.31861 |
90 |
23 April |
2 |
1 |
3 |
7 |
Bulgaria |
42.16562 |
22.99814 |
392 |
24 April |
2 |
1 |
3 |
8 |
Bulgaria |
42.92399 |
23.81056 |
339 |
24 April |
0 |
1 |
1 |
9 |
Bulgaria |
43.73934 |
23.96675 |
35 |
24 April |
0 |
0 |
0 |
10 |
Romania |
44.26034 |
23.78678 |
81 |
25 April |
1 |
0 |
1 |
11 |
Romania |
44.96198 |
23.19034 |
172 |
25 April |
1 |
1 |
2 |
12 |
Romania |
45.51068 |
22.73722 |
556 |
26 April |
2 |
2 |
4 |
13 |
Romania |
46.51850 |
21.51284 |
102 |
26 April |
1 |
1 |
2 |
14 |
Hungary |
46.70074 |
21.31268 |
94 |
27 April |
1 |
1 |
2 |
15 |
Hungary |
47.66565 |
21.26177 |
91 |
27 April |
3 |
1 |
4 |
16 |
Hungary |
48.37429 |
20.72526 |
148 |
28 April |
0 |
1 |
1 |
17 |
Poland |
49.46345 |
21.69725 |
385 |
28 April |
1 |
2 |
3 |
18 |
Poland |
50.47023 |
22.23837 |
157 |
29 April |
1 |
1 |
2 |
19 |
Poland |
50.67399 |
21.82339 |
141 |
29 April |
2 |
2 |
4 |
20 |
Poland |
51.77504 |
21.19710 |
101 |
30 April |
1 |
2 |
3 |
20a |
Poland |
51.77504 |
21.19710 |
101 |
11 June |
1 |
0 |
1 |
21 |
Poland |
52.69398 |
21.85290 |
96 |
12 June |
1 |
1 |
2 |
22 |
Poland |
53.55483 |
22.30299 |
128 |
12 June |
0 |
1 |
1 |
23 |
Poland |
54.06943 |
23.11745 |
137 |
13 June |
2 |
1 |
3 |
24 |
Lithuania |
54.92583 |
23.77420 |
28 |
13 June |
2 |
0 |
2 |
25 |
Lithuania |
55.79557 |
24.56678 |
62 |
13 June |
1 |
0 |
1 |
26 |
Latvia |
56.71141 |
24.25162 |
23 |
14 June |
3 |
1 |
4 |
27 |
Latvia |
57.74963 |
24.40230 |
7 |
14 June |
3 |
1 |
4 |
28 |
Estonia |
58.42257 |
24.44063 |
18 |
15 June |
4 |
2 |
6 |
29 |
Estonia |
59.40289 |
24.93577 |
48 |
15 June |
2 |
0 |
2 |
30 |
Finland |
60.27299 |
24.65843 |
33 |
16 June |
3 |
1 |
4 |
31 |
Finland |
61.09965 |
25.62820 |
84 |
16 June |
2 |
1 |
3 |
32 |
Finland |
62.04962 |
26.12369 |
174 |
17 June |
2 |
1 |
3 |
33 |
Finland |
63.01589 |
25.80457 |
139 |
17 June |
1 |
2 |
3 |
34 |
Finland |
64.05074 |
25.52664 |
91 |
17 June |
1 |
2 |
3 |
35 |
Finland |
64.61287 |
25.53805 |
58 |
18 June |
2 |
1 |
3 |
36 |
Finland |
65.32835 |
25.29175 |
1 |
18 June |
0 |
1 |
1 |
37 |
Finland |
66.24947 |
23.89450 |
51 |
19 June |
0 |
2 |
2 |
38 |
Finland |
67.21253 |
24.12629 |
160 |
19 June |
0 |
2 |
2 |
39 |
Finland |
67.91183 |
23.63411 |
233 |
19 June |
0 |
2 |
2 |
40 |
Norway |
68.81380 |
23.26658 |
374 |
20 June |
1 |
1 |
2 |
41 |
Norway |
69.72487 |
23.40581 |
289 |
20 June |
1 |
1 |
2 |
42 |
Norway |
70.65234 |
23.66583 |
67 |
21 June |
2 |
0 |
2 |
MEAN |
1.35 |
1.05 |
2.4 |
Southern sites (numbers 1 – 29; Lat. 33.80°N–59.40°N), showing the mean temperature of the driest quarter (scale in °Celsius). This parameter clearly shows the boundary of the hot and dry summer Mediterranean region (green) as opposed to winter-dry central Europe. Bioclimatic parameter (Bio9) extracted from WorldClim.
Specimens in ethanol were subjected to preliminary sorting, followed by clearing of 2 to 5 specimens of each species per site in KOH (10 mins), and subsequent dehydration by alcohol series to return them to 95% ethanol for inspection of cleared material. Cleared specimens were examined under a stereomicroscope at magnifications of up to x50. Species were identified using regional faunas, primarily
Climate variables from WorldClim (
The association between psyllid occurrences and latitude were analysed using canonical correspondence analysis (CCA). The psyllid occurrence matrix (presence and absence of species) was used as the response matrix and latitude as the explanatory matrix. Site 9 (no psyllids) was omitted, as were species found at only one site. For similarity decay with distance (SDD) analyses (
The direct geographical distance from site 1 (Greece) to site 42 (Norway) was 3247 km. Table
Psyllid species (Cacopsylla11 spp.; Bactericera, 6 spp.) collected during this study with distributions (sites and countries). For sites refer to Table 1; country abbreviations: Gr (Greece), Bu (Bulgaria), Ro (Romania), Hu (Hungary), Po (Poland), La (Latvia), Li (Lithuania), Es (Estonia), Fi (Finland), No (Norway). Median site: the central tendency of the species distribution is given as site median (low numbers indicate southern species, high numbers indicate northern species), and on the basis of the site distribution, species are classified as southern (S), middle (M), northern (N) or wide (W).
Sp. no. |
Species |
Site numbers |
Countries |
No. of sites (tot.) |
Number of individuals (total) |
Median site |
1 |
Cacopsylla saliceti (Foerster, 1848) |
2 – 7, 10 – 15, 19, 20, 20a, 21, 24 |
Gr, Bu, Ro, Hu, Po, Li |
17 |
224 |
12 (S) |
2 |
Cacopsylla moscovita (Andrianova, 1948) |
23, 27, 28 |
Po, La, Es |
3 |
22 |
27 (M) |
3 |
Cacopsylla propinqua (Schaefer, 1949) |
42 |
No |
1 |
38 |
42 (N) |
4 |
Cacopsylla sp. [S6H6] |
6 |
Bu |
1 |
2 |
6 (S) |
5 |
Cacopsylla pulchra (Zetterstedt, 1840) |
1, 4, 7, 15, 18, 19, 25 – 31 |
Gr, Bu, Hu, Po, Li, La, Es, Fi |
13 |
>198 |
25 (W) |
6 |
Cacopsylla sp. [S17H2] |
17 |
Po |
1 |
1 |
17 (M) |
7 |
Cacopsylla brunneipennis (Edwards, 1896) |
15, 30 – 32, 34, 35, 42 |
Hu, Fi, No |
7 |
274 |
32 (N) |
8 |
Cacopsylla zaicevi (Šulc, 1915) |
41 |
No |
1 |
6 |
41 (N) |
9 |
Cacopsylla ambigua (Foerster, 1848) |
12, 23, 26, 28, 30, 32, 33, 35 |
Ro, Po, La, Es, Fi |
8 |
118 |
29 (W) |
10 |
Cacopsylla abdominalis (Meyer-Dür, 1871) |
24, 26 – 29 |
Li, La, Es |
5 |
32 |
27 (M) |
11 |
Cacopsylla nigrita (Zetterstedt, 1828) |
40 |
No |
1 |
2 |
40 (N) |
12 |
Bactericera striola Ossiannilsson, 1992 |
27, 30 – 38 |
La, Fi |
10 |
73 |
33.5 (N) |
13 |
Bactericera curvatinervis (Foerster, 1848) |
12, 17 – 20, 23, 28, 39 |
Ro, Po, Es, Fi |
8 |
26 |
19.5 (W) |
14 |
Bactericera cf. parastriola Conci, Ossiannilsson & Tamanini, 1988 |
37 – 41 |
Fi, No |
5 |
96 |
39 (N) |
15 |
Bactericera sp. [S21H4] |
21 |
Po |
1 |
4 |
21 (M) |
16 |
Bactericera salicivora (Reuter, 1876) |
33 |
Fi |
1 |
1 |
33 (N) |
17 |
Bactericera albiventris (Foerster, 1848) |
2 – 8, 11 – 17, 19, 20, 22, 26, 28, 34 |
Gr, Bu, Ro, Hu, Po, La, Es, Fi |
20 |
128 |
13.5 (W) |
Four species occurred in 10 or more sites: Cacopsylla saliceti (Foerster, 1848) (17 sites: mainly southern), Cacopsylla pulchra (Zetterstedt, 1840)(13 sites: widespread), Bactericera striola (Flor, 1861) (10 sites: throughout Finland) and Bactericera albiventris (Foerster, 1848) (20 sites: widespread). The species with the widest geographical distribution were B. albiventris and C. pulchra, both occurring from Greece to Finland. Fig.
Comparison of the climates at the northernmost and southernmost localities for Bactericera albiventris. Hythergraph showing mean monthly temperature and precipitation (see methods for details). The climate track for the Finnish site shows the winter-dry, summer-wet climate, whereas the climate track for the Greek site shows the winter-wet, summer-dry climate characteristic of the Mediterranean. Collection months are arrowed.
Other widespread species (Romania to Finland) were Cacopsylla ambigua (Foerster, 1848) and Bactericera curvatinervis (Foerster, 1848). Three taxa, found only at single sites, remain unidentified: Cacopsylla sp. [S6H6] (site 6, Bulgaria), Cacopsylla sp. [S17H2] (site 17, Poland), Bactericera sp. [S21H4] (site 21, Poland). These are likely described species with insufficient material to determine, but may represent undescribed species. Cacopsylla brunneipennis appears to be a new record for Hungary and is not included in
Species |
Europe only |
Europe and other palaearctic |
Europe, other palaearctic, nearctic |
In transect |
Bactericera albiventris (Foerster, 1848) |
* |
* |
||
Bactericera curvatinervis (Foerster, 1848) |
* |
* |
||
Bactericera maura (Foerster, 1848) |
* |
|||
Bactericera parastriola Conci, Ossiannilsson & Tamanini, 1988 |
* |
* |
||
Bactericera salicivora (Reuter, 1876) |
* |
* |
||
Bactericera salictaria (Loginova, 1964) |
* |
|||
Bactericera silvarnis (Hodkinson, 1974) |
* |
|||
Bactericera striola (Flor, 1861) |
* |
* |
||
Bactericera substriola Ossiannilsson, 1992 |
* |
|||
Bactericera versicolor (Löw, 1888) |
* |
|||
Cacopsylla abdominalis (Meyer-Dür, 1871) |
* |
* |
||
Cacopsylla ambigua (Foerster, 1848) |
* |
* |
||
Cacopsylla atlantica (Loginova, 1976) |
* |
|||
Cacopsylla brunneipennis (Edwards, 1896) |
* |
* |
||
Cacopsylla elegantula (Zetterstedt, 1840) |
* |
|||
Cacopsylla flori (Puton, 1871) |
* |
|||
Cacopsylla intermedia (Löw, 1888) |
* |
|||
Cacopsylla iteophila (Löw, 1876) |
* |
|||
Cacopsylla moscovita (Andrianova, 1948) |
* |
* |
||
Cacopsylla nigrita (Zetterstedt, 1828) |
* |
* |
||
Cacopsylla palmeni (Löw, 1882) |
* |
|||
Cacopsylla parvipennis (Löw, 1877) |
* |
|||
Cacopsylla perrieri Lauterer & Burckhardt, 1997 |
* |
|||
Cacopsylla propinqua (Schaefer, 1949) |
* |
* |
||
Cacopsylla pulchra (Zetterstedt, 1840) |
* |
* |
||
Cacopsylla saliceti (Foerster, 1848) |
* |
* |
||
Cacopsylla tatrica Lauterer & Burckhardt, 1994 |
* |
|||
Cacopsylla zaicevi (Šulc, 1915) |
* |
* |
||
Total |
7 |
18 |
3 |
14 |
The canonical correspondence analysis (CCA) gave a single canonical axis reflecting the variation in the data matrix that is best explained by latitude. The canonical axis (latitude) explains 19.15% of the variation, while the first non-canonical axis explains 21.16%. When the first canonical axis is then compared with latitude (Fig.
Comparison of site latitude with site scores on the latitude-constrained CCA axis. Correlation between the two would indicate that species composition at sites is strongly associated with latitude. The southern sites show no strong latitudinal pattern (sites 1-22: R² = 0.0165) whereas northern sites do (sites 23-42: R² = 0.756).
Multiple psyllids were found on most of the willow species (Table
Classification of psyllid-hosting willows on the transect, with the number of psyllid species recorded in this study, and the number of sites at which the willows were found. The willow classification is taken from
Salix |
No. of psyllid species |
No. of sites |
Salix subgenus |
Salix section |
S. glauca |
4 |
5 |
Chamaetia |
Glaucae |
S. triandra |
4 |
15 |
Salix |
Amygdalinae |
S. triandra x viminalis |
2 |
3 |
Salix |
Amygdalinae/ Vimen |
S. alba |
3 |
20 |
Salix |
Salix |
S. euxina |
1 |
4 |
Salix |
Salix |
S. x fragilis |
7 |
13 |
Salix |
Salix |
S. phylicifolia |
7 |
14 |
Vetrix |
Arbuscella |
S. hastata |
3 |
5 |
Vetrix |
Hastatae |
S. amplexicaulis |
1 |
4 |
Vetrix |
Helix |
S. purpurea |
4 |
8 |
Vetrix |
Helix |
S. purpurea x viminalis |
3 |
8 |
Vetrix |
Helix/Vimen |
S. myrsinifolia |
7 |
13 |
Vetrix |
Nigricantes |
S. aurita |
3 |
6 |
Vetrix |
Vetrix |
S. bebbiana (S. starkeana) |
4 |
7 |
Vetrix |
Vetrix |
S. caprea |
4 |
14 |
Vetrix |
Vetrix |
S. cinerea |
4 |
9 |
Vetrix |
Vetrix |
S. cinerea x aurita |
4 |
1 |
Vetrix |
Vetrix |
S. silesiaca |
2 |
1 |
Vetrix |
Vetrix |
S. lapponum |
3 |
4 |
Vetrix |
Villosae |
S. gmelinii |
1 |
1 |
Vetrix |
Vimen |
S. viminalis |
7 |
9 |
Vetrix |
Vimen |
Host associations of psyllids occurring at five or more sites. The host association index is calculated as consistency of association (the number of sites where a psyllid occurs on a particular willow as a percentage of total sites for that psyllid) multiplied by strength of association (the percentage of individuals, from all sites, recorded from that willow). When a psyllid is recorded very occasionally on a particular willow (host association index <1), or the total number of insects for that willow is <5, the association is merely recorded as +. The strongest associations between a psyllid species and a particular willow are marked in bold. In rare cases where host association could be confirmed by immature identifications, this is marked by a double asterisk (**, multiple sites) or single asterisk (*, single site).
Salix |
C. pulchra |
B. albi-ventris |
C. saliceti |
B. striola |
B. curvati-nervis |
C. ambig-ua |
C. brunnei-pennis |
B. cf. para-striola |
C. abdom-inalis |
S. glauca |
- |
- |
- |
- |
- |
- |
- |
+ |
- |
S. triandra |
+ |
2.4 |
+ |
- |
- |
1.3 |
- |
- |
- |
S. triandra x viminalis |
- |
+ |
+ |
- |
- |
- |
- |
- |
- |
S. alba |
- |
27.1 |
25.5 |
- |
- |
- |
- |
- |
- |
S. euxina |
- |
+ |
- |
- |
- |
- |
- |
- |
- |
S. x fragilis |
+ |
7.8 |
2.4 |
- |
- |
- |
- |
- |
+ |
S. phylicifolia |
+ |
+ |
- |
61.4 |
- |
+ |
14.0** |
28.3 |
- |
S. hastata |
- |
- |
- |
+ |
+ |
- |
- |
1.4 |
- |
S. amplexicaulis |
+ |
- |
- |
- |
- |
- |
- |
- |
- |
S. purpurea |
5.7 |
- |
+ |
- |
+ |
- |
- |
- |
- |
S. purpurea x viminalis |
+ |
+ |
- |
- |
- |
- |
- |
- |
+ |
S. myrsinifolia |
5.8 |
- |
- |
4.4 |
- |
1.1 |
4.0* |
- |
6.5 |
S. aurita |
+ |
- |
- |
- |
2.9 |
+ |
- |
- |
- |
S. bebbiana |
+ |
- |
- |
- |
+ |
2.2 |
- |
- |
- |
S. caprea |
+ |
- |
- |
- |
- |
3.7 |
+ |
- |
- |
S. cinerea |
3.5 |
+ |
- |
- |
+ |
- |
3.4** |
- |
- |
S. cinerea x aurita |
1.6 |
- |
- |
- |
+ |
+ |
- |
- |
- |
S. silesiaca |
- |
- |
- |
- |
+ |
1.5* |
- |
- |
- |
S. lapponum |
- |
- |
- |
- |
- |
- |
- |
1.8 |
- |
S. gmelinii |
- |
- |
+ |
- |
- |
- |
- |
- |
- |
S. viminalis |
+ |
+ |
3.4 |
- |
8.7 |
- |
- |
- |
8.6 |
Of the rarer psyllids (<5 sites) the host occurrences were as follows: Bactericera salicivora (Reuter, 1876) (S. myrsinifolia), Bactericera sp. [S21H4] (S. viminalis, S. x fragilis), Cacopsylla moscovita (Andrianova, 1948) (S. viminalis, S. x fragilis, S. myrsinifolia, S. cinerea x S. aurita, S. caprea, S. bebbiana), Cacopsylla nigrita (Zetterstedt, 1828)(S. phylicifolia, S. glauca), Cacopsylla propinqua (Schaefer, 1949)(S. glauca, S. gmelinii), Cacopsylla sp. [S17H2] (S. purpurea), Cacopsylla sp. [S6H6] (S. alba, S. x fragilis), Cacopsylla zaicevi (Šulc, 1915) (S. glauca, S. hastata). These less common psyllids were generally collected on one or two willow species only. An exception was C. moscovita, which although found only at three sites, these sites were willow-rich and C. moscovita was found widely on the willow species present.
There is some indication of a Salix taxonomic signal in the host preferences of psyllids. For instance, Bactericera albiventris is found commonly on S. triandra, S. alba, S. x fragilis (all subgenus Salix) and rarely on other willows (subgenus Vetrix). In contrast, Cacopsylla pulchra is found commonly on S. purpurea, S. myrsinifolia, S. cinerea, S. cinerea x aurita (all subgenus Vetrix) and rarely on subgenus Salix. However, there is no indication of a systematic difference between Bactericera and Cacopsylla in host choice, as species of both genera occur widely on a variety of hosts.
We used similarity decay with distance (SDD) analysis (
Parameters taken from the graphs in Figure 6, showing overall similarity in gross faunistic/floristic patterning between willows and psyllids.
Willows |
Psyllids |
||
local similarity |
S(km=0) |
0.3203 |
0.3897 |
local diversity |
1- S(km=0) |
0.6797 |
0.6103 |
similarity decay distance |
km(S=0) |
2502km |
2633km |
slope |
0.000128 |
0.000148 |
Similarity decay with distance (SDD) analysis. Plot of decreasing site similarity (Jaccard similarity coefficient, based on: A = willows; B = psyllids) with geographical distance (km). The red trendline shows the linear regression. The patterns show similar gross geographical patterning between willows and psyllids.
It is clear from previous studies of psyllid biology that there is tight ecological integration between individual psyllid species and their hosts, for instance in phenological synchronicity, and in feeding choice using particular elements of willow morphological space such as catkins (
We show that the psyllid fauna varies across Europe, but largely in response to increasing boreality in the north. The enormous climatic difference between the Mediterranean region and the central European plain seems (from our data) to make little difference to the psyllid fauna.
We also provide evidence that there is broad-scale patterning of host use, particularly with regard to subgenus Salix vs subgenus Vetrix. Although individual psyllid species are clearly able to utilize numerous related willow hosts depending on what species are available, there does seem to be a distinct division between Vetrix specialists and Salix specialists. Willows are taxonomically complex with many recorded hybrids (
This study provides a baseline to use in future analyses of geographical shifts and responses to climate. In addition, sampling more (both temporally and geographically) sites and habitats will undoubtedly yield more diversity (e.g. psyllids on alpine willows).
Despite the obvious limitations of a rapid survey megatransect approach, there are increasingly sophisticated ecological meta-analysis approaches that provide opportunities to combine large and local scale surveys at independent data scales in order to address big science questions (e.g.
A rapid survey transect of the willow-feeding psyllids of Europe has provided a "snapshot" of the diversity of salicivorous psyllids on a continental scale. At 42 sites across Europe along a latitudinal gradient, we collected 1245 psyllids from 23 species of willow, representing 17 willow-feeding species (11 Cacopsylla and 6 Bactericera). Patterns of distribution and host association were evident. Numerous species were very widely distributed, with two species, Bactericera albiventris (Foerster, 1848) and Cacopsylla pulchra (Zetterstedt, 1840), occurring from Greece to Finland.
Funding for the fieldwork was partly provided by the Natural History Museum (London, UK) Life Sciences Departmental Investment Fund (SDF13010) to DMP. We thank Gavin Broad (NHM) and Enrico Ruzzier (University of Padova) for advice and expert help in the field. We thank Ian Hodkinson and Daniel Burckhardt for valuable reviewers comments.
DP planned and directed the work, obtained funding for the study, collected, identified and analyzed the psyllids and co-wrote the paper; QC assisted collection; contributed the planning of the work, analyzed the data and co-wrote the paper.