Biodiversity Data Journal 9: e66112 CO)
doi: 10.3897/BDJ.9.e66112 open access
Research Article

The spread of Colletes hederae Schmidt &
Westrich, 1993 continues - first records of this
plasterer bee species from Slovakia and

the Czech Republic

Petr Boguscht, Jozef Luka8§, Martin Slachta!, Jakub Straka", Peter Sima*, Jan Erhart®,
Antonin Pridal*

$ Univerzita Hradec Kralove, Faculty of Science, Department of Biology, Rokitanského 62, Hradec Kralove, Czech Republic

§ Sutazna 10, Bratislava, Slovakia

| Global Change Research Institute of the Czech Academy of Sciences, Lipova 1789/9, , Ceské Budéjovice, Czech Republic

4] Charles University in Prague, Faculty of Science, Department of Zoology, Viniéna 7, Prague, Czech Republic

# Koppert s.r.o., Komarnanska cesta 13, Nové Zamky, Slovakia

x Institute of Parasitology, Biological Centre CAS, BraniSovska 31, Ceské Bud@jovice, Czech Republic

« Mendel University in Brno, Faculty of AgriSciences, Department of Zoology, Fishery, Hydrobiology and Apidology,
zemédélska 1, Brno, Czech Republic

Corresponding author: Antonin Pridal (pridal@apridal.cz)
Academic editor: Dominique Zimmermann
Received: 18 Mar 2021 | Accepted: 09 Apr 2021 | Published: 23 Apr 2021

Citation: Bogusch P, Luka’ J, Slachta M, Straka J, Sima P, Erhart J, Pridal A (2021) The spread of Colletes
hederae Schmidt & Westrich, 1993 continues — first records of this plasterer bee species from Slovakia and the
Czech Republic. Biodiversity Data Journal 9: e66112. https://doi.org/10.3897/BDJ.9.e66112

Abstract

Colletes hederae Schmidt & Westrich, 1993 is a cryptic bee species from the C. succinctus
species-group. The previous occurrence and spreading of this species were predominantly
in south-western Europe. To determine if the species was spreading in Slovak territory,
Hedera helix was monitored from autumn 2015. The ivy-bee was first recorded in Slovakia
during autumn 2017. This species is widespread inside and around Bratislava; however, it
was not recorded under this study in any sites located eastwards. In the Czech Republic, it
was not recorded in the south-east part of the country in 2017-2019. In 2020, the
occurrence of this species was confirmed in many localities in the south of the country and
strong populations were discovered, especially in the towns Znojmo and Mikulov. The

© Bogusch P etal. 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.

2 Bogusch P et al

populations likely originated from neighbouring Austria, where this species was discovered
in 2006 and the localities are usually less than 100 km away from Czech and Slovak
localities. A further survey could map a route of the northwards spread of this species.

Keywords

Apoidea, Colletidae, ivy-bee, species occurrence, Hedera helix

Introduction

Colletes hederae Schmidt & Westrich, 1993 is a cryptic species from the C. succinctus
species-group with minute morphological differences useful for its identification (Amiet et
al. 1999, Kuhlmann et al. 2007); thus, the species was described recently according to type
material from north-western Croatia (Istria), north and central Italy, south-western Germany
and south-eastern France (Schmidt and Westrich 1993). Currently, the rapid spread of this
species has been recorded in Europe (Hopfenmuler 2014). The discovery of this plasterer
bee species was, on the one hand, facilitated by its plant preference for ivy (Hedera helix)
(Schmidt and Westrich 1993) and, on the other hand, impeded by confusing it with C.
succinctus (Linnaeus, 1758) (Amiet et al. 1999) or C. halophilus Verhoeff, 1944 (Amiet et
al. 1999, Kuhlmann et al. 2007, Zenz et al. 2021). The progress in the spread of the
species after its discovery can be assumed from individual faunistic studies (Wiering 1999,
Cross 2002, Ortiz-Sanchez 2009, Standfuss 2009, Roberts and Vereecken 2010, Teppner
et al. 2009, Burger 2010, Voigt and Szalai-Dobosné 2019, Saure et al. 2019, Saure 2020),
as it is obvious also from the distribution maps created by Kuhlmann et al. (2007) or
Vereecken et al. (2009). The current species distribution is as follows: Austria, Belgium,
Bosnia, Croatia, France, Germany, Greece, Italy, Montenegro, Netherlands, Serbia,
Slovenia, Spain, UK and Channel Islands (all summarised by Kuhlmann et al. 2007),
Switzerland (Amiet et al. 1999), Russia: Crimea (Proshchalykin et al. 2017) and Hungary
(Voigt and Szalai-Dobosné 2019). Interestingly, the spread likely travels in two directions —
the species is enlarging its area to the northwest (from southern to towards the UK in the
north-west (Vereecken et al. 2006, Vereecken et al. 2009)) and to the east in the south
Europe (from Italy and Croatia to Serbia, Greece, Bosnia and Crimea) (Jacobi et al. 2015,
Zettel and Wiesbauer 2014).

The reasons for which the species enlarges its distribution area are not well understood.
Several indications are pointing to the impact of the unusually high temperatures at the turn
of summer and autumn resulting from global climatic change (Frommer 2010, HopfenmUler
2014). Teppner et al. (2009) and Frommer (2010) observed that C. hederae creates only a
local settlement “with larger distribution gaps” during its immigration and only a subsequent
mass spread closes these gaps. Similar experiences were noted by Zettel and Wiesbauer
(2014) in Lower Austria.

There are exceptions from the above mentioned northwesterly direction of the species as
follows: the northern direction in Austria and Hungary (Teppner et al. 2009, Voigt and

The spread of Colletes hederae Schmidt & Westrich, 1993 continues — f ... 3

Szalai-Dobosné 2019) eastern directions recorded in Greece (Standfuss 2009) and on the
Crimea Peninsula (Proshchalykin et al. 2017). With regard to these faunistic records and
expected eastwards expansion (Vereecken et al. 2009), we observed bees on ivy (H. helix)
in many localities situated in the southern part of Slovakia from the season in 2015 and in
the south of Moravia (eastern part of the Czech Republic according to Bogusch et al. 2007)
from the season in 2017. Additionally, we tried to discover this species in the south of
Bohemia (western part of the Czech Republic according to Bogusch et al. (2007)) in 2020.
This contribution aims to report the first recorded occurrence of C. hederae in Slovakia in
the year 2017 and the Czech Republic in the year 2020.

Material and methods

Hedera helix was observed within the blooming period (August to October) due to the
expected spreading of C. hederae to Slovakia from autumn 2015. These observations
were carried out in urban areas and always in places with a connection to gardens (hedge,
overgrown fence, small garden building) or parks. Cemetery walls were also frequently
studied localities. Altogether, we observed flower visitors on the ivy at 42 localities in
Slovakia between the years 2015-2020 (Tables 1, 2).

Table 1.

Records of Colletes hederae.

(N/E = northern latitude/eastern longitude; Lgt. = recorded by; M/F = male/female)

Country Town (Locality) Coordinates Lgt. Date Sex
(N/E) (M/F)

CZ Bynov (way to Bynovsky pond) 48.8187°/ M. Slachta 23- 5/0
14.7998° 24.09.2020

CZ Nové Hrady (Vitorazska) 48.7902°/ M. Slachta 1—4.10.2020 0/4
14.7837°

CZ Brno (central cemetery) 49.1680°/ A. Pridal 22.09.2020 1/2
16.5939°

CZ Brno (Kravi Hora) 49.2056°/ A. Pridal 22.09.2020 2/0
16.5805°

CZ Brno (Spilberk) 49.1933°/ A. Pridal 23.09.2020 0/2
16.6042°

CZ Brno (Zluty kopec) 49.1940°/ A. Pridal 23.09.2020 1/0
16.5915°

CZ Breclav (cemetery wall) 48.7526°/ P. 15.09.2020 3/0
16.8669° Bogusch

CZ Dolni Dunajovice (cemetery wall) 48.8523°/ P. 14.09.2020 3/2
16.5982° Bogusch

CZ Hodonin (Velkomoravska) 48.8516°/ P. 15.09.2020 2/0

17.0975° Bogusch

Bogusch P et al

Country Town (Locality)

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

SK

SK

SK

SK

SK

SK

SK

SK

SK

SK

SK

Kostice (Namésti osvobozeni)

Mikulov (around cemeteries)

Mikulov (Castle)

Mikulov (Dietrichstein chamber)

Mikulov (Kamenny fadek)

Mikulov (Novokopeéna)

Vranovice (near the square)

Znojmo (administration center)

Znojmo (Dyjska)

Znojmo (under the terraces)

Bratislava (Devi/Hadia cesta)

Bratislava (Devi/Hradna)

Bratislava (Devi/Slovanské nabrezie)

Bratislava (Karlova Ves, LiS¢ie Udolie)

Bratislava (Kralovske udolie)

Bratislava (Nové Mésto, Brectanova)

Bratislava (Nové Mésto, Racianska)

Bratislava (Nové Mésto, way to Kamzik)

Bratislava (Ondrejsky cemetery)

Bratislava (Palisady)

Bratislava (Ra¢a, Potoéna)

Coordinates

(N/E)

48.7469°/
16.9815°

48.8104°/
16.6381°

48.8065°/
16.6365°

48.8064°/
16.6399°

48.8072°/
16.6416°

48.8043°/
16.6409°

48.9678°/
16.6062°

48.8586°/
16.0444°

48.8510°/
16.0496°

48.8532°/
16.0455°

48.1636°/
17.1023°

48.1929°/
16.9759°

48.1737°/
16.9843°

48.1525°/
17.0636°

48.1414°/
17.0941°

48.1742°/
17.1023°

48.1709°/
17.1024°

48.1838°/
17.1313°

48.1484°/
17.1226°

48.1478°/
17.1003°

48.2172°/
17.1503°

Lgt.

P.
Bogusch

P.
Bogusch

P.
Bogusch

P.
Bogusch

P.
Bogusch

P.
Bogusch

P.
Bogusch

P.
Bogusch

P.
Bogusch

P.

Bogusch
J. Lukas
J. Lukas
J. Lukas
J. Lukas
J. Lukas
J. Lukas
J. Lukas
J. Lukas
J. Lukas

M. Wiezik

J. Lukas

Date

15.09.2020

15.09.2020

15.09.2020

15.09.2020

15.09.2020

15.09.2020

15.09.2020

14.09.2020

14.09.2020

14.09.2020

05.09.2019

21.09.2018

21.09.2018

20.09.2018

21.09.2018

26.09.2019

19.09.2018

18.09.2018

16.09.2020

18.09.2020

29.09.2017

Sex
(M/F)
3/0
>10/
>10

>10/
>10

>10/
>10

>10/
>10

>10/

>10

2/0

>10/

>10

3/8

8/>10

0/1

0/1

0/1

1/12

>10/1

0/3

1/1

0/1

0/1

0/2

0/1

The spread of Colletes hederae Schmidt & Westrich, 1993 continues — f ...

Country Town (Locality) Coordinates Lgt. Date Sex
(N/E) (M/F)

SK Bratislava (Staré Mésto, Fialkove udolie) 48.1446°/ J. Luka$ 21.09.2018 1/1
17.0930°

SK Bratislava (Staré Mésto, MikulaSsky 48.1427°/ J. Lukas 18.09.2019 1/2

cemetery) 17.0900°

SK Bratislava (Staré Mésto, Mudrofova) 48.1453°/ J. Lukas 27.09.2018 0/1
17.0939°

SK Bratislava (Vrakuna cemetery) 48.1428°/ J. Lukas 16.09.2020 0/2
17.1914°

SK Devinska Nova Ves (6. Aprila square) 48.2074°/ J. Lukas 21.09.2018 1
16.9721°

SK Devinska Nova Ves (near Sandberg) 48.2008°/ J. Straka = 31.08.2017 4/0
16.9739°

SK Devinska Nova Ves (near Sandberg) 48.2008°/ P. 05.09.2017 6/3
16.9739° Bogusch

SK Devinska Nova Ves (Waitov quarry) 48.1797°/ J. Lukas 21.09.2018 0/1
16.9804°

SK Ivanka pri Dunaji (Potocka) 48.1882°/ J. Lukas 16.09.2020 0/2
17.2628°

SK Jarovce (cemetery wall) 48.0639°/ J. Lukas 15.09.2020 2/1
17.1159°

SK Limbach (Sportova) 48.1712°/ J. Lukas 29.09.2019 0/2
16.9844°

SK Pezinok (Grinava, Sturova) 48.2705°/ J. Lukas 29.09.2019 0/2
17.2476°

SK Rusovce (cemetery wall) 48.0522°/ J. Lukas 15.09.2020 4/1
17.1439°

A Hainburg (cemetery wall) 48.1461°/ J. Lukas 30.09.2018 0/1
16.9490°

H Rajka (cemetery wall) 47.9976°/ J. Lukas 23.09.2019 0/1
17.1950°

Table 2.

Locations without recorded occurrence of Colletes hederae.

(N/E = northern latitude/eastern longitude; Obs. = observed by)

Country Town Locality Coordinates Observed Date
(N/E)

CZ Ceské Budéjovice E. RoSsického Street 48.9893°/ J. Erhart 23.09.2020
14.4362°

CZ Ceské Budéjovice Lipova Street 48.9778°/ J. Erhart 23.09.2020
14.4559°

CZ Ceské Budéjovice near football ground 48.9823°/ J. Erhart 23.09.2020

14.4475°

Country Town

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

CZ

Ceské Budéjovice

Ceské Budéjovice

Hradec Kralove

Jiterni Ves

Kali8té u Lipi

Lipnice nad

Sazavou

Mokré

Nové Hrady

Nové Hrady

Rzy

Vysoké Myto

Brno

Brno

Brno

Brno

Brno

Brno

Brno

Brno

Hodonin

Lukov

Bogusch P et al

Locality

Plzenska

V Oblouku

terraces

at crossroad

centre

near the square

margin

at pond Sedlakovec

Vallon Cheri apartments

main road
Cerna Pole, Botanical
Garden

Novy Liskovec
Novy Liskovec
Novy Liskovec
Stranice
Stranice
Spilberk
Spilberk

Na Vyhoné

Novy Hradek

Coordinates

(N/E)

48.9895°/
14.4631°

48.9908°/
14.4614°

50.2087°/
15.8293°

48.8881°/
14.7590°

48.9563°/
14.3808°

49.6132°/
15.4106°

48.9649°/
14.4108°

48.7907°/
14.7836°

48.7900°/
14.7757°

50.0040°/
16.1205°

49.9522°/
16.1563°

49.2131°/
16.6150°

49.1809°/
16.5629°

49.1786°/
16.5624°

49.1806°/
16.5585°

49.2070°/
16.5802°

49.2059°/
16.5798°

49.1972°/
16.5947°

49.1963°/
16.5962°

48.8628°/
17.1352°

48.8372°/
15.9059°

Observed
J. Erhart
J. Erhart
P.
Bogusch
M. Slachta
J. Erhart
P.
Bogusch
J. Erhart
M. Slachta
M. Slachta
P

Bogusch
P

Boglisch
A. Pridal
A. Pridal
A. Pridal
A. Pridal
A. Pridal
A. Pridal
A. Pridal
A. Pridal
P.

Bogusch

P.
Bogusch

Date

23.09.2020

23.09.2020

22.09.2020

23.09.2020

23.09.2020

03.10.2020

23.09.2020

23.09.2020

23.09.2020

27.09.2020

22.09.2020

23.09.2020

24.08.—

27.09.2020

24.08.—
27.09.2020

24.08.—

27.09.2020

22.09.2020

22.09.2020

23.09.2020

23.09.2020

15.09.2020

15.09.2020

The spread of Colletes hederae Schmidt & Westrich, 1993 continues — f ... 7

Country Town Locality Coordinates Observed Date
(N/E)

CZ Znojmo Granické Valley 48.8553°/ P. 14.09.2020
16.0406° Bogusch

SK Andovce Novozamecka 47.9950°/ P. Sima 2017-2020
18.1042°

SK Banov 48.0487°/ P. Sima 03.10.2020
18.1915°

SK Banska Stiavnica Starozamocka 48.4601 °/ P. Sima 2017-2020
18.8915°

SK Bela 47.8319°/ P. Sima 2017-2020
18.5973°

SK Beladice Pusty Chotar 48.3417°/ P. Sima 10.10.2020
18.2796°

SK Chlaba 47.8295°/ P. Sima 2017-2020
18.8273°

SK Imefl 47.9020°/ P. Sima 03.10.2020
18.1413°

SK Komarno 47.7574°/ P. Sima 2017-2020
18.1298°

SK Komoéa 47.9500°/ P. Sima 03.10.2020
18.0232°

SK Levice 48.2163°/ P. Sima 2017-2020
18.6000°

SK Nesvady 47.9267°/ P. Sima 03.10.2020
18.1217°

SK Nitra 48.3129°/ P. Sima 2017-2020
18.0894°

SK Nové Zamky 47.9861°/ P. Sima 2017-2020
18.1631°

SK Ondrejovce 48.1376°/ P. Sima 2017-2020
18.5187°

SK Palarikovo 48.0392°/ P. Sima 2017-2020
18.0698°

SK Sturovo 47.7978°/ P. Sima 2017-2020
18.7158°

SK Trenéin 48.8923°/ J. Lukas 2017-2020
18.0393°

SK Vieska nad Zitavou Mlynany 48.3217°/ P. Sima 10.10.2020
18.3700°

In the Czech Republic, sites with flowering ivy were found and searched for the occurrence
of C. hederae. All localities were situated in the south of the country, usually very close to
the border with Austria and Slovakia. In 2017, we investigated localities in Kostice, Lanzhot
and Breclav and, in 2018-2019, in Nové Hrady randomly, but the species was not
discovered. In 2020, the species was recorded in Kostice and Breclav and many other

8 Bogusch P et al

localities in the Region of Moravia, as well as in two localities in the south of Bohemia.
Altogether, we studied ivy flower visitors in 44 localities in the Czech Republic (16 in
Bohemia and 28 in Moravia). In Tables 1, 2, all observed sites are listed with the
coordinates, collector names and numbers of recorded specimens at each locality.

We observed the insects flying around and sitting on flowers of ivy during the warmest part
of the day (between 11 a.m. and 4 p.m.) from the end of August until mid-October.
Observations were only carried out at temperatures higher than 18°C in warm weather,
with sunny or only partially cloudy skies, with no rain and only slight wind. Each locality
was Studied for 45 minutes or a shorter time if the bee were discovered earlier. Specimens
of C. hederae were determined in the field and several individuals (usually one pair) from
each locality were collected and placed into 75% alcohol for the collection and further
revision. The identity of all collected specimens was checked in the laboratory by P.
Bogusch, J. LukaS, A. Piidal, M. Slachta and J. Straka. The collected individuals from
Slovakia are deposited in the collection of P. Bogusch, J. Lukas, A. Pridal and J. Straka
and individuals from the Czech Republic in the collections of P. Bogusch, A. Pridal and M.
Slachta. Maps were created using QGIS 3.6 software, localities and bees on ivy, were
photographed using a mobile phone camera.

Czech
republic

Dae
Slovakia

°
au “s fos
@_Gratisiava BB

0 20 40 60 80100 km

erate

Bratislava

Figure 1. EES]

Map of the Czech Republic and Slovakia. Localities with the occurrence of Colletes hederae
marked by a full circle and an empty circle were used for indication of a locality without record
of the species. The nearest sites in Austria, Germany and Hungary are marked by blue circles
and the possible routes of spreading towards Slovakia and the Czech Republic are shown by
arrows. The species occurrence in the largest towns Brno (Czech Republic) and Bratislava
(Slovakia) is shown in the maps under the top map.

The spread of Colletes hederae Schmidt & Westrich, 1993 continues — f ... 9

Results

We discovered adults of C. hederae in 19 localities in the Czech Republic (two in Bohemia
and 17 in Moravia) and in 24 localities in Slovakia (Fig. 1, Table 1). The species was first
discovered in Slovakia in 2017 in two localities: (1) Devinska Nova Ves, Sandberg and (2)
Bratislava, Raca, Potocna Street. In the first locality, more than ten males and females
flying around and on flowers of ivy were recorded, as well as males in the nearby locality of
Sandberg Natural Reserve (J. Straka and P. Bogusch, observed and collected). In the next
years, the species was discovered in an additional 22 localities, which were situated all
around the Slovak capital Bratislava and the furthest locality from the first record was
Pezinok (21 km north). In total, two records of C. hederae were documented also from
Hungary and Austria and both are really close to the localities situated inside or around
Bratislava. Interestingly, no specimens of C. hederae were observed towards the east and
north directions in the localities around Trencin, Nove Zamky, Komarno and Banska
Stiavnica (Fig. 1, Table 2).

Figure 2. EES
Locality of large population of Colletes hederae in Mikulov Castle (Czech Republic). Details of
a female on flowers of ivy (Hedera helix). Photographed by P. Bogusch.

In the Czech Republic, the species was first discovered in 2020 in 17 localities in the south
of Moravia and in two localities in the south of Bohemia. The first record was from Znojmo,
where the species was observed on flowering ivy in the garden of the administration centre
of Podyji National Park. Here, a strong population was discovered and many females were
collecting pollen. Similarly, large populations were recorded in two additional sites in the
same town and in Mikulov around a distance of 40 km from Znojmo, where the species

10 Bogusch P et al

was recorded in all five checked sites, forming very large populations (Fig. 2). In all other
sites, the species was found only in smaller numbers of individuals and probably is new
there, in contrast to Mikulov and Znojmo, where the existence of large populations
suggests that the bee has likely occurred there for a longer time. We searched for this
species at several sites in 2017, 2018 and 2019, but C. hederae was not found. It was
surprising to find C. hederae in four sites in Brno about 40 km north of Mikulov, but only
several individuals were recorded and it is probable that the species has only occurred at
these localities for a short amount of time. Recording this species in Brno required
patience, as catching two individuals involved a 45-minute wait. These localities in Brno
are the northernmost sites of occurrence of C. hederae in the Czech Republic.

In Bohemia, C. hederae was recorded in two localities in the southernmost part of the
country, in relatively small populations. These localities are situated in the small town,
Nové Hrady and the village, Byfiov. The species was not recorded in the city Ceské
Budéjovice and nearby areas, although seven sites were checked there for its occurrence.

Discussion

The discovery of C. hederae in the Czech Republic and Slovakia is the latest proof of the
spread of this species in northern and eastern directions. Since the species was not
recorded in the sites of occurrence in Slovakia in 2015 and the Czech Republic in 2017-
2018, we can suppose that C. hederae is a very new representative of the fauna of both
countries. Czech and Slovak populations most likely originate from Austria, where C.
hederae was first recorded in Vienna in 2006 (Teppner et al. 2009, Gusenleitner et al.
2012). It is quite surprising that the species was only discovered in the south of Slovakia
(Bratislava is only about 50 km from Vienna) after such a long time — 11 years later and in
Mikulov (80 km from Vienna) 14 years later. Perhaps, the weather conditions for spreading
(Frommer 2010) were more suitable in the last few seasons, which were exceptionally
warm in both winter and summer in Central Europe (Zahradnicek et al. 2021). Spreading to
Znojmo could be more difficult, whilst the species was recorded nearby in Austria, around
Linz, but much later than in Vienna (Ebmer et al. 2018). While dispersal to Mikulov and
Bratislava would be through warm lowland regions, the expansion to Znojmo had to
partially pass through hilly and afforested areas. Similarly, Bohemian populations likely also
came from these locations.

Although C. hederae occurs in other neighbouring countries, it is evident that Czech and
Slovak populations originated from Austria. In Germany, the species was first discovered in
1991 (Schmidt and Westrich 1993), but following this, it was spreading especially in the
south-western parts of the country and migration was more towards the north than the east
(Jacobi et al. 2015). In recent studies, the nearest locality to the Czech Republic is
Freising, where the species was recorded in 2015 (Fleischmann 2019). It is situated
around 150 km from the German/Czech border and 210 km from the nearest localities of
C. hederae in the Czech Republic. Newer German records (2017-2019) are from Berlin
and Halle in central to northern Germany (Saure et al. 2019, Saure 2020), but these
localities are far from the Czech localities of C. hederae. Additionally, in Hungary, the

The spread of Colletes hederae Schmidt & Westrich, 1993 continues — f ... 11

species was first recorded in 2016 near Balaton Lake (Voigt and Szalai-Dobosne 2019),
which is even further from Slovak localities than the localities in Austria (140 km from
Bratislava).

The sudden occurrence of C. hederae in the Czech Republic and Slovakia is somewhat
similar to the situation in Graz, Austria (Teppner et al. 2009). With respect to the monitoring
of many sites in the south of both countries with negative results, the species spreading
seems to be not so “stormy” as Gusenleitner et al. (2012) recorded in Austria (“... seitdem
in sturmischer Ausbreitung”). Czech and Slovak populations are usually small, which can
relate to their relatively recent origin (most of the localities have been inhabited by ivy bee
probably for one or two years). Strong populations in Mikulov and Znojmo can be explained
by an earlier colonisation of both towns. Both towns probably provide suitable habitats for
this bee — they are situated in the warmest parts of the country, both on south-orientated
hillsides, with many possible vertical or semi-vertical clayish or loess walls for nesting and
with medieval entrenchment and historical buildings, richly overgrown with Hedera helix.
Bratislava has quite similar characteristics and the populations of C. hederae are large
there, too.

Interestingly, the species occurs in Greece, where it is numerous on Lesbos Island, as well
as occurring in the mainland (Vereecken et al. 2006, Vereecken et al. 2009) and Crimea in
Russia (Proshchalykin et al. 2017). However, no records are known from Romania,
although the monitoring of possible localities has been performed by specialists (B.
Tomozei, pers. commun.) and a similar situation is present in Bulgaria (T. Ljubomirov, pers.
commun.). The terrestrial routes of the spreading of the ivy-bee towards Crimea and
Greece remain unclear and the spreading is certainly faster in some directions than in
others. However, fragmented distribution ranges are not uncommon in the Mediterranean
Basin and SE Europe (Kuhlmann, pers. commun.), as is the case for other species.
Therefore, it might be that isolated populations exist in a wider area leaving large regions
uninhabited. Kuhlmann et al. (2007) hypothesise that the ivy bee is under an unfinished
dispersal process using arguments on distribution of the host plant, the recent colonisation
of southern England and with postglacial dispersal limits of its cuckoo bee. In Fig. 3, the
current distribution of the ivy-bee is depicted with a year of the first record for each country.

Although several authors declared that this species is observable from September to
December (Bischoff et al. 2005, Roberts and Vereecken 2010, but in maritime climates in
England), in more continental Central Europe, the species reacts to the colder weather in
late autumn and winter and occurs at the latest till the end of October and only in the case
of exceptionally warm and sunny weather. The flight activity on ivy was observed in
Bratislava (streets Zizkova and Kralovské Udolie) on 23.9.2019 even after 6 p.m. Most of
our observations are consistent with the species phenology, described by Bischoff et al.
(2005) despite there being potential for the species activity until the end of October
(Kuhlmann et al. 2007). The ivy-bee was recorded only on flowers of H. helix, but was
likely due to the fact that it was not searched for on flowers of other plants. Males were
also observed on flowers of other undetermined plants in Sandberg Nature Reserve and
these probably do not specialise on feeding only on ivy nectar. Although Bischoff et al.
(2005) reported that only pollen of H. helix was recorded in pollen loads of specimens

12 Bogusch P et al

observed in the UK, Muller and Kuhlmann (2008) and Westrich (2008) described C.
hederae to be polylectic with a strong preference for H. helix (or mesolectic, according to
Dotter! and Vereecken 2010). Identification of pollen loads from multiple females could
Clarify if the species also uses other plant species (e.g. Asteraceae, Ericaceae and
Orobanchaceae) as a source of pollen (Muller and Kuhlmann 2008, Westrich 2011,
Teppner and Brosch 2015), especially those flowering before the season of the ivy
(Westrich 2008).

} - 4 : - =f
‘ 0 250 500 750 1000 km [i
eto

Figure 3. EES

Distribution range map of Colletes hederae (green background) with the year of the first
record/specimen (in the case of publishing) and references for each country (Feitz 2001,
Gogala 1991, Gogala 1994, Lefeber 1998, Petit 1996).

Further monitoring in the Czech Republic and Slovakia is desirable to gain a better
understanding of the strategy in the spreading of this autumnal bee species, especially in
the context of the possible dispersal towards the north and the east. While this species
reached Slovakia in 2017 and the Czech Republic in 2020, it will be interesting to see if,
when and in which direction this species will move to Poland. The Moravian Gate
(Moravska brana) is considered as a migrating corridor to the north, not only for insect
species (Sierka et al. 2008). However, Banaszak et al. (2017) analysed bee populations in
“Gora Gipsowa” and indicated that the Moravian Gate does not play any part in the
migration of southern bee species to Poland at present. Therefore, monitoring of Colletes
hederae spreading through Moravia can help to explain the role of the Moravian Gate in
spreading of insects to Poland in Central Europe.

Conclusions

The spread of C. hederae evidently continues as confirmed by the new records from
Slovakia (2017) and Czechia (2020). These and recent records from Austria and Hungary
correspond with the north spread direction. It is not clear why, until recently, the ivy bee

The spread of Colletes hederae Schmidt & Westrich, 1993 continues — f ... 13

spread predominantly northwesterly. We hypothesise that spreading to the north could be
supported by the several last warm seasons (namely autumns) with a higher temperature
than their usual average. Monitoring of the continuation of the spread of the ivy bee is
important, not only to recognise its ecological limits, but also to verify the zoogeographic
importance of the Moravian Gate as a migration route.

Acknowledgements

We would like to give thanks to: Jiri MatuSka (Mikulov, CZ), Lenka Reiterova (Znojmo, CZ),
Nana Kralova (Praha, CZ) and Matej Zeit (Brno, CZ) for their help with selection of
localities, Michael Wiezik (Bratislava, SK) for a record from Bratislava and Zdenek
LaStuvka (Brno, CZ) and Stuart Roberts (Reading, England) for providing us with
consultations. Lucy Boulton (Lincoln, England) corrected the English. This study was partly
supported by the Technology Agency of the Czech Republic (TA CR), project No.
TH03030134.

Author contributions

Field surveys by all authors; conception and drafting of manuscript by P. Bogusch and A.
Pridal and draft revised by all authors; figures by P. Bogusch.

Conflicts of interest

Authors declare no conflicts of interest.

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