ACTA BIOLOGICA SLOVENICA 
LJUBLJANA 2013 Vol. 56, [t. 1: 3–9 
ACTA BIOLOGICA SLOVENICA 
LJUBLJANA 2013 Vol. 56, [t. 1: 3–9 
Achenes of common ragweed (Ambrosia artemisiifolia) in packages 

of sunflowerachenes 
foroutdoorbirds 


Plodovi pelinolistne žvrklje (Ambrosia artemisiifolia) v paketih soncnicnih 
plodov za prostoživece ptice 


Simona Strgulc Krajšeka*, Marko Novakb 

aUniversity of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 
SI-1000 Ljubljana, Slovenia 
bGimnazija Bežigrad, Periceva 4, SI-1000 Ljubljana, Slovenia 
*correspondence: simona.strgulc@bf.uni-lj.si 


Abstract:Common ragweed (Ambrosia artemisiifolia) is a highly invasive annual 
plant, introduced to Europe from North America. One of the important spreading 
vectors of Ambrosia is trading with contaminated sunflower achenes. We analysed 
the content of ragweed achenes in the packages of sunflower achenes for outdoor 
birds, which are available in Slovenian shops and markets. The ragweed achenes were 
found in 29% of the 28 analysed packages. In three packages, the mass percentage of 
Ambrosia achenes per kg of animal feed exceeded the maximum content (50 mg/kg) 
allowed by EU law. The analysis showed that it is not possible to infer the presence 
or absence of Ambrosia achenes in a sample from the amount of impurities in the 
package of sunflower achenes for bird feed. 


Keywords:Ambrosia artemisiifolia, Helianthus annuus,invasivespecies,ragweed, 
Slovenia, sunflower fruits 

Izvlecek: 
Pelinolistna žvrklja (Ambrosia artemisiifolia) je invazivna tujerodna 
enoletnica, 
ki 
je 
bila 
v 
Evropo 
prinesena 
iz 
Severne 
Amerike. 
Pomemben 
vektor 
širjenja vrste predstavlja transport in trgovanje s plodovi soncnic, ki vsebujejo prime-
šane plodove žvrklje. Vraziskavi smo preverjali prisotnost plodov žvrklje v paketih 
soncnicnih plodov za hranjenje prostoživecih ptic. Plodovi žvrklje so bili prisotni v 
29 
% od 28 paketov hrane za ptice, ki smo jih kupili v slovenskih trgovinah. V 
treh 
paketih je kolicina 
plodov presegala 
najvecjo doloceno kolicino plodov žvrklje, kot 
jo doloca evropska zakonodaja (najvec 50 mg/kg). Ugotovili smo tudi, da kolicina 
necistoc v paketu ni povezana s prisotnostjo plodov žvrklje. 

Kljucnebeside:Ambrosia artemisiifolia, Helianthus annuus,invazivnatujerodna 
vrsta, pelinolistna žvrklja, Slovenija, soncnicni plodovi 



Acta Biologica Slovenica, 56 (1), 2013 


Introduction 


Common ragweed (Ambrosia artemisiifolia) is 
an annual plant from the family Asteraceae.Itwas 
introduced to Europe from North America in the 
19th century (Csontos et al. 2010, Hegi 1979). In 
Europe it is considered an invasive alien species. 
Itpopulatesfields(corn,sunflower,pumpkin…), 
riverbanks,anddisturbedplacessuchasrailways 
and road edges (Hegi 1979). It is detrimental to 
human health as it produces highly allergenic pollen, 
which causes late summer hay fever (Kofol 
Seliger 2001, Taramarcaz 2005). 

The first records of the presence of Ambrosia 
artemisiifolia inSloveniaarefromLeskovecnear 
Krškoin1950(Wraber1983).Innextyearssome 
newlocalitieswerediscovered,andWraber(1983) 
marked this species as casual in Slovene flora, dis-
persedwithhumanactivities.Thefirstdataabout 
naturalisation of the species are from Prekmurje 
(Wraber 1983). In the last years the species has 
becomepresentinalmostalllowlandsinSlovenia, 
anditisnowknownasoneofmostinvasivealien 
plant species in Slovene flora (Jogan and Vreš 
1998, Jogan 2001, Jogan et al. 2009). 

Ambrosia artemisiifolia is an annual plant, 
0.2–2.5 m high. One or more male 
flowers are 
grouped 
in 
numerous 
much 
reduced 
capitula, 
which include one or more male flowers. Male 
capitula 
are 
grouped 
in 
racemes 
at 
the 
end 
of 
branches, while female flowers are located at the 
bases of upper leaves. Ambrosia artemisiifolia is 
ashort-dayplant,anditsfloweringtimebeginsin 
late summer (Allard 1943). Its fruits are achenes, 
each containing one seed. That is the reason for 
the 
simplified 
naming 
of 
ragweed 
achenes 
as 
seeds in non-botanical general use (newspapers, 
media …). Achenes usually drop off the mother 
plant,andtheybecomepartofsoilseedbank,but 
theymayalsobedispersedbywaterorbyhuman 
activities. 
Seeds 
have 
primary 
and 
secondary 
dormancy 
(Baskin 
and 
Baskin 
1980), 
and 
can 
remain 
viable 
for 
40 
years 
(Darlington 
1922, 
Telewski and Zeevaart 2002). 


One 
of 
the 
important 
spreading 
vectors 
of 
Ambrosia istradingwithcontaminatedsunflower 
seeds (more precisely: fruits or achenes) (Jehlik 
and Hejny 1974, Wraber 1983, Essl et al. 2009). 
Researchers in Austria have noticed that Ambrosia 
became frequent in habitats associated with bird 

feeding during the period 1950–1979 (Essl et al. 
2009). 
In 
the 
international 
European 
research 
performedinyears2005to2009,whichinvolved 
institutes from Switzerland, Germany, Denmark 
and Slovenia, Ambrosia achenes were found in a 

large proportion of the analysed sources of bird 

feed (Frick et al. 2011). 

The spread of Ambrosia in Slovenia is controlledbytwolegallyadoptedregulations.
Thefirstis 
CommissionRegulation(EU)No574/2011of16 
June 2011, concerned with undesirable contents 
of animal feed, including Ambrosia seeds(Anon. 
2011). The limit of intervention is 50 mg of Ambrosia 
seeds per kg of animal feed (Anon. 2011). 
The second is the Slovene regulation “Odredba 

o ukrepih za zatiranje škodljivih rastlin iz rodu 
Ambrosia” 
(Decree 
on 
measures 
to 
suppress 
harmful plants of genus Ambrosia), that obliges 
every citizen to remove all Ambrosia plants from 
hisproperty,andhehastopreventtheplantsfrom 
developing flowers and fruits (Anon. 2010). 


The aim of our research was to check if the 
packages 
of 
sunflower 
seeds 
for 
outdoor 
birds 
available in Slovene shops and markets contain 
ragweed 
achenes, 
to 
assess 
the 
extent 
of 
this 
contamination 
and 
to 
compare 
it 
with 
legally 
adopted regulations. 

Materials 
and 
methods 


In autumn of 2011 we collected 35 samples 
ofpackagesofsunflowerseedsforbirdfeedfrom 
variousshopsandmarketsinSloveniaforanalyses 
of 
ragweed 
contamination. 
The 
samples 
were 
planned to cover: (1) different parts of Slovenia, 

(2) different shops and suppliers, and (3) differ-
entpackagesizes.Everypackagewasnumbered, 
and the bills from the shops were stored together 
with the package to keep the information about 
the date and locality of the purchase. 
The following data have been collected from 
packagelabels:packageID,commercialname,size 
(weight), serial number or LOTnumber, country 
of sunflower fruit production, date of packaging, 
type 
of 
sunflower 
nuts 
(black, 
white, 
striped, 
mixed), and data about the purchase: location of 
shop, shop name, and date. 


Thefirststepinseparatingtheragweedachenes 
from sunflower achenes was hand-sieving. For 


Strgulc Krajšek and Novak: Ambrosia artemisiifolia in bird feed 

this 
purpose, 
a 
special 
sieve 
with 
1.5–2.3 
mm 
wire mesh size was made. Prior to examination 
ofthesamples,thesievewastestedwithartificial 
(prepared) 
mixture 
of 
sunflower 
and 
ragweed 
achenes. 
Since 
no 
ragweed 
achenes 
stayed 
on 
thesieve,andonlyafewsunfloweracheneswere 
smaller 
than 
the 
mesh 
size, 
we 
considered 
the 
hand-made sieve suitable enough for fractioning 
the samples. 


Secondly, the small fraction that presumably 
contained the Ambrosia acheneswasweightedand 
storedinaplasticbag.Thefractionwithsunflower 
achenes was weighted as well. 


Asmall fraction was further analysed using 
a stereomicroscope (20 × magnification) to sort 
out ragweed achenes. Achenes were weighted, 
counted and stored in a small plastic bag. 


There 
are 
two 
other 
species 
from 
genus 
Ambrosia present in Slovenia: A. psilostachya 
and A. trifida, but A. artemisiifolia is the most 
common one (Buttenschřn et al. 2008–09, Jogan 
2001). There is a minor possibility that some of 
theragweedfruitswefoundinbirdfeedbelonged 
to other Ambrosia species, since no detailed species 
determinationwas made based on Ambrosia 
achenesproperties.Accordingtothefrequencyof 
all Ambrosia species in Europe and Slovenia, we 
assumedthatthemajorityofachenesbelongedto 
Ambrosia artemisiifolia. 

Results 


35 packages of sunflower seeds for bird food 
were collected in different Slovene shops. Seven 
packageswereexcludedfromtheanalysisbecause 
it was not possible to isolate ragweed achenes by 
using the described methods. 

Altogether, 2 packages of 5 kg, 24 packages 
of 1 kg, one package of 0.6 kg, and one package 
of 0.5 kg of bird feed were analysed (Table 1). 

We included 13 different producers or importing 
companies of bird feed, but it is possible that 
theyhadthesamesourceofrawmaterial.Thedata 
about the origin of the sunflowers were absent 
from the majority 
of the packages labels. They 
were written only on 8 packages (23%). 

TheresultsoftheanalysisareshowninTable 

2. Ragweed achenes were found in 8 packages 
of bird feed (29%). In three packages, the mass 
percentage of Ambrosia seeds per kg of animal 
feed 
exceeded 
the 
maximum 
content 
(50 
mg) 
allowed by EU law (Anon. 2011). Producers of 
these 
three 
packages 
were 
Agrolit, 
Semenarna 
Ljubljana and AnimaPet. 

We have included more than one sample of 
bird feed from the same producer (Erdtmanns, 
Agrolit, Tukano, and Semenarna Ljubljana), and 
the same series of raw material in our analysis 
(Table 3). It is apparent, that there are big differ-
encesincontentsofragweedachenesinpackages 
withinthesamplesofthesameproducer,andeven 
withinthesameseriesoftherawmaterial(0or35 
ragweed achenes in 1 kg of bird feed in the case 
of Semenarna Ljubljana, 105-PC, Table 3). 

The 
analysis 
of 
correlation 
between 
the 
numberofragweedachenesandthecontentofthe 
small fraction (impurities) in the sample showed 
that there is no clear connection between these 
parameters. Therefore we cannot infer the presence 
or absence of Ambrosia seeds in a sample 
justfromtheamountofimpuritiesinthepackage 
of sunflower achenes for bird feed. 

Discussion 

Ragweed achenes were found in one third of 
the 28 analysed packages of bird feed. In three 
packages, the mass percentage of Ambrosia seeds 
per 
kg 
of 
animal 
feed 
exceeded 
the 
maximum 
content(50mg)allowedbyEUlaw(Anon.2011). 
Thus, these packages should not be sold. From a 
biological point of view, all packages containing 
one or more seeds of Ambrosia are problematic. 
Only one successfully germinated seed that develops 
into a flowering and afterwards fruiting 
plant 
is 
enough 
to 
establish 
a 
new 
population 
of Ambrosia. Although a smaller number of the 
seedsreducesthepossibilityofsuchevent,itstill 
makes it possible. 

The National Veterinary Institute conducted 
a similar investigation in 2007/08 and 2008/09, 
analysing10samplesofbirdfeedeachyear(Frick 
et al. 2011). Ambrosia acheneswerefoundin7and 
5 samples, respectively, with the highest amount 
of 292 Ambrosia achenes per kg of bird feed. In 
our samples from 2011, the contamination with 
Ambrosia acheneswaslower(33%ofcontaminated 
samples with maximum 198 Ambrosia achenes 


Acta Biologica Slovenica, 56 (1), 2013 


Table 1: 
Information about the packages of sunflower fruits for bird feed used in the analysis. Packages no.: 2, 
6, 7, 10, 11, 19 and 22 (grey shading) were excluded from the analysis (explanation in the text). × – no 
data, *unpacked sunflower achenes with no commercial name bought on a food market. 


Tabela 1:Informacije o paketih soncnicnih plodov za hranjenje zunanjih ptic, ki smo jih zbrali za analizo. Pakete 
2, 6, 7, 10, 11, 19 in 22 (siva podlaga) smo iz analize izkljucili (razlaga v besedilu). × – ni podatkov, 
*nepakirani soncnicni plodovi kupljeni na tržnici. 

Sample Commercial name Producer/Importing 
Lot/Series 
Package Countryoforigin 
number 
company size (kg) of 
sunflowers 


1 
Sonnenblumen Kerne 
Erdtmanns 
210910 
1 
x 

2 
Bonami 
Semenarna Ljubljana 
105-PC 
1 
x 

3 
Bela soncnicna semena 
Versele_Laga 
B-9800 
0.6 
Belgium 


4 
Soncnice pisane 
Roko 480-43486 
1 
Hungary 

5 
Hobby Vit 
Tukano 21300040 
1 
Bulgaria 

6 
Menu Complete 
Friskies EAN 
0.4 
x 

7 
Lojna pogaca 
Vogel pick 
21305065 
0.2 
x 

8 
Soncnicna semena 
Tukano 21300042 
1 
Bulgaria 

9 
Bonami, Soncnice pisane Semenarna Ljubljana 
460-PC 
5 
x 
za 
pticjo hrano 


10 
Bonami, Hrana za zunanje Semenarna Ljubljana 
P1330 
5 
x 
ptice 

11 
Bonami, Mešanica semen 
Semenarna Ljubljana 
70507015 
1 
x 

12 
Bonami, Semena soncnic 
Semenarna Ljubljana 
460-PC 
1 
x 

13 
Bonami, Soncnice Mešane 
Semenarna Ljubljana 
P1279 
1 
x 

14 
Hobby Vit 
Tukano M1/17:21:29 1 
x 
/10/10/11 


15 
Soncnicna semena 
Roko 480-43486 
1 
x 

16 
Bonami 
Semenarna Ljubljana 
105-PC 
1 
x 

17 
Soncnice Mešane 
Semenarna Ljubljana 
P1278 
5 
x 

18 
Soncnice pisane 
Zoo hoby Škofja Loka 0013 
1 
x 

19 
Hobby Vit 
Tukano 11246 
1 
x 

20 
Sonnenblumen Kerne 
Tierell 772013 
1 
x 

21 
Bonami, Mešanica semen 
Semenarna Ljubljana 
P1331 
1 
x 

22 
Bonami, Semena soncnic 
Semenarna Ljubljana 
460-PC 
1 
x 

23 
Soncnicna semena 
Agrolit 19. 9. 2011 
1 
x 

24 
Bonami, Semena soncnic 
Semenarna Ljubljana 
105-PC 
1 
x 

25 
Hobby Vit 
Tukano 21300042 
1 
Bulgaria 

26 
Soncnicna semena 
Roko 11/210 
1 
Hungary 

27 
Soncnicna semena 
Agrolit 4. 12. 2010 
1 
EU 

28 
Soncnicna semena 
Agrolit 19. 9. 2011 
1 


29 
Sonnenblumen Kerne 
Erdtmanns 
210910 
1 


30 
Sonnenblumen Kerne 
Erdtmanns 
210910 
1 


31 
Futter Boy Erdtmanns 
210829 
0.5 


32 
Hesa Saaten Tierell CHA70 
1 
x 

33 
Soncnicna semena 
Hobby program 
21300042 
1 


34 
Soncnicna semena 1kg 
AnimaPet 
598.10 
1 
EU 

35 
x* food market 
x 1 



Strgulc Krajšek and Novak: Ambrosia artemisiifolia in bird feed 

Table 2: 
Presence of ragweed achenes in the analysed packages of the bird feed. 
Tabela 2:Prisotnost plodov žvrklje v pregledanih paketih pticje hrane. 


Sample 
number 
Content 
of 
ragweed 
Number 
of 
ragweed 
Mass 
% 
of 
the 
small 
achenes (mg/kg) achenes fraction 
(including 
ragweed) 

24 
198 35 
1.9 
23 
61 11 
0.5 
34 
51 9 
0.7 


28 
45 8 
0.5 
29 
34 6 
0.3 
14 
6 1 
0.3 
22 
6 1 
0.3 
17 
1 1 
0.1 
1 
0 0 
0.3 
3 
0 0 
0.4 
4 
0 0 
0.2 
5 
0 0 
6.8 
8 
0 0 
0.4 
9 
0 0 
0.1 
12 
0 0 
0.3 
13 
0 0 
0.5 
15 
0 0 
0.2 
16 
0 0 
0.4 
18 
0 0 
0.2 
20 
0 0 
0.4 
25 
0 0 
0.4 
26 
0 0 
0.2 
27 
0 0 
2.2 
30 
0 0 
0.3 
31 
0 0 
0.7 
32 
0 0 
0.4 
33 
0 0 
0.7 
35 
0 0 
0.4 


perkgofbirdfeed),whichmayindicateagradual 
decrease of the contamination level in bird feed 
available on Slovene market. 


InSlovenia,everycitizenisobligedtoremove 
all Ambrosia plants from his property and he has 
to 
prevent 
the 
plants 
from 
developing 
flowers 
(because of the allergenic pollen) and fruits (to 
limit 
their 
dispersal) 
(Anon. 
2010). 
Therefore 
it 
is 
very 
important 
to 
inform 
people 
that 
it 
is 
highly possible to introduce Ambrosia into gardens 
with 
contaminated 
bird 
feed. 
In 
Slovenia 
this 
is 
already 
in 
progress. 
Informations 
about 
Ambrosia and the related problems were already 
published in public journals (Jogan 2011, Bacic 

2012,StrgulcKrajšek2013),projectpublications 
(for example: Buttenschřn et al. 2008–09), and 
ondifferentwebsites(forexample:ProjectThuja: 
http://www.tujerodne-vrste.info, DOPPS: http:// 
www.ptice.si). 

Povzetek 


Pelinolistnažvrklja(Ambrosia artemisiifolia) 
je ena najbolj razširjenih invazivnih tujerodnih 
rastlinskih vrst na obmocju Slovenije (Jogan et 
al. 
2001). 
Gre 
za 
severnoameriško 
vrsto, 
ki 
je 
bila v 19. stoletju nehote prinesena v Evropo in 


Acta Biologica Slovenica, 56 (1), 2013 


Table 3: 
Differences in number of ragweed achenes among the packages of bird feed of the same producer, or the 
same series of the raw material. 


Tabela 3:Razlike v prisotnosti plodov žvrklje med paketi istega proizvajalca in iste serije paketov soncnicnih 
plodov. 

Producer, Series Sample Package Mass 
of 
small 
fraction 
Number 
of 
ragweed 
number 
size (kg) (including ragweed) (g) achenes 
1 
1 
2.9 
0 
Erdtmanns, 210910 
29 
1 
3.2 
6 
30 
1 
3.0 
0 
Agrolit, 23 
1 
5.5 
11 
19. 9. 2011 
28 
1 
5.0 
8 
33 
1 
6.8 
0 
Tukano, 21300042 
25 
1 
3.6 
0 
8 
1 
4.4 
0 
Semenarna Ljubljana, 24 
1 
18.9 
35 
105-PC 
16 
1 
3.9 
0 
Semenarna Ljubljana, 
460-PC 
9 
22 
12 
5 
1 
1 
4.8 
3.1 
3.5 
0 
1 
0 


seširipredvsemobželeznicah,cestah,ruderalnih 
mestih in poljih (Jogan 2009). Problematicna je 
zaradi 
alergenega 
peloda, 
ki 
povzroca 
poznopoletni 
seneni 
nahod. 
Eden 
od 
pomembnejših 
vektorjev 
razširjanja 
je 
prenos 
plodov 
žvrklje 
skupaj 
s 
soncnicnimi 
plodovi, 
ki 
jih 
prodajajo 
za hranjenje prostoživecih ptic (Essl et al. 2009, 
Frick et al. 2011). 

V 
okviru 
raziskave 
smo 
pregledali 
pakete 
soncnicnih plodov za hranjenje ptic, ki so naprodaj 
v trgovinah v Sloveniji. Naš namen je bil 
ugotoviti, 
v 
kolikšni 
meri 
se 
v 
njih 
pojavljajo 
plodovi(oreški)pelinolistnežvrklje.Paketehrane 
zapticesmonakupilijesenileta2011.Zbralismo 
35 
paketov, 
od 
katerih 
jih 
7 
nismo 
pregledali, 
ker se z izbranimi metodami iz njih ni dalo lociti 
plodov žvrklje. Za izolacijo plodov žvrklje smo 
uporabili 
metodi 
sejanja 
skozi 
sito 
in 
rocnega 
prebiranjavzorca.Izmed28pregledanihpaketov 
pticje hrane, smo plodove žvrklje našli v 8 paketih, 
kar predstavlja29 % pregledanih vzorcev. V 
treh paketih je kolicina plodov žvrklje presegala 
zakonsko 
predpisano 
zgornjo 
dovoljeno 
mejo 
masnegadeležaplodovpelinolistnežvrklje(Anon. 
2011),karustreza9plodovompelinolistnežvrklje 
na kilogram pticje krme. Ugotovili smo veliko 

raznolikost vsebnosti plodov žvrklje 
med paketi 

istega proizvajalca (uvoznika) in celo znotraj iste 

serijepakiranjasoncnicnihplodov,karjeverjetno 
povezano z nacinom pakiranja plodov. Kolicina 
necistoc, 
ki 
jih 
predstavlja 
drobna 
frakcija 
po 
sejanju vzorca skozi sito, v paketu ni povezana s 
kolicino plodov žvrklje. 

Naslovenskemtržišcusotorejvprodajipaketi 
soncnicnih plodov za hranjenje zunanjih ptic, ki 
vsebujejo plodove žvrklje, celo s kolicinami, ki 
presegajozakonskodolocenozgornjomejo.Nujno 
je obvešcanje potrošnikov o tem problemu, saj 
lahko zaradi priljubljenega zimskega hranjenja 
ptic 
posamezniki 
nehote 
razširjajo 
to 
alergeno 
rastlino in jo celo 
zanesejo na svoje vrtove, od 
koder pa jo morajood v skladu z odredbo iz leta 
2010 odstranjevati (Anon. 2010). 

Acknowledgements 


We would like to thank Metka Škornik from 
Gimnazija 
Bežigrad 
for 
technical 
support, 
and 
Tinka 
Bacic 
for 
critical 
reading 
of 
the 
manuscript. 



Strgulc Krajšek and Novak: Ambrosia artemisiifolia in bird feed 

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