Seasonal Phenology and Species Composi ion o he
Aphid Fauna in a No he n C op P oduc ion A ea
Sascha M. Ki chne
1,2
*, Lea Hil unen
2
, Thomas F. Do
¨ ing
3
, Elina Vi anen
2
, Jukka P. Palohuh a
4
,
Ja i P. T. Valkonen
1
1Depa men o Ag icul u al Sciences, Uni e si y o Helsinki, Helsinki, Finland, 2MTT Ag iFood Resea ch Finland, Oulu, Finland, 3Depa men o C op and Animal
Sciences, Humbold -Uni e si a
¨ , Be lin, Ge many, 4Finnish Seed Po a o Cen e, Ty na
¨ a
¨, Finland
Abs ac
Backg ound:
The species di e si y o aphids and seasonal iming o hei ligh ac i i y can ha e signi ican impac s on c op
p oduc ion, as aphid species di e in hei abili y o ansmi plan i uses and ligh iming a ec s i us epidemiology. The
aim o he s udy was o cha ac e ise he species composi ion and phenology o aphid auna in Finland in one o he
no he nmos in ensi e c op p oduc ion a eas o he wo ld (la i ude 64u).
Me hodology/P incipal Findings:
Fligh ac i i y was moni o ed in ou g owing seasons (2007–010) using yellow pan aps
(YPTs) placed in 4–8 seed po a o ields and a Ro hams ed suc ion ap. A o al o 58,528 winged aphids we e ob ained,
iden i ied o 83 axa based on mo phology, and 34 species we e addi ionally cha ac e ised by DNA ba coding. Seasonal
ligh ac i i y pa e ns analysed based on YPT ca ch ell in o h ee main phenology clus e s. Monoecious axa showed ea ly
o middle-season ligh ac i i y and belonged o species li ing on sh ubs/ ees o he baceous plan s, espec i ely.
He e oecious axa occu ed o e he en i e po a o g owing season (ca. 90 days). Abundance o aphids ollowed a clea 3-
yea cycle based on suc ion ap da a co e ing a decade. Rhopalosiphum padi occu ing a he end o he po a o g owing
season was he mos abundan species. The ligh ac i i y o Aphis abae, he main ec o o Po a o i us Y in he egion, and
Aphis gossypii peaked in he beginning o po a o g owing season.
Conclusions/Signi icance:
De ailed in o ma ion was ob ained on phenology o a la ge numbe aphid species, o which
many a e ag icul u ally impo an pes s ac ing as ec o s o plan i uses. Aphis gossypii is known as a pes in g eenhouses,
bu ou s udy shows ha i occu s also in he ield, e en a in he no h. The no el in o ma ion on aphid phenology and
ecology has wide implica ions o p ospec i e pes managemen , pa icula ly in ligh o clima e change.
Ci a ion: Ki chne SM, Hil unen L, Do
¨ ing TF, Vi anen E, Palohuh a JP, e al. (2013) Seasonal Phenology and Species Composi ion o he Aphid Fauna in a
No he n C op P oduc ion A ea. PLoS ONE 8(8): e71030. doi:10.1371/jou nal.pone.0071030
Edi o : Alex C. C. Wilson, Uni e si y o Miami, Uni ed S a es o Ame ica
Recei ed Decembe 27, 2012; Accep ed June 28, 2013; Published Augus 13, 2013
Copy igh : ß2013 Ki chne e al. This is an open-access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License, which pe mi s
un es ic ed use, dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal au ho and sou ce a e c edi ed.
Funding: This wo k was suppo ed by he Minis y o Ag icul u e and Fo es y, Finland (g an s 618/502/2008 and 2383/312/2009). The unde s had no ole in
s udy design, da a collec ion and analysis, decision o publish, o p epa a ion o he manusc ip .
Compe ing In e es s: The au ho s ha e he ollowing in e es s: The Finnish Seed Po a o Cen e and No he n Seed Po a o p o ided assis ance and suc ion ap
da a. The e a e no pa en s, p oduc s in de elopmen o ma ke ed p oduc s o decla e. This does no al e he au ho s’ adhe ence o all he PLOS ONE policies on
sha ing da a and ma e ials.
* E-mail: sascha.ki chne @helsinki. i
In oduc ion
The li e cycles o aphid species di e and exhibi a ious
pa e ns o polymo phism [1]. Aphids can be g ouped acco ding
o hei ela ionships wi h hos plan s o he e oecious (hos -
al e na ing) and monoecious (non hos -al e na ing) species [2],
which is e lec ed in he phenology o aphid popula ions, i.e., in
he speci ic empo al pa e ns o ligh ac i i ies wi hin a yea , o ,
as in ag icul u al con ex s, wi hin a g owing season. The seasonal
pa e n o ligh ac i i y o hos -al e na ing species can be seen as
an indica o o he op imal ime o hos ans e be ween p ima y
(mainly woody) and seconda y (he baceous) hos s. In non hos -
al e na ing species, seasonal ligh pa e ns a e likely o e lec he
ime window o sp eading clones be o e hos quali y s a s o
de e io a e [2].
Aphid phenology, howe e , is no only dependen on species-
speci ic ela ionships be ween he aphid and he hos plan , bu i is
also la gely in luenced by local en i onmen al ac o s such as
pho ope iod and mean win e empe a u es [3]. Du ing he
g owing season, clima ic ac o s in luencing aphid phenology a y
and a e challenging o p edic . Fu he complexi ies a e
in oduced, because he iming o ap ca ch is no only dependen
on inna e phenology bu also aphid abundance. High abundance
will lead o inc eased p obabili y o cap u e and ea lie ecogni ion
o he ligh . Aphid abundance is pa icula ly di icul o p edic ,
due o he dynamic esponses o aphid popula ions o p eda ion,
diseases o pa asi a ion [4]. Fo hese easons, egula i ies in he
ligh ac i i ies o aphids a e no o iously di icul o ex ac e en
om long e m da a se s.
Phenology can ha e a signi ican impac on he pes s a us o
aphid species. Fo example, phenology de e mines a which
g ow h s age he c op is likely o be in aded by aphids and which
c ops a e likely o be a ec ed mos se e ely [5]. Aphid phenology
has pa icula ly impo an implica ions o ansmission o aphid-
ec o ed plan i uses, because inocula ion o plan s wi h i uses a
an ea ly g ow h s age esul s in highe a es o in ec ion [6–9].
PLOS ONE | www.plosone.o g 1 Augus 2013 | Volume 8 | Issue 8 | e71030
The e o e, imp o ing he knowledge on aphid phenology is use ul
o planning plan p o ec ion s a egies, in pa icula wi h ega ds
o aphid- ansmi ed i uses.
A a b oad geog aphic scale, compa ing aphid species occu ing
in empe a e zones wi h hose ound in suba c ic egions e eals ha
he highe la i udes a e cha ac e ised by a lowe p opo ion o
anholocyclic clones and winged (ala e) aphids [10]. The ligh s o
aphids in he sp ing s a la e [11] consis en wi h he la e beginning
o plan g owing season. Hence he li e cycle o aphids is limi ed o a
sho ime window, which educes he ime, e.g., o coexis ence o
i uses and ec o s and educes in ec ion p essu e [9].
The Ty na¨ a¨-Liminka a ea o Finland (ca. 64uN) is cha ac-
e ised by a sho he mal g owing season om May o ea ly
Oc obe , wa m summe s and ela i ely cold win e s. The egion is
one o he i e Eu opean High G ade Seed Po a o P oduc ion
Zones (HG zones) ecognised by he Eu opean Union. In 2012, ca.
27300 onnes o seed po a oes we e p oduced on 1000 ha o ield
[12]. Sys ema ic s udies on aphid ligh phenology in Ty na¨ a¨-
Liminka a ea and o he no he n ag icul u al egions in he wo ld
a e ela i ely a e. The s udies ha e been ocused on selec ed
aphid species, such as ce eal aphids ansmi ing ba ley yellow
dwa i uses o he ela i ely ew species ansmi ing Po a o i us Y
(PVY) in Finland and Sweden [13–16]. The e o e, he aim o his
s udy was o p o ide mo e comp ehensi e and sys ema ic
in o ma ion on he phenology and species composi ion o he
aphid auna in he Ty na¨ a¨-Liminka a ea ep esen ing an
ag icul u ally impo an egion wi h an unusually no he n
loca ion. The da a ha e been u ilized in a no el modelling
app oach e ealing ha Aphis abae is he main ec o o Po a o i us
Yin he egion [9], bu he phenology and species composi ion o
he aphids a e epo ed he e. The low p obabili y o anholocycly
[17] in he egion p o ided unique oppo uni ies o s udy aphid
phenology in a less complexi y-laden en i onmen whe e ex ac-
ion o phenological pa e ns may be easie .
Ma e ials and Me hods
E hics S a emen
No speci ic pe mi s we e equi ed o he desc ibed ield s udy.
Addi ionally, we go o al app o als o insec sampling om all
p i a e land owne s. The collec ions did no in ol e endange ed o
p o ec ed species.
En i onmen al condi ions
The s udy was ca ied ou in he Ty na¨ a¨-Liminka a ea
(64u46N, 25u32E; ca 100 km
2
) in he coas al zone o he Gul o
Bo hnia, 2–10 m abo e sea le el (Fig. 1) in 2007–2010. The mean
he mal g owing season (T
base
=5uC) begins on May 1 and ends
on Oc obe 9 (a e age o yea s 1981–2010) [18]. A ypical iew on
he ag icul u al landscape, espec i e cumula i e e ec i e empe -
a u e, cumula i e p ecipi a ion and dayligh hou s a e shown in
Figu e 2. The landscape was s uc u ed by ag icul u al a eas
su ounded by young o middle-aged mixed o es (Be ula spp.,
Pinus spp. and Picea spp.).
Aphid moni o ing
In ou yea s (2007–2010), aphid ligh s we e moni o ed o e
he po a o g owing season, which s a s in mid-June and ends in
he beginning o Sep embe in he Ty na¨ a¨-Liminka a ea. Yellow
pan aps (YPT) (Syngen a Ag o GmbH, Main al, Ge many) we e
used o s udy local occu ence o aphids in 4 o 8 ields pe yea .
YPTs we e 27.0633.068.0 cm (wid h x leng h x heigh ) and illed
wi h ca. 1.5 l o ap wa e con aining 1 ml o 50% Tween20 as an
odou less de e gen . Single YPTs pe ield we e used in 2007,
whe eas in 2008–2010, h ee YPTs we e used in each ield. The
h ee YPTs we e a anged in a iangle (dis ance 1.5 m be ween
YPTs) [9] and he o al ca ch o aphids om hem was used o
analysis because o he low aphid abundance. The numbe o
aphids caugh in 2007 was mul iplied by a ac o o 2.79 o make
da a compa able o yea s 2008–2010. The ac o was de e mined
by a calib a ion expe imen in 2008 (see [9] o u he de ails).
Each ap was placed on a black box (60640616 cm) u ned
upside down and si ua ed a an edge o a po a o ield in he middle
o an a ea o 464 m main ained as a ba e allow by he bicide
ea men s o ensu e uni o mi y o he condi ions o apping o e
si es and pe iods o ime [19]. YPTs we e emp ied wice a week.
All YPTs we e eplaced by new ones in he middle o he po a o
g owing season, because bleaching o he yellow colou o aps
may occu g adually upon exposu e o sunligh [20] and in luence
he landing esponse o aphids [21],[22].
The ligh ac i i y o aphids was moni o ed using a 12.2 m high
Ro hams ed suc ion ap [23] cen ally loca ed in he esea ch
a ea. The suc ion ap was emp ied daily.
Species iden i ica ion
Aphid ca ches om bo h ypes o ap we e s o ed in 70% e hanol.
Aphids we e iden i ied using a mic oscope (50–100X magni ica-
ion) and a ious axonomic keys [24],[25],[26],[27],[28],[29],[30].
Indi iduals which could no be iden i ied o species we e g ouped a
genus le el. Aphis abae s.s. and Aphis abae subspecies we e no
sepa a ed [26] bu assigned o Aphis abae g oup. G ouping o species
acco ding o he li e cycle was done based on a hos plan ca alogue
o aphids [31].
DNA ba coding was done o complemen mo phological
iden i ica ion. To al DNA was ex ac ed om single aphid
indi iduals using DNeasy Blood & Tissue Ki (Qiagen, Hilden,
Ge many) acco ding o he manu ac u e ’s supplemen a y p o o-
col o insec s. Ba coding was done based on a 658-bp long egion
o he mi ochond ial gene o cy och ome coxidase I (COI)
ampli ied using p ime s LepF (59-ATTCAACCAATCATAAA-
GATATTGG-39) and LepR (59-TAAACTTCTGGATGTC-
CAAAAAATCA-39) [32]. PCR was done in a o al olume o
50 ml and con ained 5% ehalose, 10 mM T is-HCl (pH 8.8),
50 mM KCl, 0.1% T i on X-100, 3 mM MgCl
2
, 5 pmol o each
p ime , 1.4 uni s Dynazyme II (Finnzymes, Espoo, Finland),
50 mM dNTP, and 10–50 ng DNA. The PCR p og amme
consis ed o a 2 min p e-incuba ion a 94uC, ollowed by 40
cycles o 40 seconds a 94uC, 40 seconds a 49uC and 1 min a
72uC. Final ex ension was done o 5 min a 72uC.
PCR p oduc s we e de ec ed on 1.0% T is-ace a e-EDTA
aga ose gels by elec opho esis ollowed by s aining wi h e hidium
b omide. PCR p oduc s o he expec ed size we e sequenced in
bo h di ec ions wi h LepF and LepR p ime s by he Sequencing
Labo a o y o he Haa man Ins i u e, Uni e si y o Helsinki,
Finland. BioEdi so wa e was used o e alua ing he quali y o
sequence da a and also o he alignmen o sequences. Sequences
and addi ional in o ma ion on ouche ma e ial we e uploaded o
he Ba code o Li e Da a (BOLD) Sys ems da abase (h p://www.
boldsys ems.o g; p ojec code ‘AFNF’). Vouche s a e a ailable a
he Finnish Museum o Na u al His o y/Zoology Uni , Helsinki,
Finland, unde accession numbe s AFNF001-12 o AFNF0039-12.
Sequences ob ained in his s udy we e compa ed wi h sequences
ob ained om he BOLD Sys ems da abase. Fo sequence
alignmen , longe sequences we e cu o he s anda dised leng h
o 658 bp o he ba code egion o COI. Sequences which we e
sho e han 658 bp o had missing alues we e excluded om he
alignmen . Neighbou -joining analysis o sequences was done wi h
Mega4 so wa e, as desc ibed [33].
Phenology o Aphids unde No he n Clima e
PLOS ONE | www.plosone.o g 2 Augus 2013 | Volume 8 | Issue 8 | e71030
Analysis o da a
Cha ac e isa ion o seasonal ligh pa e ns was based on he ca ch
om YPTs. Aphid species ep esen ed by less han 10 indi iduals in
he o al ca ch o he yea we e omi ed. Da a p epa a ion was done
in h ee s eps o ensu e ha all aps con ibu ed equally o an
a e aged seasonal ligh pa e n o a species and ha aps wi h high
numbe s o aphids did no o e ly domina e phenology cha ac e -
is ics o aps wi h low o e all aphid numbe s [34],[35]. Fi s , o
each week (k) and species (e) o a pa icula ap [si e-by-yea
combina ion (i)], coun s o indi iduals o a species (c)we edi idedby
he o al coun o he species o he si e-by-yea combina ion (eqn1)
conce ned, esul ing in a s anda dised coun (
kei
).
kei~ckei=X
36
k~25
ckei ð1Þ
Second, esul ing seasonal ligh pa e ns we e a e aged o e all
aps (i) (si e-by-yea combina ions) pe species and deno ed as (n
ke
)
,
(eqn 2),
nke~
1
Ie

X
Ie
i~1
kei ð2Þ
whe e (I
e
) is he o al numbe o si e-by-yea combina ions o
which he e was a leas one indi idual in species (e). In o he
wo ds, he (n
ke
) a e age includes only hose si e-by-yea combina-
ions (i) o which species (e) was p esen . Thi d, he esul ing
a e ages (n
ke
) we e no malised o hei espec i e peaks o allow
compa isons be ween species.
yke~
nke
maxknke
ðÞ
 ð3Þ
No malised and a e aged ligh pa e ns (y
e
) we e hen analysed by
hie a chical clus e ing gene a ed wi h he R package ‘P clus ’ [36]
in R, e sion 2.15.1 [37]. The p ocedu e was pe o med wi h
mul iscale boo s ap wi h 10,000 epe i ions, a e age linkage o
clus e joining and a maximum-based dissimila i y ma ix.
Figu e 1. Map o he No dic coun ies. The egion unde s udy (Ty na
¨ a
¨-Liminka a ea; 64u46N, 25u32E; ca 100 km
2
) in Finland is shown in ed.
doi:10.1371/jou nal.pone.0071030.g001
Phenology o Aphids unde No he n Clima e
PLOS ONE | www.plosone.o g 3 Augus 2013 | Volume 8 | Issue 8 | e71030
App oxima ely Unbiased (AU) p obabili y alues we e compu ed
using boo s ap samples o a ious sizes o es how s ongly he
clus e was suppo ed (AU.95%). Fligh pa e ns o species ha
clus e ed oge he we e a e aged o e species (eqn 4) and
no malised o hei espec i e peak (eqn 5) o ob ain ypical
phenology pa e ns,
pkh~
1
Eh

X
Eh
e~1
ykð4Þ
whe e (h) is he clus e and (E) he numbe o species in ha clus e .
qkh~
pkh
maxknkh
ðÞ
 ð5Þ
Resul s
Aphid auna
A o al o 58,528 winged aphid indi iduals we e caugh in
2007–2010, including 56,040 aphids ob ained wi h YPTs and
2488 indi iduals wi h he suc ion ap. The numbe o axa was
83, o which 54 axa could be iden i ied o he species le el and he
emaining 29 axa a a genus le el. A small p opo ion o aphids
(0.3–3.3% pe yea ) could no be iden i ied (Table 1). Se en y- ou
axa we e eco ded in he YPTs, including 23 axa exclusi ely in
hem. On he o he hand, he suc ion ap caugh 61 aphid axa, o
which en axa we e no de ec ed in he YPTs. Ba coding o COI
was done o 34 aphid species (Table S1). Calaphis be ulicola,
C yp omyzus s achydis and Myzus padellus we e ba coded o he i s
ime.
In addi ion, six Aphis gossypii indi iduals ob ained om di e en
ields in 2008-2010 we e ba coded and he COI sequences ound o
be iden ical. They we e and also nea ly iden ical o he 101 Aphis
gossypii COI sequences a ailable in he da abase. They we e clea ly
di e en om o he membe s o he ibe Aphidini, such as Aphis
angulae and Aphis abae included o compa ison (Fig. S1).
Fu he mo e, DNA was isola ed, pooled and he COI ba code
sequence de e mined o an addi ional 30 aphid indi iduals, which
we e caugh om di e en ields in di e en yea s and iden i ied o
Aphis gossypii based on mo phological cha ac e is ics. The sequence
ob ained was iden ical o he sequences o he six indi idually ba -
coded aphids o Aphis gossypii and no double peaks we e obse ed in
he phenog am, indica ing ha mos i no all pooled indi iduals
had an iden ical COI sequence. Taken oge he , hese da a indica ed
ha Aphis gossypii occu ed equen ly in he ield (Table 1).
The spec um o aphid species in he ou yea s was domina ed
by he amily Aphididae, he sub amily Aphidinae and he ibe
Mac osiphini (79%, 75% and 63% o he o al numbe o axa,
espec i ely) (Table 1). Moni o ing o aphids wi h YPTs in he ield
and using he suc ion ap p o ided consis en da a in e ms o he
gene al abundance o aphids in he egion (Figs. 3, 4).
Fu he mo e, he mos abundan species was usually he same in
bo h ap ypes. Fo example, Rhopalosiphum padi domina ed in
YPT ca ches in 2008 and 2009 (22.9% and 29.5%, espec i ely)
and in he suc ion ap in 2007, 2008, and 2009 (33.3%, 47.8%
and 43.9%, espec i ely). Howe e , Hayhu s ia a iplicis was he
mos p e alen species caugh wi h YPTs in 2007 and 2010 (26.2%
and 87.1%, espec i ely), bu was no obse ed in such p opo -
ionally high numbe s in he suc ion ap. O he ag icul u ally
Figu e 2. Clima ic condi ions in he Ty na
¨ a
¨-Liminka a ea in Finland du ing he he mal g owing seasons in 2007–2010. (A) A iew on
a ypical ag icul u al landscape and seed po a o c op. (B) Cumula i e e ec i e empe a u e (T
base
=5uC) and (C) cumula i e p ecipi a ion o e he
he mal g owing seasons. The yea s a e depic ed by solid (2007), dashed (2008), do ed (2009) o do dashed (2010) lines. (D) Compa ison o hou s o
pho osyn he ically ac i e dayligh in h ee impo an seed po a o p oduc ion a eas: Ty na
¨ a
¨-Liminka, Finland (solid line), Ros ock, Ge many (do ed
line), and New B unswick, Canada (dashed line). Ve ical lines in (B) o (D) de ine he po a o g owing season in Ty na
¨ a
¨-Liminka a ea.
doi:10.1371/jou nal.pone.0071030.g002
Phenology o Aphids unde No he n Clima e
PLOS ONE | www.plosone.o g 4 Augus 2013 | Volume 8 | Issue 8 | e71030
Table 1. Rela i e abundance o aphid axa in he suc ion ap (ST) and yellow pan aps (YPT) in Ty na
¨ a
¨-Liminka a ea, No he n
Finland, in 2007–2010.
2007 2008 2009 2010
Li e cycle Clus e ST YPT ST YPT ST YPT ST YPT
To al indi iduals 60 2925 364 6257 961 30013 1103 16845
Acy hosiphon pisum (Ha is, 1776)* m1 B1 1.67 0.67 0.55 0.85 0.10 0.31 0.54 0.60
Acy hosiphon spp. m - - 0.27 - - 0.01 - 0.01
Adelges spp. - - - - 0.21 - --
Ampho opho a ubi (Kal enbach, 1843)* m2 A1 - 0.29 - 1.57 - 0.03 --
Anoecia spp. - - - 0.13 0.10 - --
Aphis abae g oup* h A2 3.33 9.35 1.10 10.61 0.83 8.14 0.27 0.94
Aphis angulae/gossypii complex
1
* h A1 - 0.67 0.55 1.69 - 0.87 -0.23
Aphis idaei an de Goo , 1912* m2 A1 - 2.48 - 2.00 - 1.32 -0.36
Aphis pomi deGee , 1773* m2 A1 1.67 0.76 - 0.66 - 0.08 -0.02
Aphis salica iae Koch, 1855 h - - 1.10 - 1.46 - --
Aphis sambuci Linnaeus, 1758 h A1 - 0.38 - 0.26 - 0.18 -0.02
Aphis spp. hm A1 - 1.81 0.27 2.05 1.25 1.10 -0.63
Aulaco hum solani (Kal enbach, 1843)* h A1 - 0.19 2.75 11.28 0.31 0.36 0.09 0.12
B achycaudus spp. hm B1 - - 0.27 0.08 0.21 0.03 0.27 0.02
Calaphis be ulicola (Kal enbach, 1843)* m2 A2 - 1.34 0.55 0.62 0.42 1.29 0.09 0.13
Calaphis la a Mo d ilko, 1928* m2 A1 - 11.16 - 0.99 2.91 4.80 0.09 0.19
Callip e inella minu issima (S oyan, 1953) m2 - - 0.27 - - 0.01 - -
Capi opho us hippophaes (Walke , 1852)* h B2 - 0.19 - 2.00 0.10 0.44 - 0.06
Capi opho us similis an de Goo , 1915 h A1 - - - 1.15 0.21 1.54 - -
Capi opho us spp. hm - - 0.27 0.08 - - - -
Ca a iella aegopodii (Scopoli, 1763)* h A1 1.67 8.21 0.27 1.15 0.10 0.22 - 0.04
Ca a iella a changelicae (Scopoli, 1763) h A1 - - 0.00 0.03 0.10 0.22 - 0.01
Ca a iella in e media Hille Ris Lambe s, 1969 - - - 0.03 - - - -
Ca a iella konoi Takahashi, 1939* h A1 - - - 0.13 0.52 0.42 0.09 -
Ca a iella pas inacae (Linnaeus, 1758)* h A1 3.33 0.95 0.55 0.89 0.52 4.33 - 0.04
Ca a iella heobaldi (Gille e & B agg, 1918)* h A1 - 0.10 0.27 0.26 - 0.66 - -
Chai opho us spp. m2 A1 1.67 0.10 - 1.98 2.81 13.85 0.18 0.02
Cina a spp. m2 - - - 0.03 0.42 0.00 0.18 0.01
C yp omyzus galeopsidis (Kal enbach, 1843)* h B2 - 13.45 7.14 11.30 2.29 7.24 0.18 3.14
C yp omyzus ko schel i Bo
¨ ne , 1938 h B2 - 0.76 - 0.43 0.10 0.10 - -
C yp omyzus ibis (Linnaeus, 1758) h B2 - 0.76 - 0.16 - 0.05 - 0.06
C yp omyzus s achydis (Heikinheimo, 1955)* h A1 - 0.10 - 0.46 - 0.02 - -
Diu aphis spp. m1 B1 - 1.15 0.27 0.14 0.10 0.14 - 0.13
Dysaphis spp. h
2
B2 - - - 1.50 0.10 0.19 - -
Ela obium abie inum (Walke , 1849)* m2 - - - - 1.77 - - -
Euce aphis spp. m2 A1 5.00 0.48 3.02 0.05 2.50 0.28 90.12 1.55
Eulachnus spp. m2 - - - - 0.10 - - -
Hayhu s ia a iplicis (Linnaeus, 1761)* m1 B1 - 26.15 - 3.64 0.42 6.87 1.54 87.09
Hyalop e us p uni (Geo oy, 1762)* h B2 - 0.10 9.62 0.45 1.25 0.00 0.36 0.10
Hype omyzus lac ucae (Linnaeus, 1758)* h B1 1.67 5.15 1.10 3.36 0.31 1.39 - 0.21
Hype omyzus pallidus Hille Ris Lambe s, 1935 h B2 - 0.19 - 0.21 - 0.02 - -
Li e cycle Clus e ST YPT ST YPT ST YPT ST YPT
To al indi iduals 60 2925 364 6257 961 30013 1103 16845
Hype omyzus hinan hi (Schou eden, 1903)* h B2 1.67 0.10 0.55 0.38 1.04 1.20 0.09 0.04
Hype omyzus spp. hm - - - 0.02 - - - -
Illinoia spp. m
3
-0.10-- ----
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impo an pes species in he YPT ca ch we e Aphis abae (6.3% o
he o al ca ch in 2007–2010), Aphis gossypii (0.8%), Mac osiphum
eupho biae (0.3%) and Myzus pe sicae (0.1%).
Analysis o he numbe s o aphids ob ained wi h he suc ion
ap o e 11 yea s, including he pe iod o his s udy and he
da a a ailable om se en p e ious yea s, e ealed a ecu ing
Table 1. Con .
Li e cycle Clus e ST YPT ST YPT ST YPT ST YPT
To al indi iduals 60 2925 364 6257 961 30013 1103 16845
Mac osiphoniella spp. m1 B1 6.67 0.19 - 0.18 0.10 0.03 0.09 0.05
Mac osiphum eupho biae (Thomas, 1878)* h B1 1.67 1.91 - 0.56 0.21 0.29 - 0.11
Mac osiphum gei (Koch, 1855) m1 - - - 0.03 - - - -
Mac osiphum osae (Linnaeus, 1758)* h A2 - - 1.10 0.05 0.21 0.04 - 0.01
Mac osiphum spp. m
3
---0.02-0.00--
Megou a iciae Buck on, 1876* m1 B1 - - - 0.02 0.10 0.06 0.09 0.11
Me opolophium di hodum (Walke , 1849)* h B1 16.67 3.44 3.30 7.64 1.35 0.88 0.18 0.14
Me opolophium es ucae (Theobald, 1917) m1 - 0.10 - - - - - -
Mic olophium ca nosum (Buck on, 1876) m1 B1 - - - - - - - 0.06
Myzaphis osa um (Kal enbach, 1843)* m2 A1 - - - 0.02 - 0.08 - -
Myzodium modes um (Ho es, 1926) m
4
- - - - 0.21 - - -
Myzus padellus H.R.Lambe s & Roge son,1946* h A1 - - 2.75 1.61 21.12 7.54 0.45 0.31
Myzus pe sicae (Sulze , 1776)* h B1 - - - 0.08 - 0.06 - 0.09
Myzus spp. hm B2 - 0.29 0.82 0.26 0.10 0.03 - 0.01
Nasono ia pilosellae (Bo
¨ ne , 1933) m1 - - - - - 0.01 - -
Nasono ia ibisnig i (Mosley, 1841)* h B1 - 0.19 - 0.05 - 0.04 - 0.02
Pemphigus spp. h
2
---0.060.52---
Pe iphyllus ace is (Linnaeus, 1761) m2 - - - 0.02 - - - -
Pho odon humuli (Sch ank, 1801)* h - - - - 0.10 - - -
P ociphilus spp. h - - - - 0.52 - - -
P o ama spp. m1 B1 - 0.86 - 0.30 - 0.30 - 0.15
P e ocomma spp. m2 A1 - - - 0.18 - 0.20 - 0.02
Rhopalomyzus lonice ae (Siebold, 1839)* h - - 0.27 - - - - -
Rhopalosiphoninus spp. - - - 0.10 - - - 0.01
Rhopalosiphoninus s aphyleae (Koch, 1854) h - - 0.27 - - 0.00 - -
Rhopalosiphum padi (Linnaeus, 1758)* h B2 33.33 1.62 47.80 22.89 43.91 29.45 3.63 0.48
Schizaphis spp. m1 - 0.10 0.27 - 0.21 0.01 - 0.01
Semiaphis spp. hm - - - - - 0.01 - -
Si obion a enae (Fab icius, 1775)* m1 B2 6.67 0.10 5.77 0.02 4.37 0.04 0.54 0.04
Si obion aga iae (Walke , 1848) h 1.67 0.19 0.27 - 0.21 - - -
Si obion spp. hm - - 0.27 - - - - -
Te aneu a ulmi (Linnaeus, 1758) h B2 1.67 0.10 0.55 0.03 0.21 0.00 - 0.01
Thecabius a inis (Kal enbach, 1843) h A1 - - 1.92 0.03 0.73 1.20 0.27 0.09
The ioaphis spp. m1 - - - - 0.21 0.00 - 0.11
The ioaphis i olii (Monell, 1882) m1 - - - 0.02 - - - -
Th ipsaphis cype i (Walke , 1848) m1 A1 1.67 - 0.55 - 1.77 0.06 - 0.02
Th ipsaphis spp. m1 - - 0.55 0.02 - 0.01 - -
U oleucon spp. m1 B1 - 0.86 - 2.21 0.42 1.54 0.09 2.08
Wahlg eniella accinii (Theobald, 1924) m2 5.00 - - - - - - -
o he aphids 3.33 2.96 2.75 1.02 0.83 0.36 0.54 0.33
m
: non hos -al e na ing; possible species comp ise bo h m1 and m2.
m1
: non hos -al e na ing on he baceous hos .
m2
: non hos -al e na ing on woody hos .
h
: hos -
al e na ing.
hm
: no inden i ica ion o species le el. ST: suc ion ap. YPT: Yellow pan ap.
1
mo phological indis inguishable; ba coded indi iduals we e Aphis gossypii
Glo e , 1877.
2
species in his genus a e mos ly hos -al e na ing.
3
species in his genus mos ly non hos -al e na ing.
4
non hos -al e na ing on mosses. *Species u he
cha ac e ised by DNA ba coding; COI sequences a e a ailable in he Ba code o Li e Da a (BOLD) sys ems da abase (h p://www.boldsys ems.o g); accession numbe s
AFNF001-12 o AFNF0039-12.
doi:10.1371/jou nal.pone.0071030. 001
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Figu e 3. Weekly numbe s o winged aphids caugh wi h yellow pan aps (YPT). Aphids we e moni o ed wi h YPTs o e he po a o
g owing season om mid-June o he beginning o Sep embe (weeks 25–36) in Ty na
¨ a
¨-Liminka a ea, Finland, in 2007–2010. Each ba indica es he
o al numbe o aphids ob ained in he gi en week om all ields moni o ed wi h YPTs. The numbe s o ields we e 6 (2007), 7 (2008), 8 (2009) o 4
(2010). The numbe o e e y hi d calenda week is shown below ba s.
doi:10.1371/jou nal.pone.0071030.g003
Figu e 4. Weekly numbe s o winged aphids caugh wi h a suc ion ap. Aphids we e moni o ed wi h he suc ion ap o e he po a o
g owing season om mid-June o he beginning o Sep embe (weeks 25–36) in Ty na
¨ a
¨-Liminka a ea, Finland, in 2007–2010. Each ba indica es he
o al numbe o aphids ob ained in he gi en week. The numbe o e e y hi d calenda week is shown below ba s.
doi:10.1371/jou nal.pone.0071030.g004
Phenology o Aphids unde No he n Clima e
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h ee-yea cyclic pa e n ha was appa en when he excep ionally
high numbe s o Euce aphis spp. caugh wi h he suc ion ap in
2010 we e excluded om da a (Fig. 5).
Phenological cha ac e is ics
A clus e dend og am (Fig. 6) based on YPT da a and no malised
abundance o single species du ing he po a o g owing season
e ealed ha he 51 mos abundan axa used o he analysis ell
in o h ee main phenology clus e s co esponding o ea ly (clus e
A1), mid- e m (B1) and la e (B2) ligh ac i i y. An addi ional smalle
clus e (A2) con ained species showing ligh ac i i y ea ly and la e
du ing he po a o g ow h season (Fig. 7). All clus e s showed high
App oxima ely Unbiased (AU) sco es (.95%).
Among hese 51 analysed axa, 29 axa we e he e oecious (hos -
al e na ing) mo ing om ees/sh ubs o he baceous plan s. Ten
axa we e monoecious (non hos -al e na ing) li ing on he baceous
plan s, and nine axa we e monoecious li ing on ees/sh ubs.
Th ee axa we e iden i ied a genus le el only and canno be
assigned o any o hese li e cycles, because he gene a include
monoecious and he e oecious species. The ea ly and la e ligh
pa e ns we e only se en weeks apa , wi h maximum ligh
ac i i ies being in weeks 27 and 34, espec i ely (Figs. 6,7). The
ea ly ligh clus e s A1 and A2 comp ised eigh monoecious axa
li ing on ees/sh ubs and 14 he e oecious axa. The mid- e m
ligh clus e B1 comp ised eigh monoecious axa, which use
he baceous plan species as hos s, and i e he e oecious axa. La e
ligh ac i i y (B2) was cha ac e is ic o nine he e oecious axa
(Fig. 6).
Aphis spp. and Ca a iella spp. we e ound in clus e A1, excep
Aphis abae ha was loca ed o clus e A2 (Fig. 6). Hype omyzus
species we e ound in clus e s B1 and B2. C yp omyzus was
dis ibu ed o clus e s A1, B1 and B2 depending on species. The
impo an pes s Acy hosiphum pisum, Mac osiphum eupho biae,Me opo-
lophium di hodum and Myzus pe sicae we e placed o clus e B1,
whe eas Si obion a enae and Rhopalosiphum padi occu ed la e and
we e placed o clus e B2 (Fig. 6).
Discussion
In his s udy, seasonal ligh ac i i y o aphids was cha ac e ised
in he no he nmos High G ade seed po a o g owing zone in
Eu ope, in a egion wi h in ensi e ag icul u al p oduc ion. The
majo i y (80%) o he non hos -al e na ing aphid axa on
he baceous hos s we e ound o ha e a p onounced peak in hei
occu ence in he middle o he po a o g owing season, whe eas
90% o he non hos -al e na ing axa on woody hos s showed a
peak o occu ence ea ly in he po a o g owing season. La e-season
ligh ac i i y was cha ac e is ic o he hos -al e na ing species.
Among he ag icul u ally mos ele an aphid species [38] ound
in he a ea, he ce eal aphids Si obion a enae and Rhopalosiphum padi
occu ed la e in he g owing season. Rhopalosiphum padi showed a
dis inc i e monomodal ligh ac i i y in con as o he bimodal
pa e n epo ed in F ance [35] o mul imodal pa e n ound in
No h-cen al pa s o he U.S.A. [39]. These aphid species may
be o mino ele ance as i us ec o s in Ty na¨ a¨-Liminka a ea, in
line o ou p e ious s udy [9], because de elopmen o ma u e
plan esis ance makes po a o plan s less suscep ible o i us
in ec ions owa ds he end o he g owing season [6],[40]. The
abundance o Rhopalosiphum padi in he no he n pa s o Finland is
gene ally lowe and he ligh ac i i y occu s la e han in sou he n
Finland [14],[41] whe e his species is conside ed as one o he
main ec o s o he ba ley yellow dwa i us complex [42] causing
impo an diseases in ce eals [43].
Aphis abae con ibu ed conside ably (6.3%) o he o al YPT
ca ch. This species was cha ac e ised by wo majo ligh pe iods a
he beginning and he end o he po a o g owing season. Po a o
plan s a e mos suscep ible o i us in ec ion a ea ly g ow h s ages
p io o lowe ing [6],[40]. The ea ly ligh ac i i y o Aphis abae
du ing a young g ow h s age o ield c ops in Ty na¨ a¨-Liminka
a ea, he polyphagous na u e o he species, and i s abili y o ec o
mo e han 30 plan i uses, including many non-pe sis en ly
ansmi ed i uses [44],[45], ende s Aphis abae as a po en ial key
pes species in he no he n ag icul u al egion o his s udy.
Indeed, Aphis abae appea s o be he main ec o o Po a o i us Y in
Figu e 5. To al annual numbe o winged aphids caugh wi h a suc ion ap in Ty na
¨ a
¨-Liminka a ea, No he n Finland, in 2000–
2010. Moni o ing was done du ing po a o g owing seasons om mid-June o beginning o Sep embe . Whi e segmen s in s acked ba s depic
p opo ions o Euce aphis spp. Fo he yea s 2000–2002 only da a on o al numbe s o aphids we e a ailable.
doi:10.1371/jou nal.pone.0071030.g005
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po a o c ops in he egion [9]. The snowball ee (Vibu num opulus
L.) is he only known win e hos o Aphis abae in he Ty na¨ a¨-
Liminka a ea [9].
P e ious s udies ha e conside ed Aphis gossypii as a subspecies o
he Aphis angulae complex in Eu ope [26],[46], bu ecen
molecula s udies indica e ha i ep esen s a gene ically
dis inguishable species [47],[48]. S udies on samples om a b oad
geog aphical a ea indica e ha in aspeci ic gene ic a iabili y o
Aphis gossypii is low [33]. No di e ences we e obse ed in he COI
ba code sequences among indi iduals o Aphis gossypii cha ac e ised
in ou s udy, bu hey di e ed om all indi iduals o Aphis gossypii
cha ac e ised om o he coun ies o a leas one nucleo ide
subs i u ion in COI. The e is cu en ly no in o ma ion abou
po en ial p ima y hos s o Aphis gossypii in Eu ope. The e o e,
Eu opean popula ions a e conside ed o be anholocyclic and o
o e win e pa henogene ically in p o ec ed places [38]. This
s udy ound ha in all yea s Aphis gossypii occu ed in no iceable
numbe s (0.8% o he o al ca ch) in he ield, in con as o
p e ious epo s sugges ing ha i occu s exclusi ely indoo s and
should be conside ed as a glasshouse pes only [26],[49]. Ou
esul s sugges ha g eenhouse popula ions a e able o es ablish
well on wild seconda y hos s, e en a in no h in Eu ope.
In a ecen isk assessmen s udy abou alien species in Finland,
Aphis gossypii was anked in he highes ca ego y o po en ial u u e
pes s [50]. I is known o ansmi 75 plan i uses [51] and
colonise mo e han 600 hos plan s [52]. Ou s udy shows ha he
cu en pes s a us o his ex emely polyphagous species needs o
be e-e alua ed. To do his, u he esea ch is needed in o de o
es ablish whe he ac o s such as long dis ance mig a ion o
unknown p ima y hos plan ela ions a e in ol ed in he
popula ion dynamics o his species. In addi ion, in ligh o he
wa ming clima e, i will be essen ial o assess he esponse o his
species o clima ic condi ions in he ield.
In 2010, an excep ionally high p opo ion (90%) o he ca ch in
he suc ion ap consis ed o Euce aphis spp. (Fig. 5; Table 1). A
simila ou b eak o Euce aphis spp. in Finland occu ed in 1988
[53]. Those excep ional abundances we e a ibu ed o long
dis ance mig a ion caused by s ong eas e n wind gus s om
bi ch o es s in Russia and Bela us [53]. Howe e , in YPTs
Euce aphis spp. we e obse ed only in small numbe s (1.5% o he
Figu e 6. Clus e ing analysis o aphid ligh pa e ns. Clus e ing was based on no malised abundance o 51 aphid axa moni o ed wi h yellow
pan aps in a o al o 25 po a o ields du ing ou g owing seasons (2007–2010). Rela i e abundances o aphid species in a gi en calenda week
(column) is indica ed by he sizes o black squa es. Pa e ns we e g ouped using hie a chical clus e ing ‘p clus ’ package in R. App oxima ely
unbiased (AU) p obabili y alues (%) a e shown in he clus e dend og am o he igh . Clus e s wi h AU.95% a e s ongly suppo ed by da a. Li e
cyle codes shown in pa en heses a he end o he species name: h= he e oecious species; m1 = monocious species on he baceous plan s; m2 =
monocious species on ees and sh ubs; hm = no inden i ied a species le el – po en ial species in his genus could be hos -al e na ing o non hos -
al e na ing.
doi:10.1371/jou nal.pone.0071030.g006
Phenology o Aphids unde No he n Clima e
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