Ballooning of spiders (Araneae) in Switzerland: general results from an eleven-year survey

2009·0.19 MB·English

by  Blandenier, G

308 Bull.Br.arachnol.Soc.(2009)14(7),308–316
Ballooning of spiders (Araneae) in Switzerland: Farmlands are unstable and unpredictable environ-
general results from an eleven-year survey ments. A high dispersal ability is important for spider
populationswhichliveinarablefieldsinorderforthem
Gilles Blandenier to survive in such habitats. In agroecosystems, the
CentreSuissedeCartographiedelaFaune(CSCF), important role played by spiders has been thoroughly
PassageMax-Meuron6, discussedbyNyffeler&Sunderland(2003).Itisimport-
CH-2000Neuchâtel,Switzerland ant to have a good understanding of ballooning disper-
sal when studying the local distribution of species and
Summary the colonisation of newly created habitats (e.g. sown
wildflower strips in agricultural landscapes).
A survey of ballooning spiders was carried out over a
Weyman(1993)andWeymanetal.(2002)studiedthe
periodofelevenyearsbetween1994and2004.Altogether,
causative factors responsible for initiating ballooning in
15,398 ballooning spiders, representing 103 species and 16
families,werecaughtwitha12.2mhighsuctiontrapinan spiders. For these authors ‘‘the incidence of ballooning
agriculturallandscapeofSwitzerland.ThefamiliesLinyphi- is probably best viewed probabilistically, with shift in
idae, Araneidae, Philodromidae and Theridiidae were probabilityattributabletolifestage,genderandphysio-
numerically dominant. Linyphiids represented 60% of the
logical state (e.g. hungry, gravid)’’. Bonte et al. (2003a)
total, and were the most diverse family. Of the total
also pointed out the importance of the genetic back-
captures, 31% were adults, and 52% of the adults were
females. The diversity of species caught as males (78) was ground of the species and the type of habitat for
higherthanthatoffemales(68). initiating ballooning behaviour. Furthermore, these
Weobserved11speciesfrequentlyballooning:Meioneta authors (Bonte et al., 2003b) tested the initiation of
rurestris, by far the most frequent, Araeoncus humilis,
ballooning behaviour in spiders under laboratory con-
Erigone dentipalpis, Porrhomma microphthalmum, Erigone
ditions, and found that habitat specialists from frag-
atra,Tenuiphantestenuis,Nucteneaumbratica,Bathyphantes
gracilis, Eperigone trilobata, Mangora acalypha and mented landscapes are characterised by poorly
Oedothoraxapicatus.Ofthe103speciesrecorded,28species developed dispersal behaviour. Finally, in a given
(27%)andtwogenerahadnotpreviouslybeenrecordedin species, the proportion of individuals initiating balloon-
ballooning studies, and 22 species are rare in Switzerland.
ing varies between populations depending on the land-
Although the proportions of species from open areas and
scapeconfiguration(Bonteetal.,2006).Theproportion
fromareaswithbushesandtreeswerealmostidentical,the
proportion of individuals of species from open areas was ofindividualsthatdisplayedtiptoebehaviourwaslower
muchhigher;46%wereground-livingspeciesandtheothers in offspring originating from a small and extremely
werefromhighervegetationlayers. isolated patch than among those from larger habitat
Dispersalbyballooningshowedtwomainpeaks:thefirst
patches.
between the end of May and mid-August and the second
Theaimofthisstudywastoinvestigatewhichfamilies
from the beginning of October until the beginning of
November. The maximal diversity was found in June (34 and species can be found ballooning in a fragmented
species). The percentage of adults varied between 12 and agricultural landscape and to determine the long term
65%duringtheyear.Thepercentageofadultfemalesvaried phenologypatternsofballooningtaxa.Theseresultsare
between 32 and 100%. Phenological patterns for the main
a continuation of the work first published a decade ago
familiesarepresented.
(Blandenier&Fürst,1998).Datafromthesametrapfor
the year 1993 were analysed in the work of Stebler &
Introduction
Nentwig (1999). Evolution patterns of the taxa and
Dispersalbyballooningisawell-knownbehaviourof links with ground-level data will be analysed in further
spiderswhichhasalsobeenobservedinspidermitesand papers.
in larvae of moths. Recently, important reviews of this
phenomenon have been published (Bell et al., 2005;
Material and methods
Weyman et al., 2002). Ballooning, although it is not the
only dispersal behaviour, confers on spiders high col- Airborne spiders were collected with a Rothamsted
onisation abilities. Indeed, in newly created habitats, Insect Survey suction trap (Taylor & Palmer, 1972;
spidersareamongthefirstcolonisingorganisms(Meijer, Derron&Goy,1987).Inthistrap,samplingofairvaries
1977; Sugg & Edwards, 1998). between42and43m3/min.Spiderscaughtataheightof
Ballooning in spiders can either be achieved by the 12.2m are automatically collected in small bottles con-
‘‘suspendedballooning’’methodwhichisfoundinmany taining 70% ethanol. This trap was the same as the one
primitive spiders or initiated by the behaviour called used in Blandenier & Fürst (1998).
‘‘tip-toe’’ in most araneomorph groups (Bell et al., The trap was located at the research station
2005). In this last behaviour, the opisthosoma is raised Agroscope ACW Changins-Wädenswil in the western
in the air and silk is extruded from the spinnerets. On region of the Swiss Plateau (in Changins, Canton de
entering the air column, wind drag pulls on the silk and Vaud, 6(14#0$E, 46(24#8$N, 440m a.s.l.). It was
when lift is sufficient, the spider becomes airborne. situated within cultivated areas (mainly wheat, barley,
Thedurationandconsequentlyheightandlengthofthe rape, corn, sunflowers, beans and grapes), near a small
passive flight(s) will depend on meteorological con- fallow area. Some patches of semi-natural areas were
ditions. Reynolds et al. (2007) showed that balloon- present within this agricultural landscape (forests,
ing arthropods select meteorological conditions which hedgerows, wetlands, dry grasslands, small rivers), also
maximise dispersal. urban zones and a large lake (Lake Geneva).
G.Blandenier 309
Adult spiders were determined to species, and imma- Females (52%) were slightly more numerous than
ture specimens to family or genus level. Some juveniles males, but the diversity of males (78 species) was
and penultimate instar individuals were identified to higher than that of females (68). However, among the
species where possible, including some Araneidae, Linyphiidae, the most abundant family, females were
Thomisidae, Lycosidae, Theridiidae and regionally more numerous than males.
monospecifictaxa.Thiswasalsosupportedbycompari- Thefollowing11speciescanbeconsideredasfrequent
son with local land captures. ballooning species (recorded in more than 10% of the
The data were collated by week for the eleven years 519 weeks): Meioneta rurestris, Araeoncus humilis,
from 16 April 1994 until 31 December 2004. The trap Erigone dentipalpis, Porrhomma microphthalmum,
was not operated in winter at the beginning of the Erigone atra, Tenuiphantes tenuis, Nuctenea umbratica,
survey, during the periods 17 December 1994 to 17 Bathyphantes gracilis, Eperigone trilobata, Mangora
March1995and3December1995to17March1996.It acalypha and Oedothorax apicatus. Meioneta rurestris
wasstoppedformaintenancebetween12February1998 wasbyfarthemostfrequentspecies(63%oftheweeks).
and21April1998.Exceptduringtheseperiods,thetrap For A. humilis, B. gracilis, E. atra, M. rurestris, P.
was operated continuously. This represented a total of microphthalmum and T. tenuis, there were more females
519sampledweeks.Inordertosynchronisetheweeksof caught than males. Eighteen species showed frequencies
each year, two days, 29 February and 31 December, between10%and2%,and74wererare(frequency<2%)
were dropped from the calendar. In consequence, we ballooning species. Twenty-two species (21%: Table 2)
have two weeks of eight days. have been rarely recorded in Switzerland (<11 records).
During the study the mean temperature was 10.8(C With respect to ecology, ground-living species were
and the mean annual precipitation 1091mm (data from dominant (46% of all species caught, 5% were from the
the MeteoSwiss station of Changins, Swiss Federal herbaceous layer, 26% from the herbaceous and trees
Office of Meteorology and Climatology). and bushes layers, 13% from the trees and bushes layer,
Knowledge of the Swiss spider fauna is based on and 10% were species inhabiting various layers.
publications by Maurer & Hänggi (1990) and Hänggi Half (51%) of the species live in open habitats, the
(1993, 1999, 2003) and, for ground-living species, data remainderinhabitatswithbushesandtrees.Individuals
published in Blandenier & Derron (1997), Freuler et al. of species from open areas were caught much more
(2001), Derron & Blandenier (2002) and Derron & frequently (80%) than those from the other habitats.
Blandenier (2006). Among the latter group, only 18% were ground-living
Ecological classification of the species was based on species, the others being from higher strata. Of the
the data of Hänggi et al. (1995) and of the author, and species living in open habitats, the majority were from
was done to identify the major habitat categories of meadows and fields. Eight species were associated with
spiders.Thehabitattypegivenherecanbeconsideredas dry meadows and two with wetlands. Three species
the place where we have the highest probability of weretobefoundontrees,rocksorbuildingsandonein
encounteringaspecies.Habitattypesgroupareaswitha caves and rocky places. Eleven immature spiders
similar structure. The stratum gives information about were parasitised by external larvae of Hymenoptera.
theplace(inaverticalsense)wheretheadultspiderlives These were 6 Araniella sp., 4 Theridiidae sp. and one
for most of the time. Linyphiidae sp.
Sinceourlastpublication(Blandenier&Fürst,1998),
thenamesofsomegeneraandfamilyclassificationhave
changed. Here we use the nomenclature of Platnick
Families No.species Individuals %
(2005).
(ad.+imm.) (ad.+imm.) Total
Linyphiidae 44 9283 60.29
Araneidae 11 3005 19.52
Results
Philodromidae 7 1339 8.70
Theridiidae 11 555 3.60
Species and ecology
Lycosidae 4 360 2.34
Atotalof15,398spidersrepresenting103speciesfrom Thomisidae 4 315 2.05
16 families were caught between 1994 and 2004. Four Tetragnathidae 3 233 1.51
Salticidae 9 141 0.92
families represented more than 90% of the captured
Clubionidae 3 61 0.40
individuals: Linyphiidae (60% of the total), Araneidae,
Anyphaenidae 1 32 0.21
Philodromidae and Theridiidae (Table 1). Overall, 31% Corinnidae 25 0.16
of the individuals were adults (Table 2). Of the 103 Dictynidae 4 17 0.11
species, 98 were caught as adults and/or immatures, Miturgidae 1 16 0.10
and five species were represented only by immatures Gnaphosidae 1 6 0.04
Agelenidae 1 0.01
(Table 2).
Dysderidae 1 0.01
Five families (Linyphiidae, Araneidae, Theridiidae,
Undetermined 8 0.05
PhilodromidaeandSalticidae)madeup80%ofthetotal Total 103 15,398 100.0
numberofspecies.TheLinyphiidaewasthemostdiverse
family. Three families (Agelenidae, Corinnidae, Dysde-
Table1: Number of spider species and individuals collected, by
ridae) were represented only by immatures. family.
310 BallooningspidersinSwitzerland
Family Species _ \ imm. Total %Tot. F K Ry St. Ecol.
Agelenidae Agelenidaesp. 1 1 0.01 0.2 **
Anyphaenidae Anyphaenaaccentuata(Walckenaer,1802) 9 2 21 32 0.21 5.6 * W T TBU
Araneidae Aculepeiraceropegia(Walckenaer,1802) 1 42 43 0.28 5.2 * W H M
AraneusdiadematusClerck,1757 2 4 6 0.04 1.0 * W HT TBU
Araneussturmi(Hahn,1831) 4 1 5 0.03 1.0 X W HT TBU
Araneustriguttatus(Fabricius,1793) 1 1 0.01 0.2 * W T TBU
Araneussp. 11 11 0.07 1.5 **
Araniellaalpica(L.Koch,1869) 1 1 0.01 0.2 X W HT TBU
Araniellacucurbitina(Clerck,1757) 1 1 2 0.01 0.4 X W HT TBU
Araniellaopisthographa(Kulczyn´ski,1905) 19 4 23 0.15 3.1 * W HT TBU
Araniellasp. 332 332 2.16 39.3 **
Argiopebruennichi(Scopoli,1772) 2 2 0.01 0.4 * W H M
Gibbaraneasp. 12 12 0.08 2.1 Y
Larinioidessp. 19 19 0.12 1.3 **
Mangoraacalypha(Walckenaer,1802) 1 125 126 0.82 16.8 * W HT M
Nucteneaumbratica(Clerck,1757) 5 661 666 4.33 26.8 * W T TBU
Zygiellax-notata(Clerck,1757) 39 8 47 0.31 6.9 * W T BRTBU
Zygiellasp. 138 138 0.90 9.4 **
Araneidaesp. 1571 1571 10.20 32.4 **
Clubionidae ClubionabrevipesBlackwall,1841 9 1 10 0.06 1.9 * W HT TBU
ClubionadiversaO.P.-Cambridge,1862 1 1 0.01 0.2 X W HT M
Clubionapallidula(Clerck,1757) 2 1 3 0.02 0.6 X W HT TBU
Clubionasp. 47 47 0.31 8.5 **
Corinnidae Phrurolithussp. 25 25 0.16 2.5 *
Dictynidae Argennasubnigra(O.P.-Cambridge,1861) 5 5 0.03 0.4 * W G DM
Dictynaarundinacea(Linnaeus,1758) 1 1 0.01 0.2 * W HT M
DictynapusillaThorell,1856 2 2 0.01 0.4 X W HT TBU
Lathyshumilis(Blackwall,1855) 4 1 5 0.03 1.0 * R HT TBU
Dictynidaesp. 4 4 0.03 0.8 **
Dysderidae Dysderidaesp. 1 1 0.01 0.2 **
Gnaphosidae MicariasubopacaWestring,1861 2 2 0.01 0.4 X R T TBU
Gnaphosidaesp. 4 4 0.03 0.8 *
Linyphiidae Araeoncushumilis(Blackwall,1841) 260 446 706 4.59 44.3 * W G MFI
Bathyphantesgracilis(Blackwall,1841) 78 81 159 1.03 20.2 * W G OA
Bathyphantesparvulus(Westring,1851) 1 1 0.01 0.2 X R G WF
Centromeritabicolor(Blackwall,1841) 1 1 0.01 0.2 * W G OAFI
Cinetatagradata(Simon,1881) 1 1 2 0.01 0.4 * R GHT F
Collinsiainerrans(O.P.-Cambridge,1885) 3 3 0.02 0.6 * R* G FI
Dicymbiumnigrum(Blackwall,1834) 1 1 0.01 0.2 * W G M
Diplostylaconcolor(Wider,1834) 4 12 16 0.10 3.1 * W G F
Entelecaracongenera(O.P.-Cambridge,1879) 1 1 0.01 0.2 X W HT TBU
Eperigonetrilobata(Emerton,1882) 138 81 219 1.42 17.3 * R* G M
ErigoneatraBlackwall,1833 139 219 358 2.32 35.1 * W G OAFI
Erigonedentipalpis(Wider,1834) 282 251 533 3.46 41.8 * W G OAFI
Gnathonariumdentatum(Wider,1834) 3 3 0.02 0.6 * W G M
LepthyphantesnodiferSimon,1884 1 1 0.01 0.2 * W G F
LinyphiahortensisSundevall,1830 2 2 0.01 0.2 X W H F
Masosundevalli(Westring,1851) 1 1 0.01 0.2 X W G F
Meionetamollis(O.P.-Cambridge,1871) 16 12 28 0.18 4.6 * W G OAFI
Meionetarurestris(C.L.Koch,1836) 535 693 1228 7.98 63.4 * W G OAFI
Meionetasimplicitarsis(Simon,1884) 18 16 34 0.22 5.8 * R G DM
Micrargussubaequalis(Westring,1851) 4 4 8 0.05 1.2 * W G MFI
Microlinyphiapusilla(Sundevall,1830) 4 1 5 0.03 0.8 X W H M
Microlinyphiasp. 60 60 0.39 7.5 **
Micronetaviaria(Blackwall,1833) 3 3 0.02 0.6 X W G F
Moebeliapenicillata(Westring,1851) 4 2 6 0.04 1.2 * R GHT F
Obscuriphantesobscurus(Blackwall,1841) 1 1 0.01 0.2 X W GHT F
Oedothoraxapicatus(Blackwall,1850) 85 36 121 0.79 14.5 * W G OAFI
Oedothoraxfuscus(Blackwall,1834) 12 9 21 0.14 3.7 * W G MFI
Osteariusmelanopygius(O.P.-Cambridge,1879) 3 3 6 0.04 1.2 * R G FI
Palliduphantesarenicola(Denis,1964) 2 2 0.01 0.4 X R G DM
Panamomopssulcifrons(Wider,1834) 1 1 0.01 0.2 X W G M
Pelecopsisparallela(Wider,1834) 4 8 12 0.08 2.1 * W G MFI
Porrhommamicrophthalmum(O.P.-Cambridge,1871) 246 295 541 3.51 39.3 * W G OAFI
Porrhommaoblitum(O.P.-Cambridge,1871) 8 25 33 0.21 5.4 * W G M
PseudomaroaenigmaticusDenis,1966 2 2 0.01 0.4 * R SO C
Tenuiphantesflavipes(Blackwall,1854) 6 3 9 0.06 1.5 * W G F
Tenuiphantesmengei(Kulczyn´ski,1887) 1 1 0.01 0.2 * W G F
Table2: Listofspeciesandhighertaxacollected,withpercentagesoftotal,frequency,previousknowledgeofballooning,rarityandecological
information.Abbreviations:_=adultmales;\=adultfemales;imm.=immatures;F=numberofweeksrecorded,expressedaspercentage
oftotal519weeks;K=previousknowledgeofballooning:*=speciesknowntoballoon,**=highertaxaknowntoballoon,X=speciesnot
recorded ballooning, Y=higher taxa not recorded ballooning; Ry=rarity (based on Swiss data): R%11 records, R*%11 records but
expanding its range, W>11 records; St.=stratum: SO=soil, G=ground-living, H=herb layer, T=trees and bushes; Ecol.=ecology:
C=cavesandrockyplaces,M=meadows,O=openareas,F=forests(>30%canopycover),FI=fields,D=drymeadows,BR=buildings
(androcks),W=wetlands,BU=bushes,T=trees.
G.Blandenier 311
Family Species _ \ imm. Total %Tot. F K Ry St. Ecol.
Tenuiphantestenuis(Blackwall,1852) 105 140 245 1.59 27.7 * W G OA
Tenuiphanteszimmermanni(Bertkau,1890) 1 1 0.01 0.2 * W G F
Tisovagans(Blackwall,1834) 1 1 0.01 0.2 * W G M
Trematocephaluscristatus(Wider,1834) 4 4 0.03 0.8 * W GHT F
Trichopternacito(O.P.-Cambridge,1872) 2 2 4 0.03 0.8 * W G DM
TroxochrusnasutusSchenkel,1925 2 2 0.01 0.4 * R GHT F
Walckenaeriaantica(Wider,1834) 1 1 0.01 0.2 * W G OA
Walckenaerianudipalpis(Westring,1851) 1 1 0.01 0.2 * W G M
Walckenaeriavigilax(Blackwall,1853) 8 9 17 0.11 3.1 * W G OAFI
Linyphiidaesp. 4878 4878 31.68 75.7 **
Lycosidae Arctosasp. 1 1 0.01 0.2 **
Auloniaalbimana(Walckenaer,1805) 1 1 0.01 0.2 * W G MFI
Pardosaagrestis(Westring,1861) 1 1 0.01 0.2 * W G FI
Pardosabifasciata(C.L.Koch,1834) 1 1 0.01 0.2 X W G DM
Pardosaproxima(C.L.Koch,1847) 6 6 0.04 1.2 * R G M
Pardosasp. 350 350 2.27 26.6 *
Lycosidaesp. 11 11 0.07 1.7 **
Miturgidae CheiracanthiummildeiL.Koch,1864 1 1 2 0.01 0.4 * R T TBU
Cheiracanthiumsp. 14 14 0.09 2.3 **
Philodromidae Philodromusaureolus(Clerck,1757) 33 12 45 0.29 5.2 * W HT TBU
PhilodromusbuxiSimon,1884 2 2 0.01 0.4 X R HT TBU
Philodromuscespitum(Walckenaer,1802) 7 7 0.05 1.3 * W HT TBU
PhilodromuscollinusC.L.Koch,1835 3 3 0.02 0.6 * W HT TBU
PhilodromusdisparWalckenaer,1826 1 1 0.01 0.2 * W HT TBU
PhilodromuspraedatusO.P.-Cambridge,1871 1 4 5 0.03 0.8 * R HT TBU
PhilodromusrufusWalckenaer,1826 50 17 67 0.44 7.7 * W HT TBU
Philodromussp. 1209 1209 7.85 65.3 **
Salticidae Balluschalybeius(Walckenaer,1802) 1 1 0.01 0.2 X W GHT F
Carrhotusxanthogramma(Latreille,1819) 1 1 0.01 0.2 * W T TBU
Heliophanussp. 2 2 0.01 0.4 Y
Phlegrafasciata(Hahn,1826) 1 1 0.01 0.2 * W GHT M
Pseudeuophryslanigera(Simon,1871) 2 2 0.01 0.4 * R* GHT BRTBU
Pseudiciusencarpatus(Walckenaer,1802) 2 1 3 0.02 0.6 X R GHT TBU
Salticusscenicus(Clerck,1757) 2 1 3 0.02 0.6 * W HT BRTBU
Salticuszebraneus(C.L.Koch,1837) 30 3 33 0.21 4.2 * W T TBU
Salticussp. 13 13 0.08 1.7 **
Talaveraaequipes(O.P.-Cambridge,1871) 1 1 0.01 0.2 X W G DM
Talaveraaperta(Miller,1971) 7 7 14 0.09 1.5 X R GHT DM
Salticidaesp. 67 67 0.44 9.6 **
Tetragnathidae Metellinasp. 8 8 0.05 1.3 **
PachygnathadegeeriSundevall,1830 13 20 33 0.21 4.6 * W G MFI
Pachygnathasp. 64 64 0.42 4.2 **
TetragnathamontanaSimon,1874 2 2 0.01 0.4 X W H W
TetragnathaobtusaC.L.Koch,1837 1 1 0.01 0.2 X W HT TBU
Tetragnathasp. 125 125 0.81 16.2 **
Theridiidae Anelosimusvittatus(C.L.Koch,1836) 6 2 8 0.05 1.3 * R T TBU
Anelosimussp. 3 3 0.02 0.6 **
Keijiatincta(Walckenaer,1802) 7 1 8 0.05 1.5 * W T TBU
Neottiurabimaculata(Linnaeus,1767) 1 1 0.01 0.2 * W GHT OA
Paidiscurapallens(Blackwall,1834) 2 2 4 0.03 0.8 * W T TB
Robertusarundineti(O.P.-Cambridge,1871) 29 19 48 0.31 7.7 * W G M
Robertuslividus(Blackwall,1836) 2 2 0.01 0.4 X W G F
Robertusneglectus(O.P.-Cambridge,1871) 1 1 0.01 0.2 * W G FI
Robertussp. 4 4 0.03 0.8 **
Steatodaphalerata(Panzer,1801) 4 4 0.03 0.6 X W G M
Steatodasp. 5 5 0.03 1.0 **
TheridionboesenbergiStrand,1904 3 3 0.02 0.6 * R HT DM
TheridionimpressumL.Koch,1881 12 3 15 0.10 2.5 * W HT TBU
TheridionmystaceumL.Koch,1870 3 1 4 0.03 0.8 X R T TBU
Theridiidaesp. 434 434 2.82 13.5 **
Thomisidae Diaeadorsata(Fabricius,1777) 22 5 27 0.18 4.4 * W HT TBU
Diaeasp. 108 108 0.70 14.3 **
Misumenavatia(Clerck,1757) 1 1 0.01 0.2 * W HT M
Synemaglobosum(Fabricius,1775) 5 5 0.03 1.0 * W HT M
Xysticusaudax(Schrank,1803) 1 1 2 0.01 0.4 X W G F
Xysticussp. 66 66 0.43 9.2 **
Thomisidaesp. 106 106 0.69 12.7 **
Undetermined 8 8 80 0.05 1.2
Total 2326 2505 10,567 15,398
Speciesnumbers 78 68
%ad. %tot.
males 48 15
females 52 16
immatures 69
Table2: Continued.
312 BallooningspidersinSwitzerland
Fig.1: Generalphenologyofallspiderscollectedperweek.Numbersofspecies,andtotalsofadultfemales,adultmalesandimmatures.
Phenology were synchronised, the first peaks were not: the peak
of species richness came before the peak of abundance.
Ballooning by spiders occurred almost throughout The highest number of species (34) was observed in
the whole year, with reduced activity in winter from June.
the beginning of December until the end of February The first ballooning peak of the season consisted
(Figs.1and2).Themaximalnumbersofspiderindivid- mainly of immatures (Fig. 1). The main ballooning
ualswererecordedballooninginlatespringandsummer activityofimmatureslastedforsixmonthsbetweenlate
betweentheendofMayandmid-August.Asecondpeak May and early November. The ballooning activity of
ofballooninglastedfromthebeginningofOctoberuntil adults was clearly bimodal, this being caused by adults
the beginning of November. ofthemostfrequentfamily(Linyphiidae).Thefirstpeak
The number of species ballooning also showed two (from the beginning of June until mid-September: three
peaks: the first in May–June, the second in October. andahalfmonths)lastedlongerbutwasslightlysmaller
Whilst the second peaks of individuals and species than the second peak (from the beginning of October
Fig.2: Generalphenologyofallspiderscollectedperweek.Proportionsofeachfamily;totalnumberofindividuals=15,390.
G.Blandenier 313
until the end of November: two months). This second becausedbylargenumbersofasingletaxon,whereasin
peak of adults accounts for the second overall peak in other years, one peak may be completely suppressed.
numbers ballooning. Thisinter-annualvariabilitywillbeanalysedindetailin
Adults comprised 31% of the total sample, but this a later paper.
proportion varied considerably throughout the year
(Fig. 3). It was highest at the beginning of the year
Discussion
(exceptionally reaching 100% in January, in a week of
lowcaptures),untiltheendofMarch,andattheendof The 12.2m high suction trap is a good standardised
theyear,fromthebeginningofOctober.Thereweretwo method for the study of ballooning because it works
periods with a low proportion of adults, in April and in continuouslyandautomaticallyoveralongperiod.This
September. From May to August, the percentage of method is used in most European countries to study
adults was close to the overall average (between 23 and aphid dispersal (Euraphid European project). It has
39%). been used to study ballooning dispersal of spiders in
Among adults, the ballooning of males began and England(Sunderland,1987,1991;Thorbeketal.,2002),
ended a little earlier than that of females during both Denmark (Toft, 1995) and Germany (Volkmar et al.,
peakperiods.Theproportionoffemalescapturedvaried 2004a,b).Someoftheseauthorscomparedthistrapping
between32and100%oftheadults,andwashigherthan method with other methods. The height of the trap was
that of males for 67% of the weeks: from January until chosen to be ideal for aphids so that catches of aphids
the end of April, between July and the beginning were independent of populations in the immediate
of September, and from mid-October until the end surroundings.Adisadvantageofthemethodforspiders
of the year. The percentage of females was below 50% is that aerial dispersal is also made by a succession
in May and June and from mid-September until of small flights near the ground (Thorbek et al., 2002;
mid-October. Toft, 1995). A 12.2m high suction trap cannot provide
In the phenology of families (Fig. 2), Linyphiidae information about such low-level ballooning.
represented more than 50% of the catches for 40 weeks At a height of 12.2m, individuals are caught in flight
oftheyear.ThispercentagewaslowerfromMarchuntil fromunknowndistancesanddirections.Arecentmodel
May. Araneidae were caught mainly in late spring and by Reynolds et al. (2007) shows that the distance of a
summer. Philodromidae were numerous in spring, and flight is less than a few hundred metres for the majority
ballooning activity lasted until the end of November. of ballooners, but that for some, distances of tens or
Theridiidaewerenevernumerous,butwerecaughtfrom even hundreds of kilometres are possible.
spring until the end of November. Lycosidae were Allfamiliescaughtinthisstudyarealreadyknownto
caught from March until mid-April and in late summer balloon,andallthemostabundantoneshaveoftenbeen
andearlyautumn.Thomisidaewerecaughtinspring,at cited in ballooning studies (Bell et al., 2005). The
the beginning and end of the summer, and at the Linyphiidae, with 60% of the total, is the most import-
beginning of autumn. The available data do not show ant family. Other authors found a percentage between
any clear pattern for the other families. 63and97%inEurope,butlowerintheUSA(Nyffeler&
The general pattern of phenology presented here Sunderland, 2003). Two reasons could explain the high
varied between the years. In some years, one peak may percentage of Linyphiidae captures. First, this family is
Fig.3: Changesinpercentagesofadultandimmaturespidersthroughouttheyear.
314 BallooningspidersinSwitzerland
strongly dominant in agroecosystems of the northern- camefromhabitatswithtreesandbushes.Themajority
temperate zone of Europe. In the surroundings of our ofthesespeciesliveintheseupperstrataformostofthe
trap, at ground level, the Linyphiidae are the most time. This shows that ballooning is also often used as a
diverse family and one of the most active. Secondly, dispersal strategy by this group of spiders, as has been
according to Bell et al. (2005), the propensity for bal- pointedoutforshrubsbyEhmann(1994).Itisclearthat
looning dispersal is much higher in this family than in under favourable meteorological conditions it is quite
others. There is also a correlation between the relative easyforthesespeciestoreachplaceswhereitispossible
abundanceofLinyphiidaeintheairandontheground, to initiate ballooning. We caught only nine ground-
as shown by Thomas & Jepson (1999). For the other living‘‘forest’’species.Forthesespeciestoo,ballooning
families,theintensityofballooningdoesnotnecessarily dispersal is possible, but appears to be rare.
reflecttheirrelativeabundanceinthearea.Forexample, Ballooning dispersal occurs throughout the year, but
we observed 24 species of Gnaphosidae, some of which is less frequent in winter. At that time, low ground
are frequent at ground level as shown by pitfall traps in surfacetemperaturesreducebothspideractivityandthe
thisarea.Inthesuctiontrapwecaughtonlyaverysmall low-level thermal updraughts needed for ballooning.
number of individuals, suggesting that ballooning at a This is particularly the case when persistent fog covers
height of 12.2m is fairly rare in this family and that the studied area. The first peak was mostly due to
their dispersal ability is probably weaker than in other immaturesofdifferentfamiliesandthesecondtoadults,
families. although there were also numerous immatures present
The 103 species we caught represent 11% of the during the second peak. This pattern of dispersal
known Swiss spider fauna (Hänggi, 2003), and 36% of was first noted by Bristowe (1939) and confirmed by
the known fauna of the local area based mainly on Sunderland(1987).Volkmaretal.(2004a,b)alsofound
pitfall trap data (CSCF database 6.07). This number maximum numbers of captures in July. Unsurprisingly,
adds 43 species to the first report of this study which in our area, diversity is maximal in June for both
ended in April 1997 (Blandenier & Fürst, 1998). The ballooningspidersandground-livingspiders(e.g.Duelli
relatively high number of apparently rare species et al., 1990).
recorded (22, =21%) might be explained by the lack of Thepercentageofadultswashighestatthebeginning
baseline data on their habitats. This is particularly true andattheendoftheyear,whentherewerefewcaptures,
forthe15speciesinhabitingstrataabovethegroundand andlowestinAprilandSeptember.Airbornespidersare
herbaceous layers. Furthermore, Eperigone trilobata, moreoftenimmatureinstars,asshownhereandinother
Collinsiainerrans,OsteariusmelanopygiusandPseudeuo- populationstudies.Volkmaretal.(2004a,b)mentioned
phryslanigerawererareuntil1990andarenowexpand- a mean of 62.5% of immatures, which is similar to our
ingtheirrangesinSwitzerlandandelsewhereinEurope, value. Sunderland (1991) found 43% of immatures,
afactthatcanbepartlyexplainedbytheirhighcolonis- but indicated that this percentage is normally between
ation ability due to ballooning. Eperigone trilobata 40 and 70%. However, at certain periods of the year,
is considered as an alien species in Switzerland particularlyinlateautumn,winterandspring,adultscan
(Wittenberg, 2005). This species, which was one of the form the major part of ballooning spiders, as observed
11mostfrequentballoonersinourdataset,hashitherto byDuffey(1956,1998).Thispatternfollowsthegeneral
rarely been mentioned in ballooning studies. Most of agestructureofthepopulationsinthesehabitats.
our frequent ballooning species were also common in The observed sex-ratio, slightly biased towards
other studies (Bell et al., 2005). Nuctenea umbratica has females, reflects that of the most frequent family, the
rarely been mentioned as ballooning, and Mangora Linyphiidae. For 67% of the weeks the percentage of
acalyphaisreportedhereasballooningforthefirsttime, females was higher than that of males. Here too,
but this behaviour has been reported in other Nearctic maxima were observed at the beginning and end of the
and Holarctic species of the same genus (Bell et al., year. Only twice did the percentage of females drop
2005). We caught immatures of these last two species in below 50%: in May and June and from mid-September
large numbers. It is therefore possible that, in other until mid-October. Regarding the number of species, a
studies, they were not identified to species level. higher diversity of males was recorded than for females
To our knowledge, based on the review of Bell et al. (78/68). As shown by Duffey (1956), the proportion of
(2005) (with additions by Komposch & Natmessnig ballooning by both sexes depends on the species. The
(2001)forTroxochrusnasutus andBenzetal.(1983)for percentage of females is higher among common grass-
O.melanopygius),28species(27%)andtwogenerafrom land aeronauts (Linyphiidae). The observation that
our list have never previously been mentioned as more females ballooned could be attributable either to
ballooning (Table 2). intrinsic gender differences or to indirect effects of
Dispersalbyballooningisusuallydescribedasbehav- physiological state on nutritional requirements and dis-
iour typical of spiders from open, unstable habitats. At persal probability (Weyman et al., 2002). For Bonte
ground level in forests, there is little chance for convec- et al. (2003a), the biased sex-ratio during ballooning in
tive currents to create sufficient drag for ballooning the field cannot be attributed to differences in tiptoe-
dispersal (Bell et al., 2005). In our study, the number of initiating behaviour, because that is identical in males
individuals from open areas was much larger than that and females.
fromareaswithtreesandbushes.Regardingthenumber The phenology of ballooning dispersal of both sexes
ofspecies,itisinterestingtonotethatabouthalfofthem was seasonally synchronised during the year. However
G.Blandenier 315
the peaks of male ballooning began and ended a little arachnological material and for technical assistance. Dr
earlier than those of females. This is consistent with Marie-France Cattin, Dr Jacques Derron, Dr Yves
previousobservationsbyThomas&Jepson(1999),who Gonseth, Odile Burgisser, Prof. Louis-Félix Bersier
also showed that the dispersal peak occurs earlier for and anonymous reviewers made useful comments. Dr
males than for females. Edward Mitchell corrected the English text.
The ballooning dispersal of adults is strongly linked
with reproduction, as a means of searching for a mate
and/or dispersing the progeny. According to Duffey References
(1998) this dispersal behaviour could be a physiological
BELL, J. R., BOHAN, D. A., SHAW, E. M. & WEYMAN, G. S.
response of adults, perhaps especially of females,
2005:Ballooningdispersalusingsilk:worldfauna,phylogenies,
irrespective of other stimuli. For Plagens (1986), bal- geneticsandmodels.Bull.ent.Res.95:69–114.
looning is an effective means for males to search for BENZ,G.,NYFFELER,M.&HUG,R.1983:Osteariusmelanopy-
females,whileThomas&Jepson(1999)suggestthatone gius (O. P.-Cambridge) (Aran. Micryphantidae) neu für die
Schweiz. Über ein Massenauftreten der Spinne in Zürich und
goal of the aerial dispersal of females is to spread the
dieZerstörungderPopulationdurchSchneefall.Mitt.schweiz.
risk of reproductive failure by laying egg sacs in several ent.Ges.56:201–204.
patches. This hypothesis is supported by the fact that BLANDENIER,G.&DERRON,J.O.1997:Inventairedesaraignées
ballooningdispersalcanbefrequentinmatedfemales,at (Araneae)épigéesdudomainedeChangins.RevuesuisseAgric.
least in some species (Weyman et al., 2002). 29(4):189–194.
BLANDENIER,G.&FÜRST,P.-A.1998:Ballooningspiderscaught
Most adult linyphiid spiders show two periods of
byasuctiontrapinanagriculturallandscapeinSwitzerland.In
aerial dispersal, linked to the fact that they have two
P.A.Selden(ed.),Proceedingsofthe17thEuropeanColloquium
generations of adults per year. This was shown in ofArachnology,Edinburgh1997:177–186.BritishArachnologi-
BelgiumforErigoneatrabyDeKeer&Maelfait(1988). calSociety,BurnhamBeeches,Bucks.
Adult linyphiids contribute largely to the second peak BONTE,D.,DEBLAUWE,I.&MAELFAIT,J.-P.2003a:Environ-
mentalandgeneticbackgroundoftiptoe-initiatingbehaviourin
late in the season. For Toft (1995), summer ballooning
thedwarfspiderErigoneatra.Anim.Behav.66:169–174.
dispersal has the potential for long-range migration
BONTE, D., VANDENBROECKE, N., LENS, L. & MAELFAIT,
between breeding habitats, while spring and autumn J.-P. 2003b: Low propensity for aerial dispersal in specialist
movements may have evolved as short distance migra- spiders from fragmented landscapes. Proc. R. Soc. Lond. (B)
tions between breeding and hibernation habitats in 270:1601–1607.
BONTE,D.,VANDENBORRE,J.,LENS,L.&MAELFAIT,J.-P.
Denmark. However, in agreement with Thorbek et al.
2006:Geographicalvariationinwolfspiderdispersalbehaviour
(2002), we observed that aerial dispersal at or above a isrelatedtolandscapestructure.Anim.Behav.72:655–662.
height of 12.2m is also fairly important in late autumn, BRISTOWE,W.S.1939:Thecomityofspiders1:1–228.London,Ray
suggesting that ballooning spiders can also show long- Society.
range dispersal at this time. It is possible that, further DE KEER, R. & MAELFAIT, J.-P. 1988: Observations on the life
cycleofErigoneatra(Araneae,Erigoninae)inaheavilygrazed
south in Europe, meteorological conditions may be
pasture.Pedobiologia32:201–212.
more favourable for ballooning in autumn than in the
DERRON,J.O.&GOY,G.1987:Utilisationdespiègesàaspiration
north. According to Thorbek et al. (2002), the duration pourlaprévisiondesépidémiesdevirus.RevuesuisseAgric.19:
of conditions allowing ballooning is shorter in autumn 129–132.
than in spring and summer. This second phase of DERRON,J.O.&BLANDENIER,G.2002:Typologiedescarabes
etdesaraignéesdudomainedeChangins.RevuesuisseAgric.
ballooning dispersal could also be important for move-
34(4):177–186.
ments between fields and for the recolonisation of
DERRON,J.O.&BLANDENIER,G.2006:Evolutiondespeuple-
agroecosystemsaftermostagriculturalinterventionsare mentsdecarabesetd’araignéesdanscinqtypesd’habitatsdu
over. According to Weyman et al. (2002), individuals domainedeChanginsde1994à2001.RevuesuisseAgric.38(3):
of the genus Erigone inhabiting arable farmland have 141–149.
DUELLI,P.,STUDER,M.&KATZ,E.1990:Minimalprogramme
the capacity to balloon at any time of the year and at
fürdieErhebungundAufbereitungzooökologischerDatenals
any phenological stage. However, they do not express
Fachbeiträge zu Planungen am Beispiel ausgewählter Arthro-
this tendency constantly. Therefore, ballooning by podengruppen.SchrReiheLandschaft.Natursch.32:211–222.
spiders inhabiting arable farmland is not confined to a DUFFEY,E.1956:Aerialdispersalinaknownspiderpopulation.J.
particular season or to a particular sub-set of the Anim.Ecol.25:85–111.
DUFFEY,E.1998:Aerialdispersalinspiders.InP.A.Selden(ed.),
population.Theobservedphenologicalpatternsarethus
Proceedings of the 17th European Colloquium of Arachnology,
the consequence of various factors (physiological
Edinburgh 1997: 187–191. British Arachnological Society,
stresses, meteorological conditions) that trigger and BurnhamBeeches,Bucks.
allow ballooning. EHMANN,W.J.1994:Organizationofspiderassemblagesonshrubs:
anassessmentoftheroleofdispersalmodeincolonization.Am.
Midl.Nat.131:301–310.
Acknowledgements FREULER, J., BLANDENIER, G., MEYER, H. & PIGNON, P.
2001: Epigeal fauna in a vegetable agroecosystem. Mitt.
This study was funded by grants from the Centre schweiz.ent.Ges.74:17–42.
Suisse de Cartographie de la Faune (CSCF) and from HÄNGGI, A. 1993: Nachträge zum ‘‘Katalog der schweizerischen
the research station Agroscope ACW Changins- Spinnen’’–1.Neunachweisevon1990bis1993.Arachnol.Mitt.
6:2–11.
Wädenswil. We thank Dr Jacques Derron, Gabriel Goy
HÄNGGI, A. 1999: Nachträge zum ‘‘Katalog der schweizerischen
and their colleagues at the research station of Changins
Spinnen’’–2.Neunachweisevon1993bis1999.Arachnol.Mitt.
for giving us the opportunity of working on their 18:17–37.
316 BallooningspidersinSwitzerland
HÄNGGI, A. 2003: Nachträge zum ‘‘Katalog der schweizerischen SUNDERLAND,K.D.1991:Theecologyofspidersincereals.Proc.
Spinnen’’–3.Neunachweisevon1999bis2002undNachweise 6thInt.Symp.Pests+DiseasesofSmallGraincerealsandMaize
synanthroperSpinnen.Arachnol.Mitt.26:36–54. (Halle/Saale,Germany)1:264–280.
HÄNGGI, A., STÖCKLI, E. & NENTWIG, W. 1995: Habitats of TAYLOR,L.R.&PALMER,J.P.1972:Aerialsampling.InH.F.
Central European spiders. Miscellaneae Faun. Helveticae 4: van Emden (ed.), Aphid technology: 189–234. London,
1–460. AcademicPress.
KOMPOSCH, C. & NATMESSNIG, I. 2001: Ein Massenauftreten THOMAS, C. F. G. & JEPSON, P. C. 1999: Differential aerial
der Zwergspinne Troxochrus nasutus in Kärnten. Carinthia II dispersal of linyphiid spiders from a grass and a cereal field.
191:497–516. J.Arachnol.27:294–300.
MAURER, R. & HÄNGGI, A. 1990: Katalog der schweizerischen THORBEK, P., TOPPING, C. J. & SUNDERLAND, K. D. 2002:
Spinnen.Doc.faun.helv.12:1–412. Validationofasimplemethodformonitoringaerialactivityof
MEIJER,J.1997:Theimmigrationofspiders(Araneida)intoanew spiders.J.Arachnol.30:57–64.
polder.Ecol.Entomol.2:81–90. TOFT, S. 1995: Two functions of gossamer dispersal in spiders?
NYFFELER, M. & SUNDERLAND, K. D. 2003: Composition, Naturajutl.70:257–268.
abundanceandpestcontrolpotentialofspidercommunitiesin VOLKMAR, C., SCHLIEPHAKE, E. & LANDFELD, K. 2004a:
agroecosystems: a comparison of European and US studies. MonitoringdesSpinnenfluges-AuswertungvonSaugfallenfän-
Agric.Ecosyst.Envir.95:579–612. gen(2000bis2003)amStandortAschersleben.DGaaE-Nachr.
PLAGENS, M. J. 1986: Aerial dispersal of spiders (Araneae) in a 18(3):85–86.
Floridacornfieldecosystem.Envir.Ent.15:1225–1233. VOLKMAR, C., SCHLIEPHAKE, E. & LANDFELD, K. 2004b:
PLATNICK,N.I.2005:Theworldspidercatalog,version6.0.<http:// ZurVerbreitungsstrategievonSpinnen(Araneae)inmitteldeut-
research.amnh.org/entomology/spiders/catalog/index.html> schen Agrarraum. Mitt. biol. BundAnst. Ld-u. Forstw. 396:
REYNOLDS,A.M.,BOHAN,D.A.&BELL,J.R.2007:Ballooning 192.
dispersal in arthropod taxa: conditions at take-off. Biol. Lett. WEYMAN,G.S.1993:Areviewofthepossiblecausativefactorsand
Doi:10.1098/rsbl.2007.0109.4pp. significance of ballooning in spiders. Ethol. Ecol. Evol. 5:
STEBLER, D. & NENTWIG, W. 1999: Upper limits of body length 279–291.
andweightforaeronauticactivityinadultandimmaturespiders WEYMAN,G.S.,SUNDERLAND,K.D.&JEPSON,P.C.2002:A
(Araneae)incultivatedlandinSwitzerland.Unpublishedthesis, review of the evolution and mechanisms of ballooning by
UniversitätBern,23pp. spiders inhabiting arable farmland. Ethol. Ecol. Evol. 14:
SUGG,P.M.&EDWARDS,J.S.1998:PioneerAeoliancommunity 307–326.
developmentonpyroclasticflowsaftertheeruptionofMount WITTENBERG, R. (ed.) 2005: An inventory of alien species and
St.Helens,Washington,U.S.A.Arct.alp.Res.30(4):400–407. their threat to biodiversity and economy in Switzerland. CABI
SUNDERLAND, K. D. 1987: Spiders and cereal aphids in Europe. Bioscience Switzerland Centre report to Swiss Agency for
IOBC/WPRSBull.10:82–102. Environment,ForestsandLandscape.