A preliminary study on the overwintering of Pelopidas mathias (Fabricius) (Lepidoptera, Hesperiidae) in the northern Kanto region, central Japan

2008·0.78 MB·

TThhee LLeepipdiopdteorpoltoegircaollSoocgieitycal Society ooff JJaapapnan
ueLva Trans.Iqi.)iSdo,c.Japan 59(1):23-28,January2008

A preliminary study on the overwintering of Pelqpitla msathias (Fabricius)
(Lepidopt eHreasp,eriidae )in the northern Kanto region, central Japan
[IleLkenaIrNiotJ･E

Department of Furest Entomology, Forestr> a,nd Forest Products Research Institute,
]t･{atsunos a1t,o Tsukuba, Ibaraki ,305-8687 japan; e-mail: [email protected]
Abstract I observed everwintering larva eol' the sinal] brundcd swift, Petopida smathias in
Tsukuba, Ibara kPirefectu rdeurin gthe winter of 2006-2007. Larval density was highest in a sunny
grassla nsdituated by the wa]1 of a buildin gI.n thi senvironment. the larva lfood plant ,Imperata c.vlin-
dric amaintaincd green leave tshroughout the winter, and 1arva wecre active on warm days. Even in
Fcbruar.v ,at an overwintering site thal was exposed to the direc trays of the sun. the daily maximum
temperature sometiines reached approximately 30tC whereas the minimurn fe] 1to near OeC, r.arvae
thaL were collected in thc fiel din early Apri land kcpt in an outdoor cage successful]y dcveloped
and emerged in mid May-early June as adults. Thesc larva meolted zero to threc tirne sbefore pupa-
tion. Thepupal period was 22-35 and 16-21 days when the pupation took place in Apri land May,
respectLvely. Moreover ,one adult femulc was caught by a ]vCalai sterap set in the grasstand near the
buildin ign mid Muy. From the results of thc present study, larvae of P, niathias seem to bc able to
pass the winter in inland field sof the northern Kante region, at ]eas twhen the winter is inild.
Key "'ords Petopidas mathias, 1arva o,veru,intcring, inu]erat ac.ytindriea. diurnal range of temper-
uture, Ibaraki prefectur eeme,rgence season, pupal period,
Introduction
The small branded swift, fetopidas niathias (Fabrici uiss )a ,multivoltine skipper, with hi-
bcrnation occurring durin gthe Iarva lstage. In Japan, the species is resident in southern
Honshu, Shikoku ,Kyushu and the Nansei-Shot oIslands ,and migrants reach northern
Honshu in autumn. It is assumed that P. maihias larvae can pass the winter in the warm
temperate regions of southern Kanto and southward along the Pacifi cOcean (Fukud eat al.,
1984; Shir6zu ,2006). I observed a lot of overwintering larvae during the winter of 2006-
2007 in Tsukuba, an inland city of Ibarak iPrefectur eno,rthern Kanto. Adult emergence
was confirmed by two methods, rearing of larva eand trapping of adult skippers, This paper
reports on the results of these studies.
Materials Methods
and
Laival densit >i'n the.field
I observed everwintering larva eof P. mathias in the fiel dof the Forestry and Forest
Product sResearch Institut e(FFPRI) T,sukuba, Ibaraki Prefecture ,central Japan (36COO'N,
l40008'E ,25 m a.s.1.), from December, 2006 until May, 2007. This fieJ ids ca 45 km away
i]rom thc nearest coast, I chose three sunny grassland ass the study sites. Site A was located
on the south gide of a concrete buildin gand include dtwo quadrat s,The quadrat A-1 (18.5
by O.8 m) abutted the wall and A-2 (18, b5y 4.0 m) was adjacent to A-1. A strip of concrete
(ca i2 cm in width) formed the boundary between A-1 and A-2. There was no pent roof,
but metal tubes existed above quadra tA-1 (Fig s1 and 2) .Sit eB was located between a
pond and a thin pine fores tand include done quadra t(quadr Ba; t18.5 by 4.0 m; Fig. 3).
Sit eC was located on a south slope of a small hil land include done quadra t(quadr aCt;
1 8.5 by 4.0 m; Fig. 4).
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Figs 1-4. Photographs of the site A, B and C on early Febn[ary 2,e07. 1: Site A (quadr Aa-t1 and
A-2) ,PA and PB indica ttehe points where the temperaturcs were recorded. PA (Poin At):
insid tehe grasses growing by the wal1 of a building .PB (Poi nBt): in thc shade of a rree at
1.5 m above the ground .2: A close-up picture of quadra tA-1. 3: Site B (quadr aB)t. 4:
Sit eC (quadra Ct).
Figs 5-6 .A Iai'v naeslt and an overwintering 1arv aof Petopidas mathias found near the building in
early February, 2007. 5: A nest made by an old larvn ,6: A mid insta ]rarva.
At all three of the sites, the gras swas mowed in September of 2006, and after that ,regrowth
appeared. Cogon grass impevata cytindrica (Graminea oene), of the major larva lfbod
plants d,ominated these sites during the winter. I counted the number of P. mathias 1aryae
on grasse sin these quadrat sto determin ethe larva ldensitie sin February ,March, April and
May, 2007, I recorded the daily maximum and minimum temperatures at two point sat site
A (poin At sand B; Fig. 1) from early February unti1 early April ,2007.
Development oflarv aine the spring
[Ib detemine whether overwintered larva ecan complete their developmen tunder outdoor
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Overwintering Petopidas 25
of mathias
conditions, I collected 20 larvae in the fiel dof FFPRI outside the above mentioned quadrats
in early April ,2007. They were reared individual ]iyn transparen tcups (125×125 mm at the
base ,57 mm height )Nfp'hich were placed in a wire-me･sh cage (4 m2×2.5 m in height) in the
fiel d.I ,cylindrica leave swere provide das food . The development of immatures was
2-3days.
checked every
Monitoringofadulit.snthefield

Tb determin ethe adult emergence season of the overwintering generation under natural
conditions, thre eMalaise traps were set along the wall of the buildin gin the grassland near
site A on April 1O, 2007. The traps were checked every week through July 2, 2007,
Results
I found about ten small larva ein early December of 2006 for the fir sttime in quadra tA-1.
On that occasion, the lanJa ldensit ywas unknovLrn. In early Februar yof 2007, 24 larvae of
various sizes were found in quadrat A-1 ([fa b1l, eFigs 5 and 6) ,Most of the larva lnests
were fbund on grasse sgrowing within 10 cm from the building wali, A few larva lnests
were even attached to the walI.
During warm daytimes ,some laiva eemerged from their nests and actively crawled on the
grasse s.In early March and early April ,37 and nine larvae were found in quadrat A-1, re-
spectively. In quadrat sA-2 and B, only a few larvae were fbund in February, March and
April .No larva ewere fOund in quadra tC. In early May, I could not find any larva ein any
of the quadrats .In quadra tA-1, many green regrowths of I. cylindrica live dthroughou tthe
winter (Fi g2,), but in the other quadrat sm,ogt of them died and only a few discolored
leave ssurvived.
The temperatures were higher at poin tA (overwinter siitneg) than at poin tB (ai trempera-
tures: Fig. 7), Even in February ,the dail ymaximum temperature at point A reached ap-
proximatel y300C on sunny days whereas the minimum fel lto near OOC, On cloudy and
rainy days, the difference sin temperature between the two point swere smaller than on
sunny days .No snowfall was observed throughout the winter in and around the present
field.
Table 1. Stat eof food plant sand densiLy of overwintering larvae of P, mathias in each qudrat.
Quadra[ A-l A-2 B C
Area censused (m)18.5xO.8 18.5×4.0 18.5x4.0 18.5x4.0
Season when gras s lat cSeptember. lateSeptembcr,
was inowed in 2006 grass was carriedateSeptemgbrera,s swas carricdmidScptegmbrear,ss was lef tin the grass was lef tin the
outofthgglgEE!lggg-ggLgL!dgtg.fgtllhggs!gng-g !ggE!gug1d 1d -m ptassland
Statc of L cylindrica 20-25 crn in height , 1O-15 cm in heigh t,70-Se cm in height, 40-50 cm in height,
in early February, high densit ym,any high density ,inost highdensity,most lowdensity,most
2007 green regrowths of the regrowths uf thc regrowths of the regrowths
lived died andafew died andafew died andafew
discoloredleaves discolore dleave s discolor eldeaves
suryived survived survivcd
2-9,Feb,24 (1.62) o (o) 2<O.03) O(o)a)
No.1arvae
found(densit1y, ;Mur. 37 (2.50)i･) 1<O.O1) 1 (0,Ol) o (o)
2, Apr, 9 (O.61) 1 (O.Ol) 2 (O,03) o (o)
per m:') 7, May o (o) o (o) o (o) o (o)
:'' One dead larva was found.
o, Two dead larvae were found.
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/4035so6
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i t X. g.e .errToNoN ti tti ttsi ol2i 22Ee6lE ES-ctruSti {{{k. S.g.{t <s ptt s eTc- cl prt - ormr .･ eoc.v ･ eclut lE ccua Tm- o
.L 2' 2 . e t t t tttt 1
Fig .7. Dail ymaximum and miniinum temperatures at points A and B from early February to early
April ,2007.
H
N
H
NHN
/
H
NHN-N
-N
NH-
/
Nk</ma<1tT-tsf9a<rtNts<1aec
'tuE1"zaasEfm>asE1! tstuE1e $coE1tov MdiE1ge c]"1co:7co
Fig. 8.Pupal periods of Pelopidah 'mathias larvae collected ip carly April 2007 under quusi-naturaL
conditions (fie clagde), Each lin ewith symbols denotes an individua] ,Black and white eir-
cles rnean male and female ,respectively. Two larvae which died or escaped wcre excluded.
Tiwent y]arva ecollectcd in the fiel din early April includc dvarious instar s.Eighteen of
them pupatcd in Lhe fiel cdage, Seventee nof them mDlted once or not at all before pupation
and one larv amolted three times ,Pupatio nand adult emergence occurred in early April-
lat cMay and mid May-early June, respectively (Fig 8,) .When the larva epupated in April,
the pupal pcrio dwas 22-35 days, but i twas 16-21 days when the pupatien took place in
May, Males emerged carlie rin the season than females .One female adult was caught in
mid May in the fiel dwith a Malaise trap.
Discussion
In Ibarak iPrefecture ,we can usually observe P, mathias adults from June-Jul >t,o October-
Noyember (Ibara Skhiinbun Co,, 1985; Inoue, 2001, 2007), but the detai losf overwintering
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27
Overwintering of Pelepidas mathias
Table 2. Monthly mean air temperatures (OC )from Oetobe rto April in Mito and Tsukuba (Tateno )I,baraki
Profccture, cenU'al Japan.
OctoberNoi,ember DecemberJanuaryFebruaryMarch April

Av.i, 2006 Av. 2006 Av. 2006 Av. 2007 AN･. 2007 Av, 2007 Av. 2eCL7-..
Mito 15.7 17.I 102 11. 4 S. 1 6.6 2.8 4,6 3.3 5.8 6.3 8.1 1].8 1].6
Tsukuba 15.6 17.3 9.8 11.6 4.5 6.4 2.3 4.S 3.2 6,O 6.5 8.6 12.3 11.9
'' Averas,e of 197I-2000,
of the species in this prefectu rheave not been clarified. In [[bchi gPirefecture ,it is assumed
that migrants lay eggs in June-July and that new generatio nasre produced in summcr-au-
tumn, but that they cannot pass the winter there (Kuzuy a2,000) .From the prescn tobserva-
tions, it seems that larva eof P, mathias are able to pass the winter in inlan dfield s(away
from coastal areas) of northern Kanto, and the emergence of adults successfu11y takes place
in May-June, at leas twhcn the winter is mi'ld.
Larval diapause of P. niathias is terminated by eurly December (Ish i]i98,0), The survival
rate ofP. mathias during winter is lower than that of P. gtttlat aa,nd P. mathias is morc sen-
sitive to low temperature than P, gtttta t(aNakas vate iaL, 1981) .The mean air temperature
at Ibaraki (Mit oand Tsukuba (Taten odu)r)ing the presen tstudy is approximately 2-3 de-
gree sCelsiu shighe rthan the averagc (Mit olocal meteorological observatory; http:!/www,
tokyojma.go.jplhome!mitol) (T.a b2l) e.The mild willter may contribute to successfu1 over-
wintering after termination of diapause .Furthe rstudies are needed to investiga twheether
larva ccan survive normal or cooler winters.
Fukuda et al. (1984 s)peculated that overwintering larvae might be the middle (,th iarndd
fourth) instar sR.esult sof the presen tstudy suggest that the insta rstage of overwintering
larvae is more variable, because iarvae collected in early April molted zero to three times
beforepupation,

Larvae may pass the winter morc easily on grasscs growing near buildings than on those
growing in open land bccause host leaxie skeep a bette rcondition during the winter and the
temperature is higher in such an envirenment. Omeri (1933 p)ointed out a similar result
with the hibernation of the rjce skipper, I'tirnar aguttat a.In lat eautumn and winter, pupae
of the ladybird ,Coccinetla sev)te"ny,ttnctatct bruck ifreguentl yattaches to substances such as
stones or woQd that have been discarde din sunny plaees ,and the heat from warmed sub-
stances makes it possibl efor adults to emerge from pupae even in winter (Sakura teat nali.,
1991; Sakuratan iand Miwa, 2005). Larvae of P. niathias may also develop by receiyins,
heat from warmed substances such as a concrete wall even in mid-winter.
Beck (1 98.3) showed that devclopmenta lresponses to thermopcriods <dai lcyycles of tem-
perature )vary among differe nitnsec tspecies, Jn some cases, developrnenta lperiods are
shortened by thermoperiods (e . Yamashiro et al., 1998), For example, in butterfli ethse,
.o.
dcvelopmenta lperiod (eg gto adult emergence) of IVttratht b{aiznattt sreared under fiuctuat-
ing temperatures was significantly shorter than that under constant temperatures, especially
when the rearing tempcrature conditions were relatively low (As oet al., 2006).
The temperatures recorded in the present study at point A may have been highe rthan those
insid ethe larva lnests which werc made of livin ggras sleaves ,At the overuJintering site
that was exposed to the direc trays of the sun, ho"ieve rP,. mathias Iarvae may have been
exposed to a rather wide range of diurnal temperatures which occasionally reached 30 de-
grees Celsius .In order to understand physiologic aaslpects during hibernation .we must
study the efR]ct of thermoperiods on the Iarva ldevelopmen tof P. mathias in the future,
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Acknow
且edgment
lthank　Ms　K．　Takano　f｛）r　helping　the　experimen1 ，
References
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　　Japanese　with 　EngHsh　sulnlna 巧り．
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　　21st　century 〔2001−2005）．　Ruribosh　i〔35）：2−109（il　lJapanese），
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N　　ak　　asPJtaairl丿nja，ai　nrFa　，1，　8　lg：sluhlti9t，i−　aM1t2a．　5（HL．ieupriado，p1l，　．carnad：　HHe．　sHpoenrdiaid，ae1）918．　LS　urPvoipvuall　aratteis　od　noyfn　aovlernwiinc　toesf　t而hen　gmi　glraar皿vta　，　sckiPphpe．ソrsi　obtu．　tEtceortH，y
OmQri，　N．，1933．　Life　cycle 　of　Parnara　guttat　waith 　special　reference 　to　it　sos・erwintering ．　Dobutsu8aたu．
　　記α∫3’45：303−326（in亅apanese ）．
S　ak　urtaattaa　nbi　JY−i・i．c』ki　ceiunc　hrie】　aKti．　oann　dto　　Ts．o　Ilaork　aa，lt1it9L9［dLe　．S血easPooユl1agl　ecrh，　aLng．e，　C　ihna　amllbgeler　so，f　R　p．　upJ．a，　tDiioxn　oonf　，　CAoc．　cFi、　nG〃e．　a　asnedpt　eImp．　uHncodek−
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摘 要
関東地方北部におけるチ ャバ ネセ セ リ幼虫の 越冬に関する予備的研究（井上大成）
2006−2007年にかけての冬に，茨城県つ くば市で チャ バ ネセ セ リの 越冬幼虫を観察 した．幼虫の密度
は，建物の南1則の壁に近い草地で高かっ た．こ こではチガヤ は冬の 間緑色を保っ てお り，幼虫は暖か
い H 中には活発．に活動 して い た．直射日光の当たる．建物の南側の 越冬場所で は，2月には目最低温度
は〔〕℃ 近くまで ドがっ たが，晴れた 日の最高温度は30℃ 前後に も達した．4月に野外から採集され網
室で飼育された幼虫は．4月上旬一5月下旬に蛹化 し，5月中旬一6月上旬に羽化 した，幼虫は蛹化前に0−
3ま回た脱，皮野外したの。壁蛹際期の 問草は地4に月設に置蛹し化たしマたレ場ー合ズにトはラ2ッ2−3プ5で日はで5．5月月中に旬蛹に化雌し成た虫場1合匹にがは捕1獲6−さ21れ日ただ．っチたャ．
バ ネセセ リは北関東の 内陸で も，少な くとも暖冬の 時には野外越 冬して い るこ とが明らかになっ た．
（Accepted　August　9，2007）
Published　by　thじLepidopterolog［iSooaciety　of　Japan，
5−20，MQtoyokoyama 2，Hachi ji，Tokyo ，192−0063Japan
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