Table Of ContentTThhee LLeepipdiopdteorpoltoegircaollSoocgieitycal Society ooff JJaapapnan
entva Trans.IepidS.oc,Japan 57(4)2:96-300,Septemb2e0r06
Developmental proces sof wing degeneration in the tussock moth Or:gyi raecens
(Htibne(rL)epidopteLryama,ntriidae)
ShuheiNllTsv*
Department of Biologic aSlcience G,raduat eSchoo lof Science sT,okye Metropolit aUnniversity,
Minami-Ohsawa 1-1,Hachieji-shi,192-0397Japan
Abstract The adult female of the tussock moth, Orgyia recens, has vestigial wings. Hewever,
there was no ditleren icne wing deve]opment between sexes until pupation. Even in the beginning
of the pupal stage, female sretained well-developed wing discs as large as those of males. Then the
histulogi ccahalnge of female pupal wing epithelia of this species was observed using light mi-
croscopy. As a result, wing degenerati owans observed in the female wing epitheiiurn jus atfter the
adult differentiati boengan, Phagocytosis was also observed durin gthe wing degenerati oinn the
ccntral larg earea of pupa lwing epithelia. These results strongly suggest that the wing degeneration
of O. recens was caused by programmed cell death.
Key words Pupal wing, wing degeneration ,phagocytosis ,apoptosis, Lymantriidae.
Intreductien
Wing degeneratio onccurs among differe nltineages in Lepidoptera, and certain species of
female moths are wingless, while males of the same species have morphologically and
functionall ynormal wings (Nard eit al,, 1991; Niitsu ,2001, 2003). There is no doubt that
sueh apterous morphs have been secondarily derived from alate morphs in their evolution-
ary histor yb,ecause the loss of wings has occurred independent liyn various insect lsineag-
es. In the tussock moth Orgyia iecens, belongin gto the fymantrii dthaee a,dult males have
normal wings (Fi gI.A). In centrast, the adult female shave vestigial wings (Fi gI,B),
However, both male and female pupae have well-developed wings (Fi g2.) ,Lobbia et al,
(2003 )clarified the precis eendocrinological mechanism of wing degeneratien in O. recens.
They reported that ecdysteroid trigger swing degeneratio nb,ut litt lies known about the his-
tologica lproces sof wing degeneratio inn this species,
In this paper ,I describ tehe proces sof wing degeneration in O. recens, and discus sthe inter-
action of apoptosis and phagocytosi sA.lthough the degeneratio inn the wing size occurs in
both fbrewing sand hind wings, the presen tstudy fbcused only on the fbrewing.
Material sand methods
Cotlectinlgarvae
Larvae of O. recens in various instar swere collected at an apple orchard in Gifu ,Japan.
The larvae were reared on an artificia ldiet fbr Bomb>w mori, All developmenta lstages of
O. recens were maintained under 16h: 8h photoperio d(iig hdta:rk) at 200C. Under these
conditions, pupation occurs 2 days after the onset of wandering in the las tlarva ilnstar.
*Present address: Laborator yfor Evolutionary Morphology .Cente rfor Developmental Biology
(CDB),RIKEN, 2-2-3,Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo, 650-O047Japan
e-mail:[email protected]
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Wing DegenerationinTussockMoth 297
Histological
observations
For histologica lobservations, the wing imagina ldisc sof larva eand pupal wings were re-
moved from their bodies and were fixe dwith Kamovsky's fixtativ e(2% parafbrmaldehyde
+2.5% glutaraldehyd beu)ifere dwith O.IM HCI-sodium cacodylate. They were post-fixed
with 2% osmium tetroxide ,dehydrat eidn a series of ethanol and propylen eoxide, and em-
bedded in Epon 812 (TAAB) ,Semi-thin sections ( 1prn thick )of the wing disc swere pre-
pared on a rotary microtome, mounted on microscopic slides, stained with Azur B, Tissues
on slides were observed using an NIKON OPTIOHOT microscope,
Results
The female of O, recens did not show any symptoms of wing degeneratio bnefor epupatien,
It seemed tha twing disc deyelopment ,tracheatio nprocess ,and cell proliferati porno,gress
in the same way in both sexes until pupatio n(dat naot shown), Even irnmediatel yafter pu-
pation ,the wings of both sexes appeared similar to each other; and the tracheal invasion
into the wing was observed in female wings (Fig ,3A). As soon as adult development
began, as marked by the retraction of wing epithelial cells from their pupal cuticle, the sur-
face area of the female wing began to diminish (Fig 3sB-C).
'Ib
study the deve]opmenta lprocess of O. recens wing degeneration ,I dissecte ddeveleping
wings during early pupal stages and observed the tissu seections, The male wing deyelop-
ment showed normal lepidopter awinng development (Fig 4sA-D), In male wings, immedi-
ately after pupatio n(Day O) and 24 hours after pupation, no morphological changes were
observed (Fig .4A). Forty-eig hhtours after pupation, the male wing epithelium was de-
tached from the sclerotized pupal cuticle (pup aclase) (Fi g4.B). Seventy-two hours after
pupation ,the scales began to elongate from the male wing epithelium, and the wing vein
also began to differentia t(eFi g4.C). Ninety-si hxours after pupation ,the upper and lower
monolayer of the male wing epithelium became closely apposed along their basal surfttces
(Fig 4.D), On the other hand, in female wings, immediatel yafter pupatio n(Da yO) and 24
hours after pupation ,no morphological changes were observed in the cells of the central re-
gions of the pupal wings (Fi g3.A). The wing epithelium was attached tightl tyo the pupal
cuticle (Fi g4,E). The lumen between the upper and lower monolayers was fi11e wdith body
fiui din which a small of number of hemocytes appear. The inneT surface of the wing ep-
itheliu mwas lined with the basal lamina .Forty-eig hhteurs after pupation t,he female wing
epithelium was detache dform the sclerotized pupal cutic]e (pupa clase) (Fi g4.F), Seventy-
two hours after pupation t,he female wings decrease dto two-third of their original size (Fig,
3B) and long scales appeared. Haemocytes became phagocyte sand they also destroye dcel-
lular debris which was thought to originate from wing epithelial cells (Fi g4.G). Ninety-six
hours after pupation, the female wings had degenerated further (Fi g3.C). They decreased
to about one-fifth of their original size and long scales developed (Fi g4.H),
Discussion
I showed that O. recens female pupae have full ydevelope dwing cases and that female
specific wing degeneratio onccurs during early pupa] stages but not during larva lstages.
Phagocytoti fcigure wsere observed in females at 3 and 4 days after pupation .Nardi et al,
(1991 a)lso investigat ethde development of the fernal epupal wings in the wing-reduced
whitemarked tussock moth, O. Ieucostigm au,sing electronmicroscopy, They suggested that
programmed cell death occurs during the adult diiferentia toifo nthe female pupal wings,
but they did not describ ephagocytosis. I speculate that in the case of O. recens, pro-
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Fig,Fi gA,d1u.lts of Ofgyia recens: "'ingless femal eCA) and male (B).
2. Lateral view of pupae of Orgyi arecens. Male (A) und femal e<B) .Arrowhead spoint the
pupal wings.
'
Fig .3. Wings of femal epupa of Org.v ･riecaens in Day O (A) ,Day 3 (B )and Day 4 (C) .The white
arrows point the dista lend of wing epithelium in thc female. Scalc bars: 1mm.
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WingDegeneratien inTussock Moth 299
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Fig, 4, Longitudinal sections of the pupa] wings of Orgyia recens in Day 1 (A) D,ay 2 (B) ,Day 3
(C) .and Day 4 CD) in male. Figure sals oshow in Day 1 (E) D,ay 2 (F) D,ay 3 (G) ,and Day
4 (H) in femalc .c: pupal cuticle; h; hemocyte ;s: scale; t :trachea ;w: wing epithelium,
Arrowheads mdicate cellular debris mgested by hemocytes.
grammed ce]1 death also occurs. In the winter moth, Ar)]ssio dleesfLiari uNsi,its u(2001 )in-
vestigated programmed cel1 death in the pupal wings during the adult dilferentiation.
Female-specif iwicng degeneratio hnas been reported in several other Ocgyia species. In O,
dttbia ,the female has 5-6 larva ljnstar sand the male has 4-5 instar sb,ut the female pupa is
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entirely dif）frecnt丘Qm the male one ；the fbmale pupa is‘‘vermi 食）rm ” with no wing buds and
the female adult is apterous （wingless ）（Mosta ね and Laila 1969）． In O．吻 θ伽 α the fe−
， ，
Inale wings show seasonal dimorphsm． That is the fbmale autumn adults have short wings ，
while the female summer adults have normal wi，ngs （Sato，1977）． Since Org卿 is a genus
containing many brachypterous（short wing ）species and apterous （wingless ）females， wing
degeneratio onf female sis genera lwithin the genus．
However the molecular and celular mechanisms causing the female−specific winglessness
，
are not yet understood ． In the only report of Lobbia et al．（2003）， they have demonstrated
血at female−specific wing degeneration in O ． recens is induced dlrect lbyy ecdysteroids
（20E and E）in pupal wing culture． However the fin eendocrinological basi sof the wing
，
degeneratio rnemains un own ．
Acknowledgements
1 thank Mr K． Yamada （Shiga）for his kind help in collecting materials ． My thanks are also
due to Dr S． Lobbia（Universit oyf Tokyo）， and Miss T． Kawashima （Universit oyf Tbkyo）
fbr their rearing materials ．1謡so thank Professo rY Kobayashi of Tokyo Metropolitan
Universit fyor many suggestions and critica1 reading of the manuscript ．
References
Lobbia， S門Niits， uS． and H． Fujiwara，2003． Female−specific wing degeneration caused by ecdysteroid in the
Tussock Moth ，0アg卿 rθcθπ∫：Hormonal and development arlegulation of sexual dimorphism．孟傭 θα
Sci，3：1−7，
Mostafa， H ． and E． S． Laila，1969． On the bionomic sof Orgyiaぬわia judae aSTGR （Lepidoptera，
Lymantriida）．e Bull．∫oc ． e砿 Eg）”pte 53：161−183．
N a rdic，os」t．i gBma．， Go（dLe仕peiyd， oGp．t Le，r Laanydm aRn． tAri． dBae）re． gJs．t Mroormp，1ゐ9．9210， 9：P1r2o1g−r1a3m1m．ed cell death in the wing ef Orgyia leu−
Niitsu， S．，2001． Wing degeneratio ndue to apoptosis in the femal ewinter moth Nyssiodes lefualius
（Lepodopter， aGeometrida）e． Ent． Sci．4：1−7
moth，， 2E0”0m3e，taP voasriteegamtbaryo（nLiec pdiedvoepltopemr， ePansty Gofh itdhea） e，wiノng：1吻 iψma海gi．2na517 ；di1c6s4 −i1n 7t0h，e femal ewingless bagworm
Sato， T、，1977， Life history and dispose of the white −spotted tussock 皿 oth ， Orgyia thyellina Buder
（Lepodoptera， Lymantriidae）．’αρ訊 卿 ’． E庶 Zoo’21 ：6−14（in Japanese with English summary ）
摘 要
ア カモ ン ドクガ （鱗翅目，ドクガ科）における翅退化プロ セ ス （新津修平）
アカモ ン ドクガ雌の翅は痕跡翅を持つ 程度まで翅が退化してい る．しかしながら観察の結果 蛹になる
までの翅原基の発生過程に雌雄で差は見られなかっ た．蛹期の初期の段階において も，雌では雄と同じ
くらい 良く発達した翅を有してい た．そこで，雌蛹における翅膜上皮組織の組織形態の変化を調べ るた
めに，光学顕微鏡観察による切片の観察を行っ た．その結果，アカモ ン ドクガの雌蛹では，成虫分化開始
後に翅膜上皮が退縮してい くのが観察された．退縮時におい て，翅膜上皮中央部の広い範囲で，血球
細胞による食作用が観察された．この ことからアカモ ン ドクガ雌の成虫分化における翅退縮は，プロ グ
ラム細胞死に よる現象で あるこ とが強 く示唆された．
（Aocepted March 11，2006）
Published by the Lepidopterologica lSociet yof Japan，
5−20，Motoyokoyama2，Hachij，iTokyo，192−0063Japan
〔’
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