Comparative Ultramorphology Of The Proventriculus Bulb Of Two Species Of Mutillidae (Hymenoptera)

4 Pages·1998·1.5 MB·English

by  Flavio Henrique Caetano

OMPARATIVE ULTRAMORPHOLOGY OF THE PROVENTRICULUS
C
BULB OF TWO SPECIES OF MUTILLIDAE (HYMENOPTERA)
Flávio Henrique Caetano ^ ^
Xavier Espadaler ^
FernandoJosé Zara '
ABSTRACT
The proventriculus bulb oftwo species of Mutillidae wasp. Miitilla gliilliauii Spin, and Mynuilla
capitataLucas are studied. The cuticularprojectionson the mobile lips inMiitilla i^hilliaiiii are longerthan
in Myrmilla capitata.
KEYWORDS. Ultramorphology, Proventriculus, Mutillidae, Hymenoptera.
INTRODUCTION
The proventriculus ofinsects is usually considered to be a region connecting the
crop to the stomach. This region may be more orless elaborate according to the feeding
habitsofthe insect, presenting structuresthat may aidboth the Separation offood andits
maceration for later digestion (Chapman, 1975). These auxiliary structures (hairs or
cuticular teeth) are restricted to a region denoted proventriculus bulb which invariably
projects into the crop. These structures in bees helps the Separation of néctar to be
convertedinhoneyfromthepollengrainstobedigested(Snodgrass,1935, 1956). Inants,
theproventiculusbulbactsasabarriertothefoodtobestoredinthecropforshortorlong
periods. The proventriculus bulbofantshas alsobeen used as andementforphylogeny
by EisNER (1957) andTomotake (1997). In social waspsthe bulbconsists offourmobile
lipswithastrongcuticularstructureontheapexofwhichtherearestructureslikeathreads
(Caetano & Machado, 1982; Caetano & Overal, 1984). Its function as filtering
Clements, as is thecase ofotherHymenoptera. InPolistesversicolor(Olivier, 1791) and
Polyhiapaulista (Ihering, 1896) the structures present in the lips are robust and seemto
be related to the process of food maceration rather than filtration, as propose for other
Hymenoptera (Zuben & Caetano, 1994).
1.Dpto.deBiologiaUNESP,CampusdeRioClaro,CEP13506-900SP.Brasil.
2.CentredeRecercaEcológicaIAplicacion.sFore.stals,EdificiC,UniversitätAutónomadeBarcelona,08193.Bellaterra,Spain.
3.CNPq(Processo:401538/90-7)
Iheringia, Sér. Zool.. Porto Alegre, (85): 13.^-136, 27 nov. 1998
134 Caetano; Espadaler &Zara
The aim is to show the variations in the proventriculus bulb in two species of
soHtary wasps ofthe family MutilUdae.
MATERIALANDMETHODS
FivespecimensofMutillaghillianiiSpin, andnineofMyrmillacapitataLucaswerecollectedonthe
campus oftheUniversitätAutónomadeBarcelona, Bellaterra, Spain, where some specimens aredeposited.
The insects were anesthetizedwithethervapor, dissectedin physiological saline, fixed in aqueous
Bouin'sfluidfor 12hoursandthentransferredto70%alcohol. AfterFixation,thecropregionwasdissected
toexposetheproventriculusbulb,whichwasthendehydratedinincreasingbutyricalcoholconcentrations(up
to 100%)for 10minutesandthensubmittedtotwobathsin 100%acetone,eachof10minutesduration.The
material was brought to the criticai point, mounted an 3M metal tape and covered with gold in a Balzer
sputtering.ThemountedmaterialwasexaminedwithaHitachi570SEMat25Kvandphotographsweretaken
with Ilford-HP5-ISO 400/270 film.
RESULTSANDDISCUSSION
Theproventriculus ofMutillaghillianiiandMyrmillacapitata (figs 1-4) shows
differencesinthetwogenera,withM. ghillianii(figs. 1,2)showingmuchlargeramounts
ofcuticularprojections thanM. capitata. InMyrmilla capitata (figs. 3,4) the cuticular
projections are quite reduced both in terms of size and number, and may even be
consideredabsent. Notehow the surface ofthemobilelipis smoothbelow thecuticular
projections.Thisspecieshasnoorificeontheoutersurfaceofthemobilelipimmediately
below the point where the cuticular projections start, which is responsible for the
facilitation ofthe mobility ofthe organ.
The proventriculus bulboíMutilla ghillianii (figs. 1, 2) is similartothatfoundin
ants, ofthe genusMyrmecia, which arethoughttobelongtothe leastderived subfamily
ofFormicidae (Caetano, observed data). As is the case ofMyrmecia, each mobile lip
presentscountlesscuticularprojectionsontheapexandonthesurfacethatfillsthelúmen
of the proventriculus. On the outer surface of each mobile lip there is an orifice
immediately below the site where the cuticular projections start (fig. 1, arrow). In
Myrmecia ants and in Polybiapaulista andPolistes versicolorsocial wasps this orifice
hasbeenassociatedwithfacilitationofthemobilityofthemobilelip.Thismobilitytakes
&
place by action of the longitudinal muscles present in this region (Zuben Caetano,
1994).
Thepresenceoflongitudinalmusclesattachedtothemobilelipwasdescribedby
EisNER (1957) for ants. There are three longitudinal muscle bundles (inner, median and
outer) in the proventriculus neck ofNeoponera villosa (Fabricius, 1804), but did not
propose its association with the mobile Ups movement (Caetano, observed data).
InMutillaghillianiithecuticularprojections measureon average 16.2 \XTaandin
M. capitata 6.6 |im. These data show that inMyrmilla capitata thecuticularprojections
do not function as afilter.
The reduced number and length ofthe cuticularprojections on theproventriculus
bulboíMyrmillacapitatacomparedtoMutillaghillianiisuggeststhegraduallossofthese
structures. This facthas also been noted in ants ofthe subfamily Ponerinae (Tomotake,
1997). Thereductionin sizeandnumberofcuticularprojections maybeinvolvedinthe
Iheringia, Sér. ZooL, Porto Alegre, (85): 133-136, 27 nov. 1998
Comparative ultramoqDhology ofthe proventriculus bulb. 135
90Í63Í 25KV
Figs. 1-4.Mutillaghillianii: 1,proventriculus.Thearrowindicatestheorificeimmediatelybelowthepoint
wheretheprojections Start which isresponsible forlipflexibility; 2, Detail ofthe filiformprojections fully
penetratethe lumen, coveringlarge partofmobile lip.Mynnillacapitata: 3, proventriculus;4, Detail ofthe
apexofamobilelipfromthepreviousfigureshowingthefiliformcuticularprojections.(FP,filiformcuticular
projections; L, lumen; P, reversecropepithelium; PV, proventriculus; S, mobile lips).
Iheringia, Sér. ZooL, PortoAlegre, (85): 133-136, 27 nov. 1998
136 Caetano; Espadaler & Zara
possible alterations ofthe feeding habits ofthese insects along the derivative process.
REFERENCES
Caetano,F.H.&Machado,V.L.L. 1982. MorfologiaehistologiadotratodigestivodeProtopolybiaexigua
e.xigua(Hymenoptera,Vespidae)esuasestruturasexcretorasanexas.PapéisAvuls.Zool.,SãoPaulo34:
283-296.
Caetano, F. H. & Overal, W. L. 1984. Estudos do trato digestivo de vespas (Hymenoptera:Vespidae) e
estruturasexcretoras associadas. I. Morfologia. Revtabras. Ent., SãoPaulo, 28 (4): 403-408.
Chapman, R. F. 1975. Theinsects,structureandfunction. New York, AmericanElsevier. 819p.
EisNER, T. A. 1957. A comparative morphological study of the proventriculus of ants (Hymenoptera;
Formicidae). Buli. Mus. comp. Zool. Harv., Boston, 116: 438-490.
Snodgrass, R. E. 1935. PrincipiesofInsectsMorphology. NewYork, Comstock. 667p.
1956. Anatomyofhoneybee. New York, Comstock. 334p.
.
ToMOTAKE, M. E. M. 1997. Ultra-estrutura do proventrículo de operárias da subfamília Ponerinae
(Hymenoptera: Formicidae). 129p. Tese (Doutorado emZoologia). Instituto de Biociências - UNESP,
Rio Claro. [Nãopublicado].
ZuBEN,C.J.Von&Caetano,F.H. 1994.UltramorfologiadoproventrículodePolybiapaulista(Ihering, 1896)
ePolistes versicolor(Ohvier, 1791) (Hymenoptera: Vespidae). Naturalia, São Paulo, 19: 45-54.
Recebidoem06.04.1998;aceitoem23.07.19
Iheringia, Sér. Zool, PortoAlegre, (85): 133-136, 27 nov. 1998