Description of the eggs of Curicta bonaerensis (Heteroptera: Nepidae)

4 Pages·2001·2.8 MB·

by  Ruf, Mónica Lopez

ISSN 0373-5680Rev.Soc.Entomol.Argent. 60(1-4):69-72,2001
Description of the eggs of Curicta bonaerensis
(Heteroptera: Nepidae)
LOPEZRUFfMonica* y PabloJ.PEREZ GOODWYN**
*DepartamentoCientificode Entomologia,Museode LaPlata,PaseodelBosque.1900LaPlata,Argentina;
e-mail:[email protected]
**InstitutodeLimnologia"Dr. RaulA.Ringuelet",CC 712.1900LaPlata,Argentina;
e-mail:[email protected]
• ABSTRACT. Eggsare described based upondirectobservation and scanning
electron micrographs. Eggs bear 12-13 respiratory horns forming a crown
each one ending in aplastron structure,which continues insidethem and deve
lops under the chorion. Three micropyles and acomplex chorionic hydropyle
arefound. Aeropyles are found on alloverthe surface of the eggson the tip of
tubercles, scattered all overthe surface of the eggs,excepton the hydropyle, in
side the horn crown, and in a beltsurrounding it. The morphology of the eggs
of this species fits the descriptions given for other Nepidae. The egg laying
habitof this species isendophytic, abehaviorthatwas thoughtto be restricted
to Ranatrinae genera.
KEYWORDS. Egg.Chorion. Heteroptera. Nepidae. Curicta.
• RESUMEN.Descripcion de los huevos de Curicta bonaerensis(Heterop
tera: Nepidae). Los huevos estan descriptos sobre la base de la observacion
directa y las fotografias del MEB. Seobservaron entre 12 y13 cuernos res
piratorios formando una corona, cada uno de ellos finalizando en una es
tructura de plastron, en el pedunculo secontinua por dentro y sedesarrolla
por debajo del corion. Seencontraron tres micropilos y un hidropilo corio
nico complejo. Seobservaron aeropilos en el extremo de tuberculos distri
buidos en toda la superficie de los huevos, excepto en el hidropilo, dentro
de la corona y del cinturon que la rodea. La morfologia del huevo de esta
especie coincide con la de las descriptas para otros Nepidae. El habito de
postura esendofitico, conducta aparentemente restringida a los generos de
Ranatrinae.
PALABRAS CLAVE. Huevo. Corion. Heteroptera. Nepidae. Curicta.
INTRODUCTION this family isscarce, particularly regarding Neotro
pical taxa (Wiley, 1924;McPherson & Packauskas,
Two Nepidaegenera are recorded from Argen 1987; Keffer et al., 1994), even though there
tina: Ranatra Fabricius, and Curicta Stal, the for are excellent general works (Cobben, 1968;
mer one with seven species, the latter with four. Hinton, 1961,1969). Description of chorion
Curictabonaerensis(Berg)isasmall waterscorpion through SEM was carried out on Naucoridae,
usually found in low number, inhabiting Buenos Belostomatidae, and European Nepidae (Baker,
Aires and Entre Rlos provinces, as well as Uru 1987; Lopez Ruf,1989; Wichard et al.,1995;
guay (Keffer, 1996; Bachmann, 1998). Sites & Nichols, 1999). Eggs of Curicta, based
on C. bonaerensis are described here for the
Literatureconcerningeggsand laying habitsof first time.
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Rev. Soc.Entamal. Argent. 60(1-4),2001
MATERIAL AND METHODS RESULTS
Specimens of C. bonaerensis were collected in Egg description. Subeliptical with a subapical
Punta Lara(EnsenadaDistrict, BuenosAires provin crown of 12 to 13 plastron-bearing horns (Fig. 1).
ce) in a permanent water body around 500 meters With an aft of the posterior pole- a circular hy
awayfrom the shoreofthe RiodelaPlata(34°47'5; dropyle (205 - 216 urn) (Fig. 2). Light brown
58° 01' W). The areasampled was usuallycovered when alcohol fixed, white when recently laid.
by floatingvegetation and shaded by adenseforest. Surface granulose when observed through light
Mature eggswere taken from dissected fernale binocular stereoscope. Range: Length excluding
oviducts (N= 8) and from endophytic eggslaid in horns: 1.52 - 1.56 mm, width: 0.54 - 0.52 rnm
laboratory (N= 3). Adult specimens were kept in (ovarian eggsmeasured).
500 cm3 containers with Spirodela sp. (Lernna
ceae) assubstraturn. Material was extracted from Horns. 51ightly tapered towards their blunt
ethanol fixed females and since the eggs were apex. Range: Length: 0.86 - 0.97 mrn (Fig. 3),
slightly collapsed, they were placed in glacial width near plastron: 17.20urn.Apical respiratory
acetic acid for a few minutes. They were then plastron (Fig. 4) developed on about 1/3 of the
kept in Bouin fixing fluid in order to keep their horn length (362.16 - 378.37 urn), The plas
original shape. Eggswere rinsed with an ultraso tron-bearing portion is slightly thicker than the
nic cleaner for 15 minutes submerged in amixtu restofthe horn. Plastron consists in ahighly per
%
re of 70% ethanol, 20<XJ ethyl acetate, and 10 forated surface. The margin of each hole isslightly
benzene. Finally they were metalized with elevated and serrated looking like a"crater" (ho
gold-palladium and observed with the Scanning lediameter:0.86- 1.39urn) (Fig. 5).Towardsthe
Electronic Microscope ofthe Museo de LaPlata. apex anasthornosis of holesgivesthe surface aspect
Fig.1:Egg generalview, insertedinleaf.Scale:1.5mm Fig. 2:Hydropyle.Scale: 100urn
Fig. 3:Horns,generalview. Scale: 100urn Fig. 4: Horns, detail of the beginning of the plas
tron-bearingportion.Scale:50/-lID
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LOPEZRUF,M.andP.PEREZ GC)ODWYN. DescriptioneggsCurictabonaerensis
Fig. 5:Plastron,detail.Scale:5J.1m Fig. 6: Transverse section of horn through plastron
portion.Scale: 10urn
Fig. 7:Transversesectionofhornthroughportionwit Fig. 8:Micropyles.Scale: 100um
houtplastron.Scale: 10urn
Fig. 9:Chorionsurface,detail.Scale:50urn Fig. 10: Transverse section of chorion with bifurcate
aeropyleandunderlyingplastron.Scale: 10urn
of trabecules. Shown in transverse section (plas communication (horn wall thickness: 4.54 J.1m,
tron thickness: 3.30J.1m) (Fig. 6) the plastron ho core approximate diameter: 14.60J.1m) (Fig.7).
les communicate to the inner part of the horn
where a meshwork is developed, described as Chorion. Immediately below the horn crown a
"core" by Hinton (1961) for Nepa cinerea Linne. tubercle bearing three micropyles (Fig. 8) isobser
A section through the part of the horn without ved. Shortly below the micropyles, the chorion is
plastron shows that the meshwork continues covered with tiny tubercles (approximately 5 J.1m
along the core of the horn without any external high and 6.45 - 8.60 J.1m wide), each one located
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Rev. Soc.Entomol. Argent. 60(1-4),2001
on the centre of the track of the follicular cell (ap ACKNOWLEDGEMENTS
proximatediameter15.00- 23.60urn) bearingthe
aeropyles (Fig. 9). Some aeropyles are bifurcated We are grateful to Dr. A. O. Bachmann, Dr. A.
(Fig. 10). Intransverse section the plastron (12.40 L. Estevez and Prof. M. Perez Goodwyn for their
12.80 urnthick) is developed under the chorion helpful comments on the'manuscript.
(4.00 - 5.00urnthick) (Fig.10). No aeropyles were
observed inthe centre ofthe horn crown (diarneter:
23.43 urn) and immediately under it (a belt about LITERATURECITED
108 urn wide) (Fig.8).
Some endophyticeggsofC. bonaerensisdepo BACHMANN, A. O. 1998. Heteroptera acuaticos.
sited by females in laboratory were observed in In:MORRONE, j. j. & S.COSCARON (eds.), Biodi
Spirodela sp. as substratum. When laid, onlvthe versidad de Artr6podos Argentinos, Ediciones
horn crown isseenandtheeggaxisisslightlytilted, Sur,LaPlata, pp. 163-180.
thus allowing the crown to be parallel to the floa BAKER, G. T. 1987. Morphology of the chorion of
ting line (Fig.l). The aeropylezone beginsdiagonal Belostoma lautariurn (Stal) (Hemiptera: Belos
totheegg longitudinal axis, possiblyfollowingthe tomatidae). Bull. Zool. 54: 229-231.
floating line and the plant epidermis. It is worth COBBEN, R.H.1968. EvolutionarytrendsinHeteropte
noticingthat this water plantwas the onlyavaila ra.PartI.Eggs/ architecture ofshell;grossembryo
ble substratum for the female to lay itseggs. logyandeclosion.Wagenigen, TheNetherlands.
HINTON, H. E.1961.The structureand function of
the egg-shell in the Nepidae (Hemiptera). }.
DISCUSSION Ins. Physiol. 7: 224-257.
HINTON, H. E.1969. Respiratory systems of insect
Hinton (1961) described the eggsof several ne egg shells. Ann. Rev. Ent. 14: 343-368.
pid species and concluded that the structure and KEFFER, S.L.1996. Systernatics of the new world wa
numberof respiratory horns could beuseful for ge terscorpion genusCurictaStal(Heteroptera: Nepi
nera identification, even though he found striking dae).). NewYorkEntomol.Soc.104(3-4):117-215.
variations between speciesand even between indi KEFFER, S.L.,S.S.TAYLOR, & j. E.MCPHERSON. 1994.
viduals. Eggs of C. bonaerensis borne 12 to 13 Laboratory rearing and description of inmature
horns, very similarto thoseof N. cinerea, exceptfor stagesof Curicta scorpio(Heteroptera:Nepidae).
theslightwideningoftheplastron-bearingportionof Ann. Entomol. Soc. Am. 87(1): 17-26.
the horn that wasfound in C.bonaerensis. No ano LOPEZ RUF, M. L.1989. Loshuevos dealgunasespe
malous horns were found probably due to the few cies de losgeneros Pelocoris y Ambrysus (Hete
eggs observed. Hinton (1969) described different ropteraLirnnocoridae). Limnobio«2(10):720-724.
kinds of plastrons and Cutictaeggplastron seemsto Mc PHERSON, j.E. & R.l. PACKAUSKAS. 1987. Life
beagood exampleof coalescenceof holes. history and laboratory rearing of Nepa apicu
As Hinton (1961) stated for the described ne lata (Heteroptera: Nepidae), with descriptions
pid species, aeropyles are absent in the centre of of inmature stages. Ann. Entomol. Soc. Am.
the horn crown and in the hydropyle. 80: 680-685.
The rnorphology of the egg of C. bonaerensis SITES, R.& B.j. NICHOLS. 1999. Eggarchitectureof
agrees with descriptions given for other Nepinae. Naucoridae (Heteroptera): Internal and exter
Itsegglaying had however, differsfrom thatofthe nal structure of the chorion and micropyle.
restofthe described Curictaspecies (Wiley, 1924; Proc. Entomol. Soc. Wash. 101(1): 1-25.
Keffer et al., 1994; McPherson & Packauskas, WICHARD,W.,W.ARENS&G. EISENBEIS.1995. Atlaszur
1987), it is also the only Nepinae which inserts Biologieder Wasserinsekten. G. FischerVerlag.
the eggsin leaves, abehaviourthatwas recorded WILEY, G. O. 1924.On the biologyofCuricie dra
only for Ranatrinae species (Cobben, 1968; Hin kei Hungerford (Heteroptera: Nepidae). Ent.
ton, 1961). Nevertheless Spirodela sp. could not News. 192: 324-331.
be the only substratum chosen in natural condi
tions. The position of the laid egg would fit the
description of endophytic Ranatra eggs (Hinton, Recibido: 9-XI-1999
1961). Aceptado: 30-1-2001
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