Attachment Of A Microcaddisfly (Trichoptera : Hydroptilidae) Pupa To The Leg Of A Water Scorpion, Ranatra Buenoi (Heteroptera : Nepidae)

3 Pages·2002·0.96 MB·English

by  D E Bowles

Vol. 113, No. 4, September&October, 2002 267
ATTACHMENT OF A MICROCADDISFLY
(TRICHOPTERA: HYDROPTILIDAE) PUPA
TO THE LEG OF A WATER SCORPION,
RANATRA ££/£AW(HETEROPTERA: NEPIDAE)
1
DavidE. Bowles^,Jason L. Loekliiw
ABSTRACT:Amicrocaddisflypupa(Trichoptera: Oxyethira)wasfoundattachedtothelegofa
predatory water scorpion (Hemiptera: Ranatra). Other reported instances ofOxyethira pupae
attachingtoaquaticinsectsindicatethisbehaviormaybecommonforthisgenus.Thebehavioral
mechanismsthatpermittedthemicrocaddisflytoattachitselftothewaterscoipionwithoutbeing
attackedareunknown.
The caddisfly genus Oxyethira, (Trichoptera: Hydroptilidae), is distrib-
utedworldwideandapproximately40species areknownfromNorthAmerica
(Wiggins 1996). MoultonandStewart(1997) reported 17 species ofOxyethira
occurinTexas.Thewaterscorpion,RanatrabuenoiHungerford(Heteroptera:
Nepidae),iswidelydistributedinthesoutheasternU.S.,includingTexas (Sites
and Polhemus 1994). Recently, we collected aR. buenoinymph to which an
early pupa ofOxyethira was firmly attached on the left metathoracic femur
(Fig. 1). Both ends ofthe formerlarval case had been attached to the nepid's
leg, the ends were sealed, andapolysis ofthe larval cuticlewas evident. How-
ever, ecdysis had not yet occurred and the early, pharate pupa could be dis-
mm
cernedthroughtheold larvalcuticle. Thelengthofthepupawas2.8 (case
3.2mm) and theR. buenoiwas16.5 mm in length (headto apex ofrespiratory
siphons). The specimens were hand collected on 14 June 1999 in a stream
W
pool ofDry Creek, Montgomery County, Texas (N 30° 14' 19.8" 95° 19'
21.6"). In addition, 17 fifth instar Oxyethira larvae and two adult R. buenoi
mm
were collected with a benthic sampling net (600 mesh) at the same loca-
tion and sampling date. Larvae formost species ofOxyethira have not been
associatedwith adultstages sowewereunable to determinethe specific iden-
tity ofthese specimens.
WhiteandFox(1979) foundseveralpupalcasesofOxyethiraaztecaMosely
that were fastened to a dragonfly nymph, Macromia georgiana (Sel.), col-
lected from a South Carolina stream. Our finding of Oxyethira pupating on
anotheraquatic insect suggests that such behaviormay be fairly common for
this genus. Oxyethira azteca also commonly occurs throughout most ofeast-
ernTexas,andthespecimenswecollectedcouldrepresentthisspecies.Whether
this instance represents directed phoresy or is a more random action is un-
1 ReceivedJanuary28,2002. AcceptedFebruary23,2002.
2TexasParksandWildlifeDepartment,P.O. Box 1685,San Marcos,Texas 78667.
3 DepartmentofBiology, SouthwestTexas StateUniversity,SanMarcos,Texas 78666.
ENT. NEWS 113(4): 267-269,September&October, 2002
268 ENTOMOLOGICALNEWS
'^Ksi"i''ft****
Figure 1. A waterscoipion,Randtra buenoi Hungerford, witha microcaddisfly (Oxyethria sp.)
attachedtothemetathoracic femur.
known. Thepossibility exists that the caddisfly mayhavemistaken the leg of
the water scorpion to be a twig or similar inanimate object. White and Fox
(1979)suggestedthattheattachmentofOxyethirapupaetothedragonflynymph
theycollectedwas relatedto thepaucityofnaturalhabitatandsuitableattach-
ment sites in the channelized stream they studied. This was not the circum-
stance for the present study location because the flowing stream contained
ample woody debris and riparian vegetation.
Althoughtheproboscisofthewaterscoipionwecollectedis incloseprox-
imity to themicrocaddisfly, thebodyofthe latterwas fully intactandhadnot
been pierced. The closeness ofthe nepid's proboscis to apotential food item
suggests thatmicrocaddisflies mightnotplay a role in the diet ofthesepreda-
tory insects orthat itwas unable orunwilling to attackthe larva as itattached
itselfprior to pupation. Also, the nepid simply could have been unaware that
the caddisfly was present.
ACKNOWLEDGMENTS
WethankRobertW. Sites,SharonKnightJasper,andanonymousreviewers forcomment-
ingonanearlierdraftofthispaper.KarimAzizandGaryCaldwellassistedwithpreparationof
thephotograph.
Vol. 113, No. 4, September& October, 2002 269
LITERATURE CITED
Moulton, S. R., Ill, and K. W. Stewart. 1997. A preliminary checklist ofTexas caddisflies
(Trichoptera). Pp.349-353,InR.W. HolzenthalandO.S.Flint,Jr. [editors], Proceedingsof
the 8th International SymposiumonTrichoptera, 1995, Ohio Biol. Surv., Columbus.
Sites, R. W.,andJ. T. Polhemus. 1994. Nepidae(Hemiptera)oftheUnitedStatesandCanada.
Ann. Entomol. Soc. Am. 87:27-42.
White,T. R., and R. C. Fox. 1979. Chironomid (Diptera) larvae and hydroptilid (Trichoptera)
pupae attachedto a macromiid nymph (Anisoptera). Notulae Odonatologicae 1:76-77.
Wiggins, G. B. 1996. Larvae ofthe North American caddisfly genera (Trichoptera), 2nd ed.
Univ. ofToronto Press,Toronto.