Table Of ContentBIOECOLOGICALSTUDIES ONTHE BURROWING MAYFLYEPHEMERA
(AETHEPHEMERA)NADINAE MCCAFFERTYAND EDMUNDS 1973
(EPHEMEROPTERA EPHEMERIDAE) IN KURANGANI STREAM,
:
WESTERN GHATS 1
C. Balasubramantan, K. Venkataramanand K.G. Sivaramakrishnan2
(With threetext-figures)
ThelifecyclepatternofEphemeranadinaeinKuranganistreamwasinterpretedfromthedevelopmental
stagefrequencyhistograms. Itisbasicallymultivoltinewithasynchronous,overlappinggenerationsorcohorts
withcontinuousemergence.FoodhabitsofE.nadinaewereinvestigated.Detritusformsthemajorfood.Meagre
amountofmineralsandplanttissueswerenotedinthegut,whichmighthavebeenconsumedwithnormalfood
incidentally. Theemerging behaviourofsubimagos was also studied. Theyemergesoon aftersunsetatabout
1830hrs throughoutthe year. Synchronous emergenceofboth sexes was recorded,withmalesoutnumbering
females.Subimagosemergeonthewatersurface.Longevityoftheadultsrangesfrom24to48hours.Theaverage
number ofeggs/mm of body length in E. nadinaewas 240 (r value = 0.9). The fecundity ofE. nadinae is
comparedwithco-existingspeciesofloticmayflies.
Introduction is exposed to the effects of the south-west mon-
soon, the north-east monsoon and summer. For
Knowledge of ecology and life histories of ecological studies, February through May are
allimportantgroupsofaquaticinsectsisessential treated as summer, June through September as
inunderstandingthebiologicalstructureoffresh- south-westmonsoonperiod and Octoberthrough
water streams and lakes. Ecological studies on January as north-east monsoonperiod.
lotic systems in India with emphasis on
MaterialandMethods
Ephemeroptera are very few (Gupta 1980,
Sivaramakrishnan and Job 1981, Venkataraman The study was conducted from February
1984, Kumar 1987). Though there are a number 1988 to January 1989. Three kick samples of
ofstudies onlifecycles ofephemerids inhabiting ephemeridswerecollected fromsandyregions of
temperateregions(Kurodaetal. 1984,Schloessor Kurangani stream. The sandy habitat was dis-
andHiltunen1984),thereis apaucityofinforma- turbed preferably by five horizontal and fivever-
tion on the life cycle patterns of tropical tical vigorous kicks strictly restricted to one
ephemerids including peninsular Indian forms. square metre area. Nymphs thus collected were
Thisstudyexaminesthelifecyclepattern,feeding preservedin70%alcoholandweresortedaccord-
propensities, emergence and fecundity of ingto age-class. The plan ofClifford (1969)was
Ephemeranadinae aburrowingmayfly,inathird followed and in the classification of stages,
,
order stream in Kurangani village of the Car- nymphsweregroupedinto fourarbitrarilychosen
damomhills ofWestern Ghats. developmental stages on the basis ofappearance
and the development ofmesothoracicwingpads.
StudyArea
Stage I nymphs lacked wing pads; stage II
Kurangani (11° N, 77°50'E), the study area, nymphshadwingpadsthatwereshorterinlength
is situated 116 kmwest ofMadurai, TamilNadu. than the distance separating the two wing pads;
It lies onthe north-easternside ofthe Cardamom the wing pad length of stage III nymphs was
m
hillsatanaltitudeof650 abovem.s.l. Thisarea greaterthanthedistance separatingthe forewing
1AcceptedDecember1989. pads. Stage IVnymphs had darkened wingpads.
2CentreforResearchinAquaticEntomology,Dept, ofZool- Each stage represents several instars, with
ogy,MaduraCollege,Madurai,TamilNadu625Oil. the exception ofstage IV, which is the last nym-
THE BURROWING MAYFLY EPHEMERA (AETHEPHEMERA) NADINAE 73
diately in 70% alcohol, and later sorted in the
laboratory. Five to ten nymphs of assorted
varieties in every month were used for gut
analysis. Stage IVnymphs were notused forgut
analysisastheywerealmostreadyto emergeand
hardly ingestedany food atthetime. The foregut
portion up to second abdominal segment was
dissected and the contents were rolled out and
teased. The suspension ofthe food material was
transferred to Sedgewick rafter. The suspension
was allowed to stand for some time to allow
sediments to settle. The percentage composition
was determined by counting the cells of
Sedgewick rafter of different food materials,
usinga compound microscope.
Subimaginal emergence was monitored
duringsouth-west monsoon, north-eastmonsoon
andsummerperiods. Monthly tripswere madeto
Kuranganiandlighttrappingwas donewitha125
wattmercuryvapourlamppoweredbyaportable
generator. Light was switched on from 1800 to
2030 hrs and from 0500 to 0630 hrs. Subimagos
were collected in subimaginal box cages (Ed-
munds et al. 1976). Longevity (emergence to
imago-deathinterval)was determinedinthesub-
imaginal box cages at room temperature (28 ±
2°C) inthe laboratory.
Fecundity is the total number of eggs
produced by the female during her life span,
Fig. 1.pH,currentvelocityandairandwatertemperature in
regardless ofthe fate oftheeggs. Formeaningful
Kurangani stream,atmonthlyintervals fromFebruary 1988
toJanuary1989. comparisonbetweenspecies, the relationshipbe-
tween egg production of E. nadinae and body
phal instar, the tanwingpads indicating impend- length was analysed. The eggs from the ab-
ing emergence. Nymphs were sexed only after dominal and thoracic body cavities oflast instar
stage IIonthe basis ofgenitalia. (with darkened wingpad) nymphs ofE. nadinae
Physico-chemicalparameterswererecorded were removed to Sedgewick rafter and counted.
during collection time. During each visit atmos- The relationship between fecundity and body
pheric and water temperatures were recorded. lengthwas statistically analysed.
Watervelocitywasdeterminedbythecorkfloata-
tionmethod.pHofwaterwas notedwiththehelp ResultsandDiscussion
of BDH broad and narrow range pH indicator Life cycle pattern: The physico-chemical
papers. parameters like temperature, pH and water
The method employed forfood analysis is a velocity ofKurangani streamare shown inFig.
combinationofthemethodsfollowedbyMinshall 1. pH of the stream tended to decrease during
(1967) and Gupta and Michael (1981). Nymphs southwestmonsoonandtoincreaseduringsum-
were collected at monthly intervals, fixed imme- mer. The atmospheric and water temperatures
74 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol.89
Fig. 2. MonthlychangesinthedistributionofE. nadinaeadultsandnymphs.
A-indicatesmonthswhenemergingmayflieswerefound.
showed large fluctuations during different and Ambuhl 1964, Edington 1968), substratum
seasons. (Rabeni and Minshall 1977, Shaw and Minshall
Several factors are known to influence the 1980)and food(Egglishaw 1964, 1969;Williams
distribution ofaquatic insects. But important en- and Hynes 1973).
vironmental factors likely to affect animal num- ThelifecyclepatternofE. nadinaeinKuran-
berwithinavery smallsegmentofthestreamare gani stream is interpreted from developmental
water velocity (Scott 1958, Ambuhl 1959, Jaag stagefrequencyhistograms(Fig.2).Itisbasically
THE BURROWING-MAYFLY EPHEMERA (AETHEPHEMERA) NADINAE 75
multivoltine with asynchronous, overlapping good for explaining the food habits of
generationorcohortswithcontinuousemergence. Ephemeroptera or even other groups of aquatic
Acohort is a group ofindividuals thatwerebom insects (Cummins 1973). Gut content analysis of
at the same time, orinpractice bom overa short E. nadinaerevealedameagreamountofminerals
period oftime. Early instars ofE. nadinae occur and plant tissues which might have been con-
around July and this cohort continues up to sumed with normal food incidentally.
November. Besides, the presence of two other Emergence: Emergence is probably a
cohorts which occur during January and April is ‘safetyin numbers’strategy evolvedtomaximise
suggested. survival from predation at one ofthe vulnerable
The life cycle patterns of ephemerids from periods in the life cycle of mayflies (Friesion et
temperate regions show agreement as well as al. 1980).Inthepresentinvestigation,E. nadinae
deviationfromtheobservedpattern.Forinstance, emergedaftersunset(around 1830hrsthroughout
the life cycles of E. japonica and E. orientalis the year). Similar dusk emergence was observed
also havetwo orthree cohorts ina year, suggest- by Takemon (1985) in£. japonica. He observed
ing multivoltine pattern, whereas E. strigata is E. strigata to emerge in the afternoon.
evidently univoltine in having only one cohort Synchronous emergence of both sexes of E.
(Kurodaet al. 1984).ThelifecycleofHexagenia nadinaewas recorded, with males outnumbering
limbataofSt.Marysriver,Michigan,iscomposed females. As against the male-biased emergence,
of two non-synchronous emerging cohorts each female-biased emergence has been recorded in
with a two-year life span (Schloessor and Hil- some tropical mayflies (Poyyamoli 1984,
tunen 1984). Venkataraman 1984).
Feeding propensities: Mayfly nymphs do EdmundsandEdmunds(1980)pointoutthat
not play the same role in the trophic structure of apparentlymanyoftheactivitypatternsandadap-
the communities inwhichthey occur. In view of tations of mayfly subimagos and imagos have
this,knowledgeoftheirfeedinghabitsisdesirable formed in response to selection pressure from
(Brown 1961). Studies on food habits oftropical predators. Mayfly subimagos, being slow and
and subtropical mayflies are very few clumsy fliers, are highly vulnerable to predation.
(Sivaramakrishnan 1980, Gupta and Michael Nocturnal emergence observed in the
1981, Venkataraman 1984). In the present inves- present study may be attributed to the following
tigation, detritus formed the major food. Studies reasons as suggested by Poyyamoli (1984) and
by Venkataraman (1984) on nymphs of hep- Takemon(1985):
tageniidsofPalanihillstreamsrevealthattheyare (1)Thecuticleofnewlyemergedadultswill
algivores, whereas the same species and some be thin. As a result, they have to emerge during
lcptophlebiids of Courtallam hill streams are cooler hours, when evaporation is at its lowest.
detritivores (Sivaramakrishnan 1980). Night time intropics is ideal.
The absence of canopy formation by forest (2) Nocturnal emergencehelpsthese insects
trees on the banks of Kumbakkarai stream in to escapefromvisual predators.
Palanihills favoursalgalgrowthinrockybottom. The emerging behaviour of E. nadinae of
The limited vegetation near the bank may be Kurangani stream was found to be of the water
correlatedwithminimalamountofallochthonous surface type and the behaviour is similar to E.
detritus. TheconditioninCourtallamhillstreams strigata of Japan (Takemon 1985). However,
is different, with poor access to direct sunlight nymphs ofE.japonica afterreaching the surface
overthe streamdue to canopy formation. Kuran- swam directly ahead along the surface with
ganistreamisinthisrespectsimilartoCourtallam forelegs stretched forward until they came into
streams.Thestatementthatlocalconditionsbeget contactwithapartially submerged objectsuchas
local results (Muttowski and Smith 1929) holds a rock or plant. The longevity of adults (emer-
76 JOURNAL, BOMBAY NATURAL HIST SOCIETY, Vol.89
Minshall (1967) found that beyond a size range
(10.5 mm) the number of eggs decreased with
increasing size of the individual. This apparent
decline in egg numberwith increasing body size
(upto31mm)hasnotbeenobservedinthepresent
study.
The average number of eggs/mm of body
length inE. nadinae is 240 (r value = 0.9). The
data of Clifford and Boerger (1974) for Bigory
river mayflies of Canada, Hunt (1951) and Britt
(1962) for Ephemerids and of Minshall (1967)
andVenkataraman(1984)forHeptageniidswould
indicate 137-222 eggs/mm, 300-350 eggs/mm
and 100-200eggs/mmrespectively.
Among the mayfly species, the burrowing
Ephemeridae are the longest. But the rate ofegg
production is very high (1843 eggs/mm) only in
Heptageniidae(SridharandVenkataraman1989).
TheEphemeridaeareburrowingandsandyforms,
whereas heptageniids are rheophilic and are
restricted to torrential areas of rock-bottomed
streams. This difference in ecological niche
probablynecessitatestheproductionofmoreeggs
to compensate forthe loss ofeggs being washed
away (SridharandVenkataraman 1989).
Acknowledgements
Fig.3.Relationshipbetweenbodylengthandnumberofeggs
inE.nadinae. We are indebted to Dr T. Chandraguru,
gence to imago-death interval) of E. nadinae Department of Zoology, V.H.N.S.N. College,
ranged from 24to 48 hours. Virudhunagar for many valuable suggestions.
Fecundity: The correlation between the We thank S. Sridhar for assistance in field
number ofeggs produced byE. nadinae and the trips. This work was supported by a grant
body lengthispresentedinFig. 3.Itconfirmsthe fromthe University Grants Commission,New
general view that fecundity increases with in- Delhi, which is gratefully acknowledged.
creasing body length of the nymphs. However,
Refe ENCES
Ambuhl, H. (1959): Die Bedeutung der stromung als 597.
okologischerFaktor.Schweiz.Z.Hydrol.21: 133-264. Clifford, H.F. & Boerger (1974): Fecundity of Mayflies
Britt, N.W. (1962): Biology of two species of Lake Erie (Ephemeroptera) with reference to mayflies of a
mayflies, Ephoron album (Say) and Ephemera brown-waterstreamofAlberta,Canada.Can.Entomol.
simulansWalker.Bull OhioBiol.Surv. No. 1.70pp. 106: 1111-1119.
Brown,D.S. (1961):Thefoodoflarvaeof Cloeondipterum Cummins, K.W. (1973): Trophicrelationsofaquaticinsects.
L. and Baetis rhodani Pictet (Insecta : Ephemerop- Ann.Rev.Ent.18: 183-206.
tera).J.Arum.Ecol. 30:55-75. Edington, J.M. (1968): Habitat preference in net-spinning
Clifford, H.F. (1969): Limnological features ofa northern Caddislarvaewithspecialreferencetotheinfluenceof
brown-waterstream, withspecial referenceto thelife watervelocity.J.Anim.Ecol.34:675-692.
historiesoftheaquaticinsects.Am.Mid.nat.82:578-
: :
THE BURROWINGMAYFLY EPHEMERA (AETHEPIIEMERA) NADINAE 77
Edmunds, G.F., Jr. & Edmunds., C.H. (1980): Predation, Am.Mid.nat. 78:369-387.
climate, emergence and matings of mayflies. Adv. Muttowski, R.A & Smith, G.M. (1929): The food oftrout
Ephemeroptera Biol. Proc. 3rdInL Conf. Ephemerop- stream insects in Yellowstone National Park. Ann.
tera,Winnipeg,Canada. Roosevelt. Wildl.2:241-263.
Edmunds, G.F., Jr., Jensen, S.L. & Berner, L. (1976): Poyyamou,G.(1984):Ecophysiologicalstudiesonenergetics
Mayflies of North and Central America. Univ. Min- ofchosen organisms (Studies on diel emergence pat-
nesotaPr.,St.Paul. terns of some tropical aquatic insects). Ph.D. thesis,
Eggushaw, II.J. (1964): The distributional relationship be- School of Biological Sciences, Madurai Kamaraj
tweenthebottomfaunaandplantdetritusinstreams.J. University.
Anint.Ecol33: 463-476. Rabeni, C.F. & Minshall, G.W. (1977): Factors affecting
Eggushaw,H.J.(1969):Thedistributionofinvertebratesina microdistributionofstreambenthicinsects.Oikos29:
high mountain brook in the Colorado Rocky Moun- 33-43.
tains. Univ. Colo.Stud.Ser.Biol.31 : 1-114. Schloessor,D.W. & Hiltunen,J.K. (1984): Lifecycleofa
Frieson, M.K., Flannagan, J.F. & Laufersweiler, P.M. mayflyHexagenialimbata in theSt. Mary’s riverbe-
(1980): Diel emergence patterns of some mayflies tweenLakes SuperiorandHuron.J. GreatLakesRes.
(Ephemeroptera) of the Roseau river"(Manitoba, 10(4):435-439.
Canada).Adv.EphemeropteraBiol.proc.3rdInt.Conf. Scott,D.(1958):EcologicalstudiesontheTrichopteraofthe
Ephemeroptera,Winnipeg,Canada. RiverDean,Cheshire.Arch.Hydrobiol.54 340-392.
Gupta, A. (1980): On the taxonomy and biology of Shaw, D.W.& Minshall, G.W. (1980): Colonizationofan
Ephemeroptera (Mayflies) ofMeghalaya State,India. introduced substrate by stream macro-invertebrates.
Ph.D.thesis,North-EasternHillUniversity,Shillong. Oikos34:259-271.
Gupta,A &Michael,R.G. (1981): Populationecologyand Sivaramakrishnan,K.G. (1980): Taxonomyandecologyof
feeding propensities of two co-existing species of Leptophlebiidae (Ephemeroptera) in Southern Penin-
Baetidae(Insecta :Ephemeroptera).Proc.Symp.Ecol. sularIndia.Ph.D.thesis,SchoolofBiologicalSciences,
Anint.Popul.Zool.Surv.India.2:95-104. MaduraiKamaraj University.
Hunt, B.P. (1951): Reproduction of the burrowing mayfly, Sivaramakrishnan, K.G. & Job, S.V. (1981): Studies on
Hexagenia limbata (Serville), in Michigan. Fla. En- mayflies population in Courtallam streams. Proc.
tomol.34 59-70. Symp.Ecol.Anim.Popul.Zoo.Surv.India2:105-116.
Jaag, O. &Ambuhl,H. (1964): Theeffectofthecurrenton Sridhar, S. & Venkataraman, K. (1989): Fecundity of
the composition of biocenoses in flowing water mayflies ofWestern Ghats ofPeninsular India. Curr.
streams. In : Int. Conf. Wat. Pollut. Res. Lond., Sci. 58(20): 1159-1160.
PergmonPress,Oxford,pp.31-49. Takemon, Y. (1985): Emerging behaviour of Ephemera
Kumar, K. (1987): Observations on seasonal variations of strigata and E. japonica (Ephemeroptera :
benthic organisms in two trout streams of Kashmir. Ephemeridae).Physical.Ecol.Japan22: 17-36.
Proc.IndianNatu.Acad.B53(3):227-234. Venkataraman,K.(1984):Taxonomicalandeco-physiologi-
Kuroda, T., Fujimoto,T. & Watanabe,N.C. (1984): Lon- cal studies of mayflies (Ephemeroptera : Ilep-
gitudinaldistributionandlifecycleofthethreespecies tagenidae).Ph.D.thesis,SchoolofBiologicalSciences,
ofEphemeraintheKazuradaniriver,KagawaPrefec- MaduraiKamaraj University.
ture.KagawaSeibutsu02: 15-21. Williams, N.E. & Hynes, H.B.N. (1973): Microdistribution
Minshall,J.D. (1967): LifehistoryandecologyofEperous and feeding of the net-spinning Caddisflies
pleuralis (Banks) (Ephemeroptera: Heptageniidae). (Trichopera)ofCanadianstream.Oikos24:73-84
6
