Table Of ContentGENERAL NOTE
JournaloftheLepidopterists'Society
58(2),2004,122-123
OVIPOSITION TIME TABLE OF INDIAN TASAR SILKMOTHANTHERAEA MYLITTA (SATURNIIDAE)
Additionalkeywords:oviposition,fecundity,nocturnal,copulation.
The Indian Tasar silk worm Antheraea mylitta callyanalyzedusingANOVA and£-test (Sokal & Rohlf
(Drury)isusuallyrearedundersemi-domesticatedcon- 1969).
ditions on its primaryhost plant Terminalia tomentosa All matingpairs starteddecouplingin the afternoon
W. &A. on alarge scale bya section ofatribal popula- followingcopulation (i.e. after 15 to 16hours ofcopu-
tion in tropical parts ofIndia. This insect (trivoltine at lation). The male moths were then removed from the
—
low altitude 300 m) is reared during rainy (July- breeding box. The oviposition rate peaked between
August), autumn (September-October) and winter 17.00 and 19.00 hours (Table 1). Then it decreased
(November-December) seasons forsilkharvest. From gradually andwas almost negligible after 20.00 hours
theharvestedcocoons some healthycocoons are sorted on all days. Probability values ofthe 't' test demon-
outforemergence, matingandoviposition ofmoths for strateastatisticallysignificantdifference (p < 0.01)be-
production of eggs. The harvested cocoons, which tween the number ofeggs laid in different hours dur-
yield raw silk, are the only means of income for the ing each day of oviposition (shown in the vertical
tribal rearers andsothis speciesis ofgreatcommercial column oftable 1) and between the number ofeggs
importance. Nevertheless there is no information laidindifferentdays duringdifferent hours ofoviposi-
available on oviposition time of A. mylitta although tion (shown in the horizontal column oftable 1) con-
similar studies are available for other sericigenous sidered in the study except between different days in
species such as Bombi/x mori Linn. (Tanaka 1964) and 06.00to 17.00hours. The datawere also analyzedas a
Samia ricini (Hutton) (Sarker 1980). This study pro- two-wayANOVA. There is significant (p < 0.01) varia-
vides atime-table ofoviposition ofA. mi/litta. tion among different hours of oviposition as well as
During each breeding season, at least 200 healthy amongdifferent clays of oviposition.
cocoonswere collected at random from the harvested The total duration ofoviposition was five days. The
cocoon lot of a trained rearer ofthe Association for highest (113.4 ± 5.8) number ofeggs was laid on first
Development ofSericulture, Baripada, in the district day of oviposition. On the following four days the
,
ofMayurbhanj ofOrissa State. All cocoons were pre- number ofeggs laid diminished drastically (Table 1).
servedin agrainagehouse foremergence. Afterabout The mean fecunditywas 194.7 ± 7.4. The rate ofegg
oneweekofpreservation ofJuly-August and Septem- layingsignificantlydifferedin differenthoursanddays.
ber-October harvested cocoons, and after six months Everydaythefirsthourofevening(17.00-18.00hours)
ofpreservation (due to diapause) ofwinter harvested showed significantly (p < 0.01) higher numberofeggs
cocoons, the moths emerged from cocoons during laid. Alowrateofovipositionwas observedatnight af-
midnight hours and started copulation. Twenty cou- ter 20.00H and during the clay before 17.00H. At all
pled healthypairs that emerged and copulated on the timesdieeggswarelaidinclusters. Mostovipositionin
same nightwere selected at random from the experi- a dayoccurred between 17.00 and 20.00H. This indi-
mentallot. Each matingpairwastransferredtoacard- cates howoviposition happens earlyinthe night.
boardbreedingbox (30 cm x 20 cm x 10 cm) for nat- The mated female moths ofA. mylitta, afterdecou-
ural decoupling and oviposition. The breeding boxes pling, commencedegglayingwiththeapproachoffirst
were numbered from 1 to 20 and were monitored hourofevening (17.00H) andcontinueduntil21.00H.
aroundtheclockfortheentire ovipositionperiod. The The peak hours ofeggs layingwere the earlyevening
rate (numberofeggs laid) and time ofovipositionwas hours (17.00to 19.00hours). Duringthe daytimevery
recorded for different hours and days. The observa- little oviposition was recorded. This indicates that
tions were repeated everyyear from 1994 to 1998 in darkness mayhave a stimulating effect on oviposition
all three breeding seasons. The mean value of20 ob- behavior. Similar trends were also observed in some
servationstaken duringeach ofthree seasons in ayear other species of moths. The female moths of Samia
wasconsideredas asingle replicate andthusthe mean ricini laid maximum eggs during the night, although
± standard deviation offive replicates for 5 years was some eggs were laid during day time (Sarker 1980).
taken fortabular presentation. The datawere statisti- The stimulating effect of darkness on egg laying of
Volume 58, Number 2 123
Table 1. TimetableofnumberofeggslaidduringdifferenthoursanddaysbyA. mylitta(Drury) (Mean± StandardDeviation;.
Day
Total
Hours 1st 2nd 3rd 4th 5th eggslaid 1*
— — — —
01.00to06.00 La\ingnot 2.5 ± 0.7 2.5±0.7
started — —
06.00to 17.00 Layingnot 1.2±0.1 1.4±0.2 2.6±0.8 NS
started
17.00to18.00 60.1 ±3.8 20.3±2.1 13.5± 2.3 9.6±2.1 6.3 ± 1.2 109.8±6.4 p<0.01
18.00to19.00 41.2 +3.1 7.8± 1.7 4.7± 1.3 2.3± 0.6 1.2—±0.4 57.2±4.7 p<0.01
19.00to20.00 6.7± 1.3 4.6± 1.1 2.8—±0.3 1.3—± 0.2 — 15.4±2.1 p<0.01
20.00to21.00 4.3 ± 1.2 l.S—±0.9 — — — 6.1 ± 1.6 p <—0.01
21.00to24.00 1.1 ±0.6 1.1 ±0.6
Total 113.4±5.8 38.2±4.1 22.4±2.6 13.2± 1.7 7,5± 1.2 194.7± 7.4
f p <0.01 p<0.01 p <0.01 p<0.01 p< 0.01 p <0.01
NS=NotSignificant.
t*=testofsignificancebetweenthenumberofeggslaidindifferentdaysduringdifferenthoursofoviposition.
Bombyxmori which oviposits at21.00H hasbeen con- The preparation ofthe present time table ofovipo-
firmed (Tanaka 1964). Plodia interpunctella Hubner sition of A. mylitta may be useful for handling the
showed maximum oviposition at dusk, and darkness Tasargrainage (eggproduction) operation in the most
was necessaryto stimulate egglayingwhereas lightin- convenientwayin Tasarfarmerswork.
hibitedit (Lum & Flaherty 1969, 1970). After mating,
commencement of oviposition occurred on the first Literature Cited
night in P. interpunctella (Richard & Thomson 1932). Chakravorty, S. & H. C. Das. 1983. Egglayingbehaviourofthe
ricemothCorcyracephalonica. Environ. Ecol. 1:169-174.
In the present investigation nocturnal oviposition be- Lum,P.T M.&B. R. Flaherty. 1969. Effectofmatingwithmales
havior ofAntheraea mylitta was observed. Similarbe- rearedincontinuouslightorinlight-darkcyclesonfecundityin
havior was reported in B. mori (Tanaka 1964). A. Plodiainterpunctella(Hubner).J. Stored.Prod. Res.5:89-94.
mylitta oviposited the majorityofeggs duringthe first lab.or19a7t0o.ryRebguylaltiigohntovainpdosidtiaornkbycoPnldoidtiiaonisn.terpuncEtceolnl.ainEntth.e
J.
four days after mating; oviposition continued for five 63:237-239.
days. In case the ofS. ricini, oviposition continues for Miller,TA.,W.J. Cooper&J.W. Highfill. 1983. Eggproduc-
2-3days (Sarker 1980). Callosamiapromethea (Drury) tion in female Callosamia promethea (Lepidoptera : Satumi-
idae)asafunctionofpupalsizeandadultlongevity.Ann. Ento-
oviposited most ofthe eggs during first three days af- mol. Soc.Am.76:668-670.
termating(Milleretal 1983).A. mylitta moths laidthe Richards, O. W. & W. S. Thomson. 1932. A contribution tothe
maximum numberofeggsonthe firstdayandtheleast satnuddyPloofditah,eGg.eNn.er(aLeEppihdeospttieara,,G.PNhy.ci(tiindcaleu)d,inwgitShtrnyotmeasxoDnvapra.r).-
numberon the lastday. asitesoftheirlarvae.Trans.Ent.Soc. Lond.80:169-250.
Since maximum number ofeggs ofA. mylitta were Sarkar,D.C. 1980.SericultureinIndia, 1stEd.CentralSilkBoard,
obtained during the evening, evening hours were SokalB,omRb.ayR,.5&1pF.p. Rohlf. 1969. Biometry—the principles and
found to be most favorable for oviposition. But night practices ofstaJt.istics in biological research, W.H. Freeman &
hours favored Corcyra cephalonica Stainton for maxi- Company,SanFrancisco,776pp.
mumoviposition (Chakravorty& Das 1983). Thegrad- Tanaka,Y. 1964.Sericologia,CentralSilkBoard, Bombav,277pp.
ualdeclineobservedinrate ofegglayingwithincrease
A. K. Dash, Department ofZoology, Dr. Jaclunath
ofage ofA. mylitta mothsisprobablydueto depletion
College, Rasalpur, Balasore- 756021, Orissa, India.
ofeggs inthe oviducttowardsthelastpartofadultlife.
Asimilartrendwas reported in S. ricini (Sarkar 1980) Receivedforpublication 22 itarch 2000; revisedandaccepted30
and C. cephalonica (Chakravorty& Das 1983). September2003
