Laboratory Studies on Trichogrammatoidea bactrae Nagaraja as an Egg Parasitoid of Diamondback Moth Piute/la xylostella (Linnaeus)
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Date
1999
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UHF,NAUNI
Abstract
Laboratory studies on Trichogrammatoidea bactrae Nagaraja as an egg parasitoid of diamondback
moth, Piute/la xy/ostel/a (L.), were caaied out at 26±1°C and 50-80. per cent relati\le humidity duril:tg
1998·99 at Nauni, Solan with o't>jectives of detennining pruasitl.7.atlon potential. emergence, sex ratio.
fecunditiy, longevity and mortality pattern on P. xylostel/a and its laboratory host Corcyra cephalonica
(Stainton) along with suitable storage temperatute for hotding parasitized eggs of C. cephalonfca, lo its
laboratory maintained culture, upto 2 adult parasitoids per pardSitized C cephalonica egg emerged with
almost equal chan.ces of getting I or 2 parasitoids. Females of 1: baatrae parasitized on an average 6.4
eggs of C ieph.alonica and 4.6 eggs of P. rylostella during its survival of 2.3 and l.7 days. respectively.
The fecundity was 9.1 on eggs of C. cepholonico and 6.3 on eggs of P. xylostella but average adult
emcrgence'from these parasitized eggs was 6.2 and 3.9. ·(0.97 and 0.85 per egg). respectively. The mean
nwnbc.r. of eggs with exit bole was 4.3 and 2.9 for C cephalonita and /'. zylostella. Amongst eggs without
adult emergence hole, dead larvae, pupae and. adults were prese.nt; their percentage was 9.2. 60.4 and 30.4
in C. c~phalonica eggs and 8.7, 57.5 and 33.8 in'P. rylo.vtella eggs. respe.c1lvel~·. Tiius, maximum mor1ality
occurred In pup:il stage on bOlh l.hese hostS. The female : m11 lc sc." r;il.io wns female biased (2. Is: I n11d
L82: l) and perce01age of females was 68.6 and 64.6, respcc1lvcly for these two hosts.
For moderate emergence of the parasitoid from eggs stored on cards at low temperature. it was
found that the storage after 3 to 7 days of parasitiz,ation for 5 days at to0c resulted in above SO per cen.t
adult emergence and eggs could not be stored for more than 7 days. However, at I s0c these could be
stored upto 18 days bul with low emergence (H.2%). The effective trealln1'fll proved to be storage of
r.richo-<:ards ~ ts0c for s days after S days of parasiti23tion (72.3% eggs witl1 emergence hole}, at ts0c
for IO days after 5 days of parasiUzation (69.8%), and at 1s0c for 5 clays after 3 clays of parasiuzation
(69.4%). [n view of this, storage combination at 1 s0c for 10 days after 5 day'S of parasilizalion will be a
right choice and storage can be made uplo 15 days at tl1ese conditions bul at the cost of reduced adult
emergence (40%).
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