| Summary: | Helicoverpa armigera (Hubner) (Noctuidae: Lepidoptera),
commonly known as legume pod borer, is a major insect
pest of legume crops in the semi-arid tropics. A baculovirus
of type nucleopolyhedrovirus (NPV) was isolated from this
insect during natural epizootics at ICRISAT. Patancheru
(Andhra Pradesh, India). Electron microscopic studies
showed that the occlusion bodies (OBs) are in polyhedral
shape and approximately 2 pin in diameter containing
multiple nucelocapsids per envelope and purified virus
particles revealed bacilliform tocylindrical shaped structures
of size of 282 x 49 nm. In bioassays the virus on 2nd and
3'* instar H. arinligera larvae had LCs0 values on 71h day
are 2.30 x lo4 and 1.5 x lo5 POBs/ml and LTsO values at
virus con cent ratio^^ of 1.8 x 10' POBsIml are 118.80 and
133.92 hr respectively. The virus yield was high in the fieldcollected
larvae (5.60 x lo9 POBs/larva and/or 14.01 x loy
POBs/ml) than laboratory reared larvae (5.02 x109 POBs
/larva and/or 12.42~lo 9P OBS/~Ib)u,t no variation in their
virulence (LCs0 values on 7t'1 day: 1.79 x 105 and 1.11 x
lo5 POBs/ml). Using a degenerate oligonucleotide primer
set polyhedrin gene of the virus was amplified by PCR. This
resulted in a 744 bp product w hich was cloned and sequenced.
The nucleotide gene sequence had a high ho~nology with
several NPVs, specifically with NPV from Mutnestra
brassicue (97%), Marnestra cor$gl~rura (97%) and Leucariirl
seperata (95%) (Noctuidae: Lepidoptera) and these three
viruses shared a unique restriction site for Xlzo-I enzyme
at nucleotide position 130 (M. brossicae and M. cor?fi,purata)
and at 670 (L. seperata). The phylogenetic analysis showed
that the virus belongs to Group-I1 NPVs and the virus was
named as Helicoverpa arniigera N~~cleopolyhedorivrus
(NPV), Patancheru strain. This is the 81h report worldwide
and first report from the Indian subcontinent to be
described the complete polyhedrin gene of a NPV isolated
from H. armigera. Field efficacy studies of this virus (250
LE/ha) againstH. arrnigem on chickpeacrop wascomparable
with fields sprayed with n synthetic insecticide (endosulfan
at 0.07%) confirming its i~sefi~lnefsosr controlling legume
pod borer.
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