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Journal of Entomology and Zoology Studies 2020; 8(4): 341-343
E-ISSN: 2320-7078
P-ISSN: 2349-6800
www.entomoljournal.com
JEZS 2020; 8(4): 341-343
© 2020 JEZS
Received: 08-05-2020
Accepted: 10-06-2020
JP Baruah
Department of studies in
Sericulture Science, University of
Mysore Manasagangothri,
Mysore, Karnataka, India
Chinmoyee Kalita
Department of studies in
Sericulture Science, University of
Mysore Manasagangothri,
Mysore, Karnataka, India
Corresponding Author:
JP Baruah
Department of studies in
Sericulture Science, University of
Mysore Manasagangothri,
Mysore, Karnataka, India
Integrated pest management of uzi fly (Exorista
sorbillans) in Muga silkworm Antheraea
assamensis Helfer (Lepidoptera: saturniidae): A
review
JP Baruah and Chinmoyee Kalita
Abstract
Muga silkworm rearing being an outdoor crop due to insect pests is a major problem encountered by the
muga rearers. It is mostly high in the pre-seed (Aherua and Jarua) and seed crop (Chotua and Bhodia)
compared to the commercial crops. A preliminary study from 2010 to 2011 revealed 12 (Twelve) insect
pests belonging to family Tachinidae, Vespidae, Ichneumonidae, Braconidae, Formicidae, Pentatomidae,
and Mantidae infesting the silkworm. Among these families, the Tachinidae family infest the silkworm
more and the uzi fly belongs to the Tachinidae family. Exorista sorbillans, Widemann, otherwise called
the uzi fly is a serious pest of muga silkworm and is a problem for silkworm rearing. The incidence of
this fly is very high in tropical Sericultural regions. Uzi fly damages 25% crop loss in the 4th to 5th instar
and 20% at harvesting stage of cocoons during Chotua crop (March-April). Applications of insecticides
for control of the uzi fly is not advocated in muga rearing as it is lethal to the muga silkworm itself. This
review mainly focuses on Integrated Pest Management of Uzi fly, (Exorista sorbillans Wideman) in
muga silkworm (Antheraea assamensis Helfer). This review also covers the life cycle of the uzi fly and
its nature of the damage.
Keywords: Antheraea assamensis, muga silkworm, uzi fly, integrated pests management, lepidoptera
Introduction
Muga silkworm, Antheraeaassamensis Helfer (Lepidoptera: Saturniidae) is semi-domesticated,
polyphagous, multivoltine, and endemic to Assam, yields golden yellow silk. The Tibeto-
Burmese and Indo-Mongoloid tribes successfully domesticated muga silkworm similar to that
of farm animals possibly for getting proteinous dishes from the larvae and pupa initially and at
the advent of civilization they exploited golden yellow muga silk for preparation of fabric for
their domestic us [1]. Gradually it became an indispensable traditional symbol in the Assamese
way of life. Muga silkworm feeds primarily on ‘som’, Persea bombycina Kost and ‘Soalu',
Litsea polyantha Juss and many other secondary food plants. The muga silkworm is reared in
5-6 seasons in the year. The Jethua (April-May), & Kotia (October-November) rearings are
commercial crops, Chotua (February-March) & Bhodia (August-September) as seed and Jarua
(December-January) & Aherua (June-July) as pre-seed crops [1].
Muga Silkworm is attacked by several parasitoids (Exorista sorbillans; Apanteles sp.) and
predators (ants, wasps, birds etc). Among these E. Sorbillans is one of the serious larval
endoparasitoids of silkworm (Antherea assamensis). It causes extensive damage to the
sericulture industry. During Jarua (December-January) and Chotua (February-March) crop
seasons and reported 20-90% loss in winter & post winter (December-March) [4] and 50-70%
cocoon rejection during February-March [3]. The mature maggots come out of the larvae/pupae
and undergo pupation in the rearing field or grainage hall. The uzi infested muga silkworm
dies during the larval or pupal stage. This parasitoid was also reported on 95 species of insects
belonging to 20 families of Lepidoptera and one family of Hymenoptera worldwide in the
absence of silkworm [2].
Thangavelu and Sahu [6] reported that the maggots of the Uzi fly exhibited considerable
variation in their body size and the maggots developed within B. mori larvae were generally
smaller in size while those developed within A. assamensis larvae were comparatively larger.
They also pointed out that the considerably large sized muga silkworm might have provided a
more suitable niche to the uzi fly maggot than the smaller silkworm.
Journal of Entomology and Zoology Studies http://www.entomoljournal.com
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As per the recent survey results indicates that the maximum
infestation of uzi fly was recorded in 5th instar larvae (43.0%)
and harvesting of cocoons (35.0%) during Chotua crop
(March-April 2010) followed by Jarua crop, Dec. 2009-Jan.
2010 (19.0%) infestation at larval stage & 27.50% at
harvesting stage of cocoons) reported in upper Assam [5]. To
reduce the infestation level of uzifly, the following intregated
management practices to be recommended.
The Life cycle of uzi fly
Uzi fly completes their life cycles in four stages, viz egg,
maggot pupa, and adult.
Egg: Eggs are creamy white in colour. The egg measures
0.45-0.56 mm in length and 0.25-0.30 mm in width. They are
oblong in shape and hatch in about 2-5 days after oviposition.
Once hatched, the maggot penetrates into the body of the
muga silkworm [12].
Maggot: This is the second stage of uzi fly. Maggot has three
instars. The young maggot hatches out of the eggshell through
the operculum which generally faces the silkworm body.
After hatching from the eggs, the maggots of the fly penetrate
into the larval body and feed on the tissues of the worms [2]. In
the 1st two instars, they develop just below the skin of the host
body and in the final instar, they leave this site and move into
the body cavity. Maggots are yellowish-white in colour and
measure 1.3-1.6 cm in length. Maggots have eleven body
segments. They feed on various tissues of the silkworm body.
The mature maggots escape from the host body by piercing
the integument by its thoracic hooks.
Pupa: Pupae are oblong in shape and round posteriorly.
Pupae are light reddish-brown to dark reddish-brown in
colour. The body has 11 segments and measuring 0.9 to 1.2
cm in length and 0.4 to 0.6 cm in lateral width. Adults emerge
in about 10-12 days [6].
Adult: Adults are blackish-grey in colour. Male is longer than
the female. The head is triangular in shape. On the dorsal side
of the thorax, there are four longitudinal black bands. The
abdomen is conical. In the abdominal segments, the first one
is black and the rest grayish-yellow. The life span of adult
flies varies with sex and season [5]. Males survive for about
10-18 days. Females live 2-3 days longer than males. The
survival period is less during the summer months.
Integrated management practices to be followed for
Exorista sorbillans
The extensive damage to silkworm crops due to uzi menace in
sericulture created an appalling situation and shaken the very
root of sericulture in India. Thus, the threat of notorious fly
pests becomes a serious concern especially because no
preventive/control measures were known to
check completely the uzi infestation. Control of Indian Uzi fly
and non mulberry uzi fly has engaged the attention of several
workers in the past and various approaches such as preventive
measures using mosquito nets, trapping of female uzi fly have
been suggested.
1) Mechanical methods
▪ Rear the silkworm under a nylon mosquito net during
peak infestation period (December to March), which
ensures 80-90% control.
▪ During the transfer of late-stage worms, remove the fly
eggs from the integument of the silkworm larvae with the
help of forceps.
▪ Collect the destroy uzi maggots which come out at three
days after spinning in the Jali (mountage).
▪ Install electricity operated stifling chambers for cocoons
to check the emergence of uzi maggots from infested
cocoons at 3-5 days after spinning [5].
2) Cultural methods
▪ Plough or dig the soil in rearing plots to expose the
maggots /pupa for predators / strong sunlight to reduce
the infestation.
▪ Keep the rearing field clean and dust with bleaching
powder during rearing.
▪ Avoid rearing of muga silkworms continuously
(monocropping) from December-April to minimize the
uzi fly infestation [10].
3) Biological methods
▪ Nesolynx thymus is an ecto-pupal parasitoid of uzi fly.
About 40-60 parasitoids develop on each uzi pupa.
▪ N. thymus is produced on house fly pupa. 50 ml of
parasitoid pupae are packed in a nylon net pouch (Rs
50/pouch). About 10,000 NT adults emerge from the
pouch.
▪ Release N. thymus between the 3rd-5th day of 5th instar @
2 pouches/100 dfls.
▪ After mounting of spinning worms, transfer the same
near mountages.
▪ After harvesting cocoons, keep the same pouches near the
manure pit [13].
4) Quarantine method
▪ Restrict the transport of seed cocoons from one location
and state to another to reduce the infestation (ex: private
cocoon markets/grainages/reeling units should be kept
under regular vigilance) [5].
Conclusion
Muga silkworm (Antheraea assamensis Helfer) is endemic to
Assam and adjoining areas in North-Eastern India and
naturally produces golden silk. Due to the high incidence of
diseases, pests, and variations in climatic conditions, the
production of muga silk has recently declined dramatically.
Especially,uzi infestation in muga silkworm is so high. So,
control of the uzi fly in muga silkworm is very important. The
control of the uzi fly through Intregated pest management is a
broad-based approach that integrates practices for economic
control of pests. IPM aims to suppress pest populations below
the economic injury level (EIL). IPM program will enhance
the long-term stability of the holdings over and provide long
term solutions of pests.
Acknowledgment
First of all, I would like to express my deepest thanks to Dr.
Debajit Borah for his constant guidance throughout the
research work and this research work would not have been
possible without his timely suggestions despite of his busy
schedule. I am grateful to assistant professor Aparupa
Borgohain and project scientist Dr. Sudipta Sankar Bora for
guidance and their extended help. Finally, to my heartfull
gratitude my loving friends Bhairab Das, Fazlil Ahmed,
Himshikhar Deka and my junior Jyotismita Saikia for the
Journal of Entomology and Zoology Studies http://www.entomoljournal.com
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moral support and encouragement throughout the research
work.
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