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ON
THE INSECT PESTS OF Aquilaria agallocha ( ROXB.)
D. Gurung, N. Dutta and P. C.Sharma
Divn. of Plant Protection
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Aquilaria agallocha Roxb. is a commercially
valuable evergreen tree species commonly known as Agar
(Hindi) and Sasi (Assamese). It is distributed in North
Eastern Region of India, Burma and extends through South
East of Asia upto Philippines. In India two species of
Aquilaria are found viz. A.agallocha Roxb. and khasiana
kallier. Out of the two species only A. agallocha is the
source of the resinous deposition known as Agar from which
a much priced agar oil is extracted. During a field trip
to Holongpara it was observed that A.agallocha is attacked
by several minor and major insect pests. One of the important
pest was Heortia vitessoides (Pyralidae: Lepidoptera)
Moore. which damage the leaf, vegetative buds and tender
shoots causing adverse affect on the growth of the tree.
Survey of literature revealed that the information regarding
this insect pest is very poor. Therefore it was felt that
the vital aspects of biology of this pest be studied in
view of the menace which may grow out of proportion in
near future, in natural forest and plantations. The adult
moth has a wing span of 27 to 35 mm. The fore wing is
primrose yellow with bluish black spots and bands. Hind
wing is white with bluish black marginal band. The head
and thorax of the adult is yellowish with orange yellow
abdomen. Eggs are laid in cluster on the ventral surface
of the leafand are arranged like fish scales. Each egg
is greenish yellow, dorsoventrally flattened with a slight
bulge in the middle and measures 0.3 to 0.5 mm. in diameter.
The first instar caterpillar is pale yellow and measures
3.4 x 4.0 mm. in size whereas the full grown caterpillar
is 20 x 4 mm. in size. The agile caterpillars are gregarious
in habit and live in shelters of leaves loosely tied together
by silken threads, which later on looks somewhat like
a tent ofa tent caterpillar. They fall to the ground on
slight disturbance, hanging by a silk thread. The early
instars skeletonise the leaf but the later instar completely
defoliates. The full grown larva stop feeding and descend
to pupate in the soil and the cocoon is made out of soil
litters. The obtect pupa is dark brown in colour and measures
12 x 4 mm, in size. The life cycle is completed in 22
to 26 days during June-July, and several over lapping
generations in a year has been noticed. So far no parasites
and predators have been noticed, but a polyhedral disease
was isolated and tested in crude form. Further works on
bionomics, life cycle and control measures are in progress.
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Copyright
© RFRI, 2002
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Re-Designed
by: Himanshu Mishra & Santanu Saikia
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