Stem Borer: Chilo partellus
It is the most destructive pest of maize and Sorghum in
Srilanka, India, Pakistan, Afghanistan, Uganda, Central and East Africa.Pest
is found in throughout India.
Nature of damage
- The young larvae first feed on the leaves, making a few shot holes
and then bore their way downwards through the central whorl as it opens.
- More shot holes become visible, indicating an earlier attack and the
plant also shows dead-hearts. Caterpillars damage maize by boring into
the stems, cobs or ears.
- Stem borer infestation results in pinhole damage in the leaves initially
and "dead hearts" subsequently.
- The insect breeds actively from March-April to October and for the
rest of the year it remain in hibernation as a full-grown larva in maize
and sorghum stubble, stalks or unshelled cobs.
- The larvae pupate sometime in March and emerge as moths in the end
of that month or in early April.
- They are active at night, when they mate and lay eggs on the underside
of the leaves of various host plants, particularly the early crops of
maize and sorghum grown as fodder.
- The eggs are flat, oval, and yellowish and are laid in overlapping
clusters each containing up to 20 eggs. A female lays over 300 eggs
during its life-p of 2-12 days, and the eggs hatch in 4-5 days in
- The larva become full-fed in 14-28 days passing through six stages
and after making a hole in the stem pupates inside it.
- The life cycle is completed in about 3 weeks and there are probably
5 generations in a year. The full-grown caterpillars of the last generation
hibernate in stubble, stalks, etc, and remain there till the next spring.
Management Of Stem Borers
- Pest management strategies viz., cultural, biological, host plant
resistance, chemical and integrated pest management for maize stem borers
can be practiced to effectively control both stem borers Chilo Partellus
and Sesamia inferens.
- Collection and burrying stubble and stalks or ploughing and destroying
crop residue, removal of infested plant parts or infested plants at
hoeing are recommended.
- Growing maize in association with various legumes significantly reduced
C. partellus damage in maize. Also intercropping maize with soybean
gave a considerable reduction in C. partellus and S. inferens
and 9.2% increase in grain weight per plant. Therefore intercropping
has a great potential in reducing the pest incidence.
Exploitation of ovipositional behavior
- The ovipositional behavior of C. partellus could be exploited
for its management.
- Clipping of lower leaves of maize (up to fourth) on which most of
eggs of C. partellus are laid, reduced damage to some extent.
- As this practice may not be practicable in a large scale, they recommended
earthling-up of the crop to bury the lower leaves as a possibility for
reducing initial infestation.
- Intensive screening to identify resistance sources against (C. partellus
yielded an important germplasm source. Antigua Gr. 1 and few breeding
- Sources of tolerance to S. inferens have been identified. These materials
are currently being used in Directorate of maize Research and also in
other centres breeding programs.
- At this time, however, stem borer resistant cultivars / hybrids have
yet to be released in the semi arid tropics. Further more, the work
on the screening for resistance is being done extensively and continuously
and there is every possibility of identifying sources of resistance
to borers and development of resistant hybrids/varieties.
- Many natural enemies have been reported to attack C. partelllus.
- Among the parasitoids reported, Trichogramma spp. as egg parasitoids
and Aphanteles favipes and T. Chilonis and larval parasitoids
- T. cllilonis has been found parasitising egg masses of C.
partelllus upto 70% . A. flavipes is the most dominant and
most widely distributed larval parasitoid of C. partellus in
India with a parasitisation ranging from 5.3 - 42.8%.
- Even though a number of natural enemies have been reported on maize
borers, but in general, the efficiency of natural enemies in particular
farming environments is not known.
- The scope for successfully controlling maize stem borers with natural
enemies is limited by the short cropping period and the lack of continuous
habitat for natural enemies.
- Seed treatment with carbofuran 35 ST dust.
- Seed treatment with carbofuran (40F)@ 2.5g/kg of seed was also
found effective against S. inferens.
Effective control schedule
- 1st Foliar application of Endosulfan 0.1% at 15 days after
- 2nd application of 4% granules al 15 kg/ha a fortnight
later against C. partellus.