Biology and management of armyworm of cereals Mythimna separata walker

ARJUN RAYAMAJHI
PLP 06M 2017
DEPARTMENT OF PLANT PATHOLOGY
AGRICULTURE AND FORESTRY UNIVERSITY
RAMPUR, CHITWAN
Assignment presentationon
Biology and management of
Oriental Armyworm of cereals
Mythimna separata

Biology and management of Oriental Armyworm of
cereals Mythimna separate
Presentation outline
1. Introduction
1.1 Biology
1.1.1 Systematic Position
1.1.2 Distribution
1.1.3 Host plants / species affected
1.1.3 Marks of Identification:
1.1.4 Nature of Damage
1.1.5 Life Cycle:
1.2 Management
1.2.1 Mechanical and Physical Control
1.2.2 Cultural Method:
1.2.3 Biological Method:
1.2.4 Chemical Method:
2. Conclusion

Introduction
 The Oriental armyworm, Mythimna separate (Walker) is a noctuid moth whose larval
(caterpillar) stage is a serious pest of cereals, pasture and forage crops in Asia (Wright,
& McNeil, 1988).
 Its Common names for the pest include: southern armyworm, sorghum armyworm,
army caterpillar, ear-cutting caterpillar and paddy cutworm (Sharma & Davies,
1983).

Systematic Position
Phylum – Arthropoda
Class – Insecta
Order – Lepidoptera
Family – Noctuidae
•Genus – Mythimna
Species – separata

Distribution
In Nepal, their damages have been recorded in many parts of the
country such as Palpa, Argakhanchi and Gulmi districts (Rana &
Plumb, 1973), Kavre and Sindhupalchowk districts (Rana, 1975)
and Nuwakot and Rasuwa districts (Joshi, 1978).
Anonymous (1976) reported M. separata also epidemic to maize crops
in Jumla, Humla, Bajhang, Lamjung, Rasuwa, Nuwakot, Syangja,
Kaski, Nawalparasi, Chitwan, Makwanpur, Bara, Parsa, Sarlahi,
Mahottari, Dhanusa, Kathmandu, Bhaktapur and Lalitpur districts.
In Nepal, winter maize is more susceptible to this pest (Shivakoti &
K.C., 1981).

Figure 1 Distribution of Mythimna separata in worldwide (Source:CABI Plantwise)

Figure 2 Distribution of Mythimna separata in South Asia (Source:CABI Plantwise)

Host plants / species affected
 Brassica rapa subsp. chinensis (Chinese
cabbage)
 Brassica rapa subsp. oleifera (turnip rape)
 Brassica rapa subsp. rapa (turnip)
 Cyperus rotundus (purple nutsedge)
 Echinochloa colona (junglerice)
 Echinochloa crus-galli (barnyard grass)
 Eleusine coracana (finger millet)
 Eleusine indica (goose grass)
 Hordeum vulgare (barley)
 Linum usitatissimum (flax)
 Nicotiana tabacum (tobacco)
 Oryza sativa (rice)
 Panicum antidotale (elbow grass)
 Panicum miliaceum (millet)
 Pennisetum glaucum (pearl millet)
 Pennisetum purpureum (elephant grass)
 Phaseolus (beans)
 Saccharum officinarum (sugarcane)
 Secale cereale (rye)
 Setaria italica (foxtail millet)
 Sorghum bicolor (sorghum)
 Sorghum halepense (Johnson grass)
 Triticum (wheat)
 Triticum aestivum (wheat)
 Urochloa mutica (para grass)
 Zea mays (maize)
(Source: CABI plantwise)

cereals Mythimna separata
Marks of Identification:
 The adult moths are stoutly build and
pale brown in colour.
 Forewings are greyish yellow
 Hindwings are grey in colour with dark
external margin.
 Antennae are thread-like.
 Mature larvae are 3–4 cm long and green
to pink in colour and provided with
longitudinal light grey to black
stripes running along the entire length of
their bodies.
 The head is brown to orange with an A
marking .

Nature of Damage
The caterpillars are damaging stage
In early stages, the caterpillars feed on tender leaves in central whorl
of the plant.
Later stages, they are able to feed on older leaves. In case of severe attack,
they defoliate leaves and the field looks as grazed by cattle.
The army worm feeds during dawn and dusk period as it is shy of sunlight.
Fourth and fifth instars larva are the major damaging stages and defoliate
the maize crop (Neupane et al., 1992).
These larvae not only feed the leaves but also damage the inflorescences,
ears, growth points and finally the grains and finally caused a heavy
decline in yield (GC & Keller, 2013).

Damage of rice plants by Mythimna separata

Life Cycle:
Eggs:
Eggs are laid in cluster, consisting of approximately 500 eggs
The young caterpillars hatch from the eggs in 4-5 days.

Larvae:
After hatching the caterpillars starts feeding on the leaves of the
seedlings.
Generally the caterpillars move in swarm from one field to the other.
The caterpillars are fully grown in about 15 days and measures 3-5
cm in length.

Pupae:
pupates in soil at a depth of 3–5 cm, but sometimes it may pupate
under dry leaves or on the stubbles or fresh tillers.
The pupae are yellowish brown and shiny, and pupal period varies
from 10 to 13 days.

Adult:
the life cycle is completed in about 30-35 days which is repeated
several times each year.

Management
Mechanical and Physical Control
Barriers can be constructed to divert migrating M. separata larvae.
kerosene can be poured in M. separata's path.
Egg masses or larvae can be hand-picked from seedbeds or a
young crop.

Cultural Method:
Before planting:
 Avoid following rice after crops of maize; follow with a food or forage
legume.
 Weed the field.
During growth:
 Weed crops, especially removing grass species.
 Put ducks in the fields to find and eat the larvae at the base of the
plants or in the soil.
 Place perches in the fields for insect-feeding birds to use.
 Alter water levels to drown pupae, and to limit spread of larvae
between plants.
After harvest:
 Plough the field after harvest, burying the stubble, preventing mature
larvae from pupating, and to expose the pupae buried in the soil.

Biological Method:
Ducks are often raised in rice areas and can be herded into
damaged fields to feed on M. separata larvae.
Introduction of Apanteles ruficrus, Sarcophaga
orientaloides and Exorista fallax is quite helpful in
controlling the destruction caused by the caterpillars since,
these insects parasitise the caterpillars.
Sparrows and crows act as predators of this pest.

Chemical Method:
Spray of chlorpyriphos 20 EC @ 2.5 litres/ha or quinalphos 25
EC @2.0 litres/ha or @ 1.0 litres/ha or dichlorvos 76 SL 600
ml/ha on the paddy crop during evening hours
Dusting of chlorpyriphos 1.5 % D @ 30 kg/ha controls this pest.

Conclusion
The armyworm, Mythimna separata Walker is the
potential insect pest of cereals, causes a severe damage
on the vegetative and reproductive stages of these plant.
Timely identification and adoption of proper
management is key for minimizing the loss .
Management by adopting a tool of integrated pest
management is one potential option to reduce the
pesticide in crop fields.

Biology and management of armyworm of cereals Mythimna separata walker

Biology and management of armyworm of cereals Mythimna separata walker

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