Cnaphalocrocis medinalis
Encyclopedia
The Rice Leafroller is a species of moth
of the Crambidae
family. It is found in south-east Asia
, including Hong Kong
, Sri Lanka
, Taiwan
, Thailand
and most of Australia
.
The wingspan
is about 16 mm.
The larvae are considered a pest on Zea mays, Oryza sativa
and Triticum, Saccharum and Sorghum
species.
The moth is very active, bright yellow or straw in colour with two distinct wavy lines in the fore wing and one wavy distinct line in the hind wing. It has a wing span of 15mm. Eggs are laid singly or in groups arranged in longitudinal rows on the undersurface of the leaves which are scaly white in color. Fecundity is about 56 eggs. Incubation period is 4-8 days. We find 5-6 larval instars, larval period is about 22-23 days. It pupates with in the infested leaf fold for a period of 6-7 days. The fully grown caterpillar is green in color and is 16.5mm long. The total life cycle completed in about 5 weeks.
All the stages of the crop is attacked by this pest. On hatching the newly hatched caterpillar cut the leaf edges and folds the leaf. When young seedlings are attacked it folds 3-4 adjacent plant leaves and scrapes the green matter so that the infested leaves appear white. A single caterpillar damages several leaves. The attacked plants dry up and it reduces the vigour of the plant. Ultimately the yield gets reduced. The yield loss may vary up to 10-50 per cent. It is more problematic at boot leaf stage.
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...
of the Crambidae
Crambidae
The Crambidae are the grass moth family of Lepidoptera . They are quite variable in appearance, the nominal subfamily Crambinae taking up closely folded postures on grass-stems where they are inconspicuous, while other subfamilies include brightly coloured and patterned insects which rest in...
family. It is found in south-east Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, including Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
, Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
and most of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
The wingspan
Wingspan
The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...
is about 16 mm.
The larvae are considered a pest on Zea mays, Oryza sativa
Oryza sativa
Oryza sativa, commonly known as Asian rice, is the plant species most commonly referred to in English as rice. Oryza sativa is the cereal with the smallest genome, consisting of just 430Mb across 12 chromosomes...
and Triticum, Saccharum and Sorghum
Sorghum
Sorghum is a genus of numerous species of grasses, one of which is raised for grain and many of which are used as fodder plants either cultivated or as part of pasture. The plants are cultivated in warmer climates worldwide. Species are native to tropical and subtropical regions of all continents...
species.
The moth is very active, bright yellow or straw in colour with two distinct wavy lines in the fore wing and one wavy distinct line in the hind wing. It has a wing span of 15mm. Eggs are laid singly or in groups arranged in longitudinal rows on the undersurface of the leaves which are scaly white in color. Fecundity is about 56 eggs. Incubation period is 4-8 days. We find 5-6 larval instars, larval period is about 22-23 days. It pupates with in the infested leaf fold for a period of 6-7 days. The fully grown caterpillar is green in color and is 16.5mm long. The total life cycle completed in about 5 weeks.
All the stages of the crop is attacked by this pest. On hatching the newly hatched caterpillar cut the leaf edges and folds the leaf. When young seedlings are attacked it folds 3-4 adjacent plant leaves and scrapes the green matter so that the infested leaves appear white. A single caterpillar damages several leaves. The attacked plants dry up and it reduces the vigour of the plant. Ultimately the yield gets reduced. The yield loss may vary up to 10-50 per cent. It is more problematic at boot leaf stage.