''Parapoynx stagnalis'', the rice case bearer or rice caseworm, is a species of

moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...

in the family Crambidae. It has a wide distribution and is found in

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, South-East Asia,

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, southern

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(

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and

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(the

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and

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Description

The life cycle is completed in about 35–40 days. The length of the forewings is 16 mm. Adult has whitish wings with pale brown wavy markings. There are two black comma-shaped marks on each forewing. Male can be identified by narrow and uniform abdomen, whereas female abdomen is widest at the middle but tapering posteriorly. Female usually lay 150 eggs and first instar larvae emerge after a week. Final larva emerge after 20 days, and reaches its maximum length of 10-12mm. The moth has six larval instars. Due to branched tubular gills, caterpillars can respire in aquatic media. Therefore, instar can disperse through water. Pupation occurs when the pupal case is attached to the leaf sheath above the water level. After a week of pupation, adult emerges.

Ecology

As its common name implies, rice caseworm is one of the major pests of

rice Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima ''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...

throughout the world. Larvae is the infective stage, where they cut leaf tips to make leaf cases. The infestation can be characterized by ladder-like skeletonized tissues in leaves. Larvae completely consume the leaf blade, where only mid rib is visible. Surrounding weeds are the secondary hosts for the moth.

Control

Eggs of rice caseworm can be controlled by using snails. Larvae can be controlled by using many natural predators like water beetles of the families

Hydrophilidae Hydrophilidae, also known colloquially as water scavenger beetles, is a family of beetles. Aquatic hydrophilids are notable for their long maxillary palps, which are longer than their antennae. Several of the former subfamilies of Hydrophilidae ...

and Dytiscidae. Pupal stages can be eradicate by the introduction of ''

Pediobius ''Pediobius'' is a genus of hymenopteran insects of the chalcid wasp family Eulophidae. Like their relatives, the larvae of these diminutive wasps are parasitoids of various arthropods (mainly insects). Some ''Pediobius'' are used in biological ...

'' and '' Apsilops'' species. Adult moths are daily meal for many spiders, insect eating bird species and dragonflies. Other than biological methods, many traditional methods such as reducing the water level of paddy fields, crop rotation, crop sanitation, pruning, light traps and hand picking are also effective. Chemicals such as

DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...

, BHC or Carbaryl can be used in required concentrations.

References

External links

Yield loss in rice caused by the caseworm Nymphula depunctalis Guenee (Lepidoptera: Pyralidae).Natural Enemies of the Rice Caseworm Nymphula Depunctalis (Guenée) (Lepidoptera: Pyralidae)Research on Nymphula depunctalisYield loss in rice caused by the caseworm Nymphula depunctalisEffect of Stocked Fish on Rice Leaffolder Cnaphalocrocis medinalis and Rice Caseworm Nymphula depunctalis Populations in Intensive Rice Culture
Moths described in 1852 Acentropinae Moths of Madagascar Moths of Japan Lepidoptera of Mozambique Lepidoptera of West Africa Insects of Malawi Moths of Europe Moths of Africa {{Acentropinae-stub