The rice caseworm is a pest that commonly affects rice crops and is mostly found in rice-growing regions worldwide. The larvae of the rice caseworm feed on the leaves of rice plants causing defoliation, yield loss and even crop failure which can lead to significant damage to the rice crops. Paddy at seedling and vegetative stages are the most preferred host of rice caseworms. It is commonly found in irrigated and rainfed wetland rice fields with poor drainage areas. The larvae can be identified by its translucent green body, orange head with filamentous gills on the side of the body. Transplanting young seedlings favors the development of rice caseworms.
Type of Infestation
Larvae feed on the chlorophyll content of the leaves leading to defoliation, stunted growth and death of the affected plant.
Scientific Name: Nymphula depunctalis
Most Affected States
The Paddy case worm is found throughout India, but it is most prevalent in the rice-growing regions of West Bengal, Assam, and Bihar.
Symptoms of Rice caseworm
- The larvae consume the green tissue of the leaves, causing them to turn whitish and papery.
- By cutting the apical part of leaves, caterpillars create tubular cases around themselves that can float on water.
- Ladder-like leaf tissues can be seen on the infested leaves.
- In case of severe infestation, plant growth is completely reduced.
Control Measures
Rice Caseworms can be controlled by following the below mentioned cultural, Mechanical, Biological and Chemical methods.
Cultural Measures
Cultural control methods for managing Paddy case worm infestations include the following:
- Early planting can help rice crops avoid the peak activity period of caseworm moths.
- Draining rice fields for 5-7 days can effectively kill caseworm larvae.
- Provide rice fields with wider hill spacing, typically 30 x 20 cm to experience less damage from caseworm.
- Applying nitrogen fertilizer at optimal dosages and using split applications can reduce the abundance of rice caseworms.
- Use a rope to dislodge the caseworm, causing them to fall on the ground and subsequently drain the water, gather the cases and destroy them.
Mechanical Measures
- Mix 400 ml of kerosene with 10 kg of sand and apply the mixture to the stagnant water. Then use coir rope for dislodging the caseworms in water mixed with kerosene.
Biological Measures
- Release natural predators such as larval parasitoids, Elasmus sp., Apanteles sp., Bracon sp., and pupal parasitoids, Pediobius sp., Apsilops sp., Eupteromalus parnarae to control the rice caseworms population.
- Also encourage biocontrol agents like hydrophilid and dytiscid water beetles to feed on the larvae of caseworms and spiders, dragonflies, birds to feed on the adult caseworms.
Chemical Measures
- Coromandel phendal is a broad-spectrum insecticide, which has a strong pungent odour that prevents adult caseworm moths from laying eggs. It contains a penthoate 50% EC and when used at the rate of 2 ml per liter of water can effectively control rice caseworms.
- Ekalux Insecticide is another broad-spectrum insecticide that can be effective in controlling rice case worm infestations. It contains Quinalphos 25% EC. The recommended dosage is 2 ml per liter of water.
