Tryporyza incertulas

ByDr. Girish Chandra

 

Tryporyza  incertulas

The Yellow Stem borer

(Lepidoptera: Pyralidae)

  

 

Host: This is primarily a pest of rice but also has been recorded to feed on maize and some wild grasses.

 

Damage: The larva feeds inside the stem and makes gallery causing dead heart in younger plants. The flowering plants show white head, i.e. panicles dry up and become whitish in colour. One larva can damage several tillers before maturing.

 

Life cycle: Adults show sexual dimorphism. Females are yellowish brown to orange yellow in colour, with wing span of 3.0 cm, one black spot in the middle of fore wing and tip of abdomen bearing yellowish to buff coloured anal tuft of hairs. Males are slightly smaller in size; have yellowish forewings containing 6-7 small blackish spots.  Eggs are oval, flattened and whitish in colour. Incubation period of eggs is 5-8 days. Larvae are pale yellow in colour with a brownish head, 20 mm long and bore into the stem near the node. They usually feed on the lower part of the stem and migrate from one plant to another to mature. There are 6 larval instars and larval development takes 20-27 days. Pupation takes place inside a whitish silken cocoon within the rice stem, near the root-stem joint. Before pupation larva cuts an exit hole on the stem, above the surface of water and covers it with a silken web as an exit for emerge. Pupal period is 9-10 days or longer in cold weather. Total life cycle takes about 45 days and 4-5 generations can be completed from April to October. 

 

Distribution: The pest is found all over the Indian subcontinent, SE Asia, China and southern Japan.

 

Control: Collection and destruction of egg masses and plants showing dead hearts helps to reduce pest population, particularly in nurseries. Burning of stubbles or ploughing the field after harvesting is a good cultural practice. Early or late planting is recommended in areas of heavy infestation.

 

            Spraying of the following insecticides: fenthion 0.05%, endosulfan 0.035%, endrin 0.025%, parathion 0.04% @ about 400 litres per hectare 2-3 weeks after transplanting and then every 20 days. Application of granules in the root zone of the following insecticides: Lindane 10%, diazinon 5%, carbofuran 5%, quinalphos 5% @ 2-2.5 kg a.i./ha at 20 days interval gives satisfactory  control of this pest.

 

            The following natural enemies keep the pest population under check and must be conserved: Egg Parasites: Tetrastichus schoenobii, Telenomus beneficiens, Trichogramma sp.   Larval parasites: Amauromorpha accepta schoenobii; Isotima javensis. Larval-pupal parasite: Trichomma sp.

 


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Identification and Management of Horticultural Pests


Features: Nipa
By (author): A.M. Ranjith

This book has been written, primarily due to my own felt need to have a comprehensive text book on the pests of horticultural crops and methods to manage it, in the integrated way. Due to the widespread use of digital color photography and the good resolution that you get in even the basic level digital cameras, it is possible to get good photos. It was thus more of a need to have a text book to teach the UG and PG students, that this book was written. It was also necessary that any practicing field level worker like officers of the state department of Agriculture and commodity boards, and every practicing farmer with an ability to read English text book, should be guided into the basic facts about the pests of crops. It is most likely that most of the information is available in this book itself, as pest of some other crop. It will then be possible to read on the pest in that , and manage the pest effectively using the latest techniques available to the crop management expert.
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