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Rice Hoppers and Associated Virus Diseases in Nepal
Nepal is endowed with rich diversity in land races of rice and also some wild rice species. Some of them are known for their resistance to insect and diseases, including rice hoppers and viruses. Nepal has so far released 68 improved rice varieties for different domains. With the introduction of improved varieties incidences of insect and diseases increased. Leafhoppers and planthoppers are among the rice insects of economic importance in Nepal. Till a decade ago, rice gundhi bug used to be the most important insect of rice. Now, hoppers have become more important. Of leafhoppers, green leafhopper (Nephotettix nigropictus), white leafhoppers (Cofena spectra) and zig zag leafhopper (Resilia dorsalis) are the common ones. Of them, N. nigropictus was found to transmit rice dwarf phytoreovirus, and N. virescens to transmit rice tungro bacilliform badna virus and rice tungro spherical waikavirus in Nepal. Of planthoppers, brown planthopper (BPH) (Nilaparvata lugens) and white-backed planthopper (WbPH) (Sogatella furcifera) are the major ones. Isolated outbreaks of BPH have been recorded from 1977 to recent past years and of WbPH in 1982. However, no virus diseases associated with BPH and WBPH have been recorded in Nepal though some yellow syndrome in large areas has been reported from BPH occurring area (Chitwan) for the last couple of years. It is worth to note that IPM-FFS (farmers’ field school) approach was adopted in 1997 in rice after the outbreak of BPH in Chitwan district. Farmers are practicing wetting and drying of rice fields for the management of BPH. Other management practices recommended include use of biopesticides, predators, light traps, chemicals and resistant varieties. With the objective of monitoring rice planthoppers and associated rice viruses Nepal in 2011 joined “Collaboration network for the management of migratory rice planthoppers and associated virus diseases of rice in Asia” - a regional project of Asian Food and Agriculture Cooperation Initiatives (AFACI), Korea.
