| Abstrakt: |
The Asian rice gall midge Orseolia oryzae (Wood-Mason) (Diptera: Cecidomyiidae) is a serious pest of rice (Oryza sativa L.) in India. Seven distinct biotypes of the Asian rice gall midge population have been characterized so far from different parts of India. Field experiments to identify the prevailing rice gall midge biotype were conducted at the Agricultural Research Station, Nellore during Kharif, 2015-16 to 2021-22. A set of 17 standard differentials representing five groups identified to characterize the prevailing gall midge biotype in the country provided by the Indian Institute of Rice Research (IIRR), Hyderabad were sown at Agricultural Research Station, Nellore, coinciding with the peak incidence of gall midge. From the results of over the years of testing, the gall midge population of Nellore is following the reaction pattern of biotype 6 (R-S-S-S-S) which was consistently non-infective/less virulent on the group I differentials viz., Kavya, W 1263 and ARC 5605 (Gm 1 gene for resistance) with nil or below 10 % plant damage and moderate to highly virulent on MR 1523 (Gm 11 gene for resistance) of group III with 10 to 40 % plant damage. But there were some variations within groups II and IV and the reaction of these groups was less stable over the years, they were resistant one year and susceptible in the next year. During 2015, group IV differentials viz., Aganni and INRC 15888 with Gm 8 gene for resistance showed resistant reaction with 10 and 5 per cent plant damage and during 2019 group IV differentials viz., INRC 3021 and Aganni with Gm 8 gene showed a highly resistant reaction, slightly deviating from the reaction pattern exhibited by biotype VI (R-S-S-S-S). Variations in reactions within a group and variation within one entry from one year to another made it difficult to classify the reaction pattern. However, during 2021 all the differentials including INRC 3021, Aganni, and INRC 15888 of group IV with Gm 8 gene were found to be susceptible with more than 10 per cent plant damage. Moreover, INRC 3021 is highly susceptible during 2015 and became highly resistant during 2019 and moderately susceptible during 2021. During 2021 group II differentials Phalguna and ARC 5984 showed a highly resistant reaction, deviating from the reaction pattern of biotype VI. While during 2015 and 2019 all the differentials in group II were found susceptible with more than 10 per cent plant damage. Further, continuous studies are needed to decrease in consistency of the results. [ABSTRACT FROM AUTHOR] |
