Antixenosis and Tolerance of Rice Genotypes Against Brown Planthopper

Nine genotypes were evaluated under greenhouse conditions for antixenosis and tolerance against brown planthopper (BPH, Nilaparvata lugens Stål). In antixenosis studies, proportion of insects settled on a test genotype in relation to the susceptible control TN1 was recorded, with significantly lower proportion of nymphs (55.22%–59.18%), adult males (60.33%–60.75%), and adult females (80.56%– 79.26%) settled on RP2068-18-3-5 and Ptb33 in relation to those on TN1. Based on number of feeding sites, the test genotypes were ranked in order from the highest to the lowest as RP2068-18-3-5, Ptb33, MR1523, Rathu Heenati, Sinnasivappu, ARC10550, MO1, INRC3021 and TN1. The order was exactly reverse in terms of fecundity expressed as number of eggs laid per female. In tolerance studies, days to wilt, functional plant loss index and plant dry weight loss to BPH dry weight produced were recorded. RP2068-18-3-5, Rathu Heenati and Ptb33 performed better than the other test genotypes. These results helped in relative quantification of BPH resistance levels in the genotypes. RP2068-18-3-5, a new effective source of BPH resistance, can be used in resistance breeding after tagging of resistant genes/QTLs linked to different parameters of antixenosis and tolerance with selectable molecular markers

Effect of weather variabilities on dispersion pattern of Nilaparvata lugens (Stål) (Homoptera: Delphacidae) in paddy field

Field experiments were conducted to find out the impact of weather factors and crop phenological stages on the dispersion pattern of brown planthopper (BPH), Nilaparvata lugens (Stål) in paddy during kharif 2019 and 2020 at three paddy crop phenological stages like the active tillering stage (IV week of July to III week of August), panicle bearing and grain filling stage (IV week of August to III week of October) and grain maturity stage (IV week of October to IV week of November). Weather factors in relation with mean BPH population were subjected to multiple regression and correlation analysis. The dispersion patterns were studied by regression models using Index of dispersion, Elliott’s law, Taylor’s Power Law and Iwao’s patchiness regression model. Maximum population of BPH was observed during panicle bearing and grain filling stage at 108 days after transplanting. The BPH counts were fitted to negative binomial which indicated aggregated distribution in the field and most of the weather parameters like temperature, evening relative humidity and wind speed is negatively correlated during this stage. During active tillering and grain maturity stage, Poisson distribution pattern of BPH population in the field was observed which showed random distribution

Donors for Resistance to Brown Planthopper Nilaparvata lugens (Stål) from Wild Rice Species

Out of 1 989 wild accessions sown in seed boxes for screening, only 1 003 wild accessions with good germination were screened against brown planthopper (BPH), Nilaparvata lugens (Stål) under greenhouse conditions. The collection comprised of accessions from 11 wild species and African cultivated rice. The germplasm was screened for BPH following standard seed box screening technique in the greenhouse. As many as 159 accessions were identified as resistant during the year 2012 based on one year screening. A selected set of BPH resistant accessions were screened again during 2013. Based on the two years screening, seven accessions of O. nivara (AA), one accession of O. officinalis (CC), seven accessions of O. australiensis (EE), five accessions of O. punctata (BB and BBCC) and nine accessions of O. latifolia (CCDD) were confirmed to be resistant to BPH. So far no BPH resistance genes have been identified and designated from O. nivara and O. punctata, hence these may act as new sources of resistance

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Not AvailableThe rice brown planthopper (BPH) Nilaparvata lugens (Sta°l) is one of the major pests of rice across Asia. Host-plant resistance is the most ecologically acceptable means to manage this pest. A rice breeding line RP2068-18-3-5 (RP2068) derived from the land race Velluthacheera is reported to be resistant to BPH populations across India. We identified a new R gene [Bph33(t)] in this line using advanced generation RILs derived from TN1 9 RP2068 cross through phenotyping at two locations and linkage analysis with 99 polymorphic SSR markers. QTL analysis through IciMapping identified at least two major QTL on chromosome 1 influencing seedling damage score in seed box screening, honey dew excretion by adults and nymphal survival. Since no BPH R gene has been reported on chromosome 1, we designate this locus as a new gene Bph33(t) which accounted for over 20% of phenotypic variance. Scanning the region for candidate gene suggested two likely candidates a leucine rich repeat (LRR) gene and a heat shock protein (HSP) coding gene. Expression profiling of the two genes in the two contrasting parents and RILs showed induction of the HSP gene (LOC_Os01g42190.1) at 6 h after infestation while LRR gene did not show such induction. It is likely that the HSP represented Bph33(t).Not Availabl

Virulence of brown planthopper (Nilaparvata lugens) populations from South and South East Asia against resistant rice varieties

This study examines the utility of resistant varieties and their associated resistance genes against brown planthopper, Nilaparvata lugens (Stal), populations from South and South East Asia. A collection of 39 rice accessions that included resistant, tolerant and susceptible varieties and breeding lines were examined for performance against populations of N. lugens from India (4), Bangladesh (1), Myanmar (1), Vietnam (1), Indonesia (1), China (1), Taiwan (1), and the Philippines (2). Planthopper virulence varied between regions; however only 6 varieties were generally less damaged than the susceptible check Taichung Native 1 (TN1) among >= 50% of the test populations. Each of these 6 varieties contained multiple resistance genes. One further variety, also with multiple resistance genes, and a modern cultivar (possibly with the Bph3 gene) were moderately effective against the South Asian populations, whereas a traditional variety with the Bph6 gene was effective against South East Asian populations. Bph1, bph2, bph5, bph7, bph8, Bph9, Bph10 and Bph18 were ineffective against most planthopper populations. Bph20, Bph21, and Bph17 have potential to be used in resistance breeding in both South and South East Asia, whereas BPH25 and BPH26 have potential for use in South Asia. The results indicate that only a few of the currently available resistance genes will be effective in monogenic rice lines; but that pyramiding of two or more genes with strong to weak resistance could improve resistance strength and durability as apparent with the most resistant, traditional varieties. Strategies to avoid planthopper adaptation to resistant rice varieties are discussed. (C) 2015 Elsevier Ltd. All rights reserved