Seasonal variation in population and biochemical contents of brown planthopper, Nilaparvata lugens (Stål)

Aim: The present study was undertaken on population dynamics and estimation of protein, water-soluble carbohydrates and glycogen contents in the brown planthopper, Nilaparvata lugens to explore their migratory behaviour. Methodology: Brown planthopper populations were monitored and collected using sweep nets from 23rd standard meteorological week (SMW) to 47th SMW during 2017 and 2018 rainy seasons to understand population dynamics of the pest. The protein, water-soluble carbohydrates and glycogen contents were estimated from the pest samples collected during 36th to 44th SMW in 2017 and 2018 rainy seasons. Results: Brown planthopper population were not observed in rice farm during 23rd SMW to 28th SMW during two years of study. However, macropterous form of the pest first appeared in the farm during 29th SMW and peaked during 43rd SMW. Thereafter, population declined and disappeared after 47th SMW during both the years. Water-soluble carbohydrates and glycogen contents varied significantly different weeks which remained low during 36th-39th SMW, however, increased gradually towards the end of the rainy season 2017 and 2018. On the other hand, protein content significantly varied among different weeks unlike the trend of water-soluble carbohydrates and glycogen. Interpretation: The study revealed the absence of brown plant hopper during summer season preceding rainy season, and the accumulation of bio-chemical compounds towards the end of rainy season under Delhi environment is perhaps suggestive of migration of the pest from unknown areas during rainy season to Delhi and likely preparedness of the pest for emigration to safer areas from Delhi, respectively.

Future scenarios of rice brown plant hopper Nilaparvata lugens (Stal.) under changing climate

Abundance of brown plant hopper (BPH) Nilaparvatalugens (Stål) (Delphacidae: Homoptera) is modulated by prevalent weather conditions of rice growing seasons and locations. Categorization of BPH adults caught in light traps (nos/week/trap) into low, moderate and high and formulation of criteria accounting weather variables [maximum/ minimum/ mean temperature (ÚC), morning/evening/mean relative humidity (%), rainfall (mm) and sunshine hours (h/day) and wind speed (km/h)] during kharif of2011-16 for four locations viz., Ludhiana (Punjab), Chinsurah (West Bengal), Raipur (Chhattisgarh) and Aduthurai (Tamil Nadu) with associated rules for weather based BPH prediction. Validation of BPH predictions for kharif 2017 indicated 96, 87, 73 and 61% accuracies in respect of Aduthurai (TN), Raipur (CG), Ludhiana (PB) and Chinsurah (WB). Future weather based predictions of BPH based on climatic projections of representative concentration pathway (RCP) 4.5 for 2020, 2050 and 2080 indicated absence of high population at Chinsurah (WB) during all time periods of 2020-2080. Progressively reducing BPH abundance from past (2011) to all future periods was noticed at Aduthurai (TN). ‘High’ BPH from 2020 and beyond over 2011 and 2016 at Raipur (CG) and reducing ‘high’ but increasing ‘moderate’ category between 2020-2050 but the reverse in 2080 at Ludhiana (PB) were predicted indicating requirement of continued monitoring strategies put in place at these locations. The observed spatial variability of climate change influence on BPH implied a need for zonation mapping of rice insects including BPH for India.

Seasonal Abundance of Brown Plant Hopper, Nilaparvata lugens (Stal) in Rice and Correlation of Abiotic Factors Under Pune Region

An agro-meteorological investigation was undertaken on “Crop weather pest relationship and validation of DSSAT model for rice varieties under different transplanting dates’’ during kharif, 2016 and 2017 at Agricultural Research Station Farm, Vadgaon Maval, Dist. Pune, under Mahatma Phule Krishi Vidyapeeth, Rahuri, University. An experiment was laid out in split plot design with three replications. The treatment comprised of four sowing dates viz., S1 : 26th MW (25 June-1 July), S2 : 28th MW (9 July-15 July), S¬3 : 30 MW (23 July-29 July) and S4 : 32nd MW (06 August -12 August) as main plot treatments and four varieties viz., V1: VDN-99-29 (Phule Samruddhi), V2 : VDN-3-51-18 (Indrayani), V3 : IET-13549 (Bhogavati) and V4 : RDN-99-1 (Phule Radha) as sub plot treatments. Average number of brown plant hopper showed highly significant positive correlation with maximum temperature (0.902**, 0.627**), positive correlation with morning humidity (0.534, 0.789*), evening humidity (0.678*, 0.551) and bright sunshine hours (0.345, 0.483). While minimum temperature (-0.567, -0.543) and rainfall (-0.302, -0.307) showed negative correlation with brown plant hopper on 26th MW, 28th MW, 30th MW and 32nd MW transplanting dates. During both the years of 2016 and 2017, respectively.

Broadening Genetic Base of Rice and Identification of Pre-Breeding Lines for Resistance to Brown Plant Hopper, Nilaparvata lugens (Stål.)

Pre-breeding includes basic research to achieve wide crosses and facilitate the use of exotic materials or wild relatives for both qualitative and quantitative traits. The main objective is to provide breeders with more ‘attractive’ PGR that are easier to use, i.e. resistance sources in acceptable genetic background; or inbreeding tolerant forms of out crossing species for hybrid breeding. Forty seven pre-breeding lines were evaluated against Brown Plant Hopper under glasshouse condition over a period of two years (2018 and 2019). Out of these, two pre-breeding lines were moderately resistant to BPH having score 3. Two pre-breeding lines were moderately susceptible to BPH having score 5, five lines were susceptible having score 7 and rest thirty nine pre-breeding lines were highly susceptible to BPH with a score of 9.

Transmission Effectivity of Rice Yellow Stunt Disease by Imidacloprid-Resistant and Susceptible Brown Plant Hopper

The brown plant hopper (BPH) is a major pest of rice and as a vector of Rice ragged stunt virus (RRSV) and Rice grassy stunt virus (RGSV). Curently, numerous rice yellow stunt disease symptoms are found in the field that caused by the single and simultaneous infection of these two viruses. Brown plant hopper population correlate with the incidence and severity of the disease. Misuse of insecticides, would cause of BPH resistances to imidacloprid. This study aimed to investigate the ability of BPH imidacloprid-resistant and susceptible to transmit of rice yellow stunt disease on rice plants. The variables tested were the acquisition period, inoculation period, number of infesting BPH, and lifespans of the viruliferous BPH that used in this research. Experiments were set as separated Completely Randomized Design with 10 replications for each treatment within an experiment. The results showed that both resistant and susceptible BPH to imidacloprid was able to transmit the virus to healthy plants. The acquisition and inoculation period test showed the BPH could transmit the virus with the shortest acquisition time for 30 minutes followed 24 hours of inoculation, as well as the acquisition time of 10 days with the shortest inoculation time for 30 minutes. Based on the incubation time, symptoms variation, and disease severity, susceptible BPH were more effective in transmitting rice yellow stunt disease than imidacloprid-resistant BPH. Single imidacloprid-resistant or susceptible BPH was proven able to transmit rice yellow stunt disease to healthy plants during its lifespan. Lifespans BPH viruliferous of imidacloprid-resistant were shorter than susceptible, which was 16 days for resistant BPH and 21 days for susceptible BPH.

Screening of Some Rice Germplasm for Resistance to Leaf Blast and Brown Plant Hopper

Blast is a major rice disease that can affect rice plant during all growth stages, wherein causing drastic yield loss globally. Host-plant resistance has been the most practical and cost effective approach to control insect pests and diseases in crops. Therefore, eighty (80) rice genotypes were screened for resistance to the leaf blast and brown plant hopper at Hybrid Rice Evaluation Centre, Gudalur, The Nilgiris District, Tamil Nadu, India. The study site is known as blast and brown plant hopper (BPH) hot spot in India. The genotypes were evaluated according to the standard evaluation system for rice. The results revealed that nineteen (19) genotypes namely; CB08504, CB13506, CB14528, CB14681, PR114, ORJ1141, CR3868-225-1-2-2-5, MTU1156, NDR2111-13-1, PAU3835-12-1-1-2, MTU1157, HKR08-1, CT16658-5-2-3SR-2-1MMP, IR10A136, CB14149, CO(R) 49, Ciherang, IR11A294 and EC578527 showed resistant reaction and 27 genotypes were found to be moderately resistant to the leaf blast disease. None of the genotypes was immune to BPH reaction. Four (4) genotypes were resistant, and twenty-three (23) were moderately resistant. The genotypes viz., CR3868-225-1-2-2-5 and NDR 2111-13-1 which were resistant to leaf blast showed moderate resistance to BPH. Genotypes like HHZ 17-DT-6-Sal3-DT 1, BRR 0015, PAU 3842-60-5-1-3, Vanjinathan and EC 465120 were moderately resistant to both blast and BPH. These genotypes identified may be utilized as genetic sources for multiple resistant genes in rice improvement.

Molecular identification of three entomopathogenic fungi infecting the brown plant hopper pest in Indonesia

Background Brown plant hopper (Nilaparvata lugens Stal.) a very damaging pest to rice crops. One of the efforts to control it is the use of entomopathogenic fungi (EPF). Three fungal local isolates found in Indonesia were effective in controlling the brown plant hopper pest. This study aimed to molecularly identify the 3 fungal isolates. Molecular identification is very important to get the exact identity of these fungi. The accuracy of EPF identification will greatly determine the success of control. Molecular identification is based on a partial genetic analysis of the internal transcribed spacer (ITS) locus of ribosomal fungal DNA. Result Morphology of the local isolates named J22 and J60 were identified as Paecilomyces sp., while the isolate J34 was identified as Beauveria sp. The results of molecular identification of the isolates J22 and J60 were identified as the fungi Lecanicillium saksenae and Simplicillium sp., while isolate J34 was identified as Myrothecium sp. The results of literature search showed that the 3 fungi have never been previously reported to infect the brown plant hopper. Conclusion In Indonesia, 3 types of EPF, namely L. saksenae, Simplicillium sp., and Myrothecium sp., were found having the potential to control the brown plant hopper pest.

EVALUATION OF THE EFFECT OF ELEVATED CO2 ON BIOEFFICACY OF BUPROFEZIN INSECTICIDE AGAINST BROWN PLANT HOPPER, Nilaparvata lugens (STÅL)

The effect of elevated CO2 (570±25ppm) on the brown plant hopper (BPH) population, rice yield parameters, and efficacy of buprofezin (0.05%) in terms of spray volume was studied in an open top chamber (OTCs) during rainy season 2017 and 2018. The pest population was observed to be higher during 2017 compared to the rainy season of 2018. Under elevated CO2, rice plants had more vegetative tillers (18%) and reproductive tillers (22.1%), but there was a decrease in 1000-seed weight (11.2%), seed number per panicle (3.91%), and grain yield (18.8%) in comparison to ambient CO2 grown rice plants. The spray volumes of 700, 600, 500, and 400 l/ha each caused higher BPH mortality under ambient CO2 compared to elevated CO2. A spray volume of 500 l/ha did not prove as effective under elevated CO2 as under ambient CO2. Lower efficacy of spray volume of 500 l/ha under elevated CO2 could be ascribed to higher canopy size under elevated CO2 due to higher tillering. Increased crop canopy size under elevated CO2 may thus require higher spray volume to ensure proper coverage. Results of the study suggested a need to revise spray volume recommendations to facilitate effective management of BPH under climate change.

Compatibility of Entomopathogenic Fungi with Neonicotinoids for the Management of Brown Plant Hopper of Rice, Nilaparvata lugens stal. (Delphacidae: Hemiptera)

Background: Rice is the staple food of Indians and it is attacked by more than 100 species of insects. Among all, brown planthopper (BPH), Nilaparvata lugens (Stal) (Hemiptera: Delphacidae) is one of the major sucking insects, which can cause appreciable damage by sucking sap on other hand transmitting viral diseases. Farming community using several insecticides for managing the BPH. However, continuous use of these insecticides causes health hazards and environmental pollution and also leads to development of insecticide resistance. Keeping this view in mind, the present investigation has been planned with combined use of fungal formulations and commonly used neonicotinoid insecticides in rice eco system for managing BPH. Methods: This experiment was carried out in two parts, one is studied the compatibility between neonicotinoids (Thiamethoxam 25 SG and Dinotefuran 20 SG) and entomopathogenic fungi (Beauveria bassiana, Metarhizium anisopliae and Lecanicillium lecanii =Verticillium lecanii) by following the standard poison food technique. Second one is after studied the compatibility between neonicotinoids and entomopathogenic fungal agents, inhibitory studies were conducted under glasshouse conditions.Result: The study revealed that two tested insecticides affected the radial growth of fungi partially at all the three concentrations (0.5RC, RC and 1.5RC). At recommended concentration (RC), dinotefuran 20 SG @0.4 g/l was found to be slightly harmful to all three fungi (20% - 35% reduction of the growth of the fungus) and thiamethoxam 25 SG @ 0.25g/l appeared to be slightly harmful to B. bassiana and M. anisopliae and moderately harmful to L. lecanii (35-50% reduction of the growth of the fungus). Thiamethoxam 25SG alone recorded 65.0% mortality of BPH and when mixed with B. bassiana and M. anisopliae gave 86.25% and 81.25% mortality of BPH respectively under glass house conditions. Similarly, Dinotefuron 20 SG alone could gave 98.75% mortality of BPH.