BPH Population Research Articles

Rice brown planthopper, Nilaparvata lugens (Stål) feeding behavior in relation to elevated CO2 and temperature

Feeding behavior of brown planthopper, Nilaparvata lugens (Stål) populations collected from different geographical regions Ludhiana, Nalgonda and West Godavari at three generations 1, 5 and 10 fed on rice plants grown under different CO2 and temperature levels 1) Ambient CO2@ 380±25ppm + ambient temperature (aCO2+aT), 2) Elevated CO2@500±25ppm + ambient temperature (eCO2+aT) and 3) Elevated CO2@500±25ppm + elevated temperature (eCO2+eT) in closed CO2 chambers was studied. Elevated CO2 + elevated temperature increased feeding rate of BPH nymphs while BPH adults showed declined feeding rate. BPH nymphal feeding rate increased with progressive generations while it decreased in BPH adults. Ludhiana adult BPH population showed higher honeydew excretion compared to West Godavari and Nalgonda populations. CO2 + temperature levels at progressive generations have varying effects on adults and nymphs of three BPH populations. Biochemical composition of rice plants grown under different CO2 levels revealed increased rate of soluble sugars, phenols and decreased rate of reducing sugars, soluble proteins, free amino acids, nitrogen, potassium, phosphorous in elevated CO2 + elevated temperature levels compared to ambient conditions. Increased feeding rate of BPH under elevated CO2 levels may be to compensate changes in host plant quality i.e., high soluble sugars and low nitrogen.

Does competition between Pardosa pseudoannulata and Menochilus sexmaculatus reduce the predation rate on brown planthopper?

Pardosa pseudoannulata and Menochilus sexmaculatus are classified as natural enemies of the brown planthopper or BPH (Nilaparvata lugens). This study aimed to determine the effect of differences in density on mortality and their predation rate in suppressing the BPH population. This study used a completely randomized design of 15 treatments and 3 replications. The treatments consisted of different densities of two predators (1, 2, and 3 individuals). The variables observed were predator mortality, predation rate, competition between predators, and competition behavior. The results showed that competition between predators at different densities was not directly related to predator mortality and the predation rate of joint predators. Predator density tended to increase the predation rate, especially on M. sexmaculatus (R=0.894), while the density of P. pseudoannulata and joint predators was moderate (Rpardosa=0.587, Rjoint=0.522). M. sexmaculatus won the competition when its population increased. Equal competition occurred in the composition of 1 P. pseudoannulata and 3 M. sexmaculatus (P1M3); in this composition, no deaths were found due to competition, with the predation rate reaching 86.7%. Cannibalism dominates intraspecific competition between individuals of P. pseudoannulata, while interspecific competition occurs between the two species, causing sub-lethal effects.

Nicotine-mediated dopamine regulates short neuropeptide F to inhibit brown planthopper feeding behavior in tobacco-rice rotation cropping.

The tobacco-rice rotation cropping (TRRC) is an ecologically friendly system that can both alleviate soil nicotine pollution and decrease the brown planthopper (BPH, Nilaparvata lugens Stål) fitness on rice. However, few studies on this green and effective rotational cropping system have been reported. In particular, the underlying mechanisms of TRRC on the significant reduction of field pest population at the molecular level is still unknown. Field investigation showed that BPH population decreased significantly in TRRC than in rice-rice successive cropping (RRSC) field. In addition, the short neuropeptide F (NlsNPF) and its receptor NlA7 of BPH had half-times lower levels in the TRRC field. Behavioral bioassay indicated a 1.93-fold increase in the number of salivary flanges of the dsNlsNPF group, while BPH fitness parameters, such as honeydew, weight gain, and mortality decreased significantly. Dopamine (DA) content in BPH decreased by ~11.1% under the influence of nicotine, and its presence increased the expression levels of NlsNPF and NlA7. Exogenous DA application eliminated the inhibitory effects of nicotine on BPH feeding and restored the fitness levels of its parameters. Independent application of either a mixture of dsNlsNPF with a nanocarrier or nicotine to the normal rice field revealed that the latter could produce better effects in combination with dsRNA. These findings confirmed that DA regulated NlsNPF to inhibit the BPH feeding behavior in TRRC. The results not only provided novel findings on the mechanism of pest-host interactions, but also presented new method for integrated pest management. © 2023 Society of Chemical Industry.

Incidence of dwarf disease and yield on Inpari 32 over two sequential seasons in Klaten, Central Java

Rice dwarf disease caused by Rice grassy stunt virus (RGSV) and Rice ragged stunt virus (RRSV) is frequently found in Indonesia. This disease is transmitted by brown planthopper/BPH (Nilaparvata lugens Stål). The infected plants become dwarfs and lead to reduced yields. The purpose of this study is to determine the number of BPH populations due to the occurrences of dwarf disease and yield on Inpari 32 rice over two sequential planting seasons in Klaten, Central Java. The observed parameters were dwarf disease symptoms, incidence and intensity of the disease, BPH population and its natural enemy, the vegetative growth, and yields. The analysis used in this study were descriptive analysis and linear regression. The results showed that, plant growth during the dry season was better than the rainy season based on plant height and tiller number. The average population of BPH in the dry season were 0.2–4 individual/hill which is lower than in the rainy season (0.43–4.4 individual/hill). The incidence and intensity of disease in the dry season were lower than rainy season. The higher incidence and intensity of rice dwarf disease in the rainy season caused a decrease in dry harvest yields and milled dry yields were 10.95% and 10.81%, respectively

Development and characterization of near-isogenic lines for brown planthopper resistance genes in the genetic background of japonica rice 'Sagabiyori'.

The brown planthopper (BPH: Nilaparvata lugens Stål) is one of the most destructive insects in rice production. The use of host plant resistance has potential to reduce damage caused by BPH. The heat tolerance japonica rice 'Sagabiyori', with superior grain quality and high soluble starch in the stem, is highly susceptible to damage by BPH. Here, to enhance its BPH resistance, we developed seven near-isogenic lines (NILs) carrying BPH2, BPH17-ptb, BPH32, BPH3, BPH17, BPH20, and BPH21 through marker-assisted selection and evaluated resistance to two BPH populations. Most lines were more resistant to the Hadano-1966 BPH population than Sagabiyori but were less effective against the highly virulent Koshi-2013 population. Nevertheless, in antixenosis tests, Koshi-2013 settled less on all NILs than on Sagabiyori. In addition, adult mortality and the percentage of fresh weight loss of lines carrying BPH17 and BPH3 indicated that these lines have higher resistance to Koshi-2013 than Sagabiyori. Current study revealed that BPH resistance of Sagabiyori became stronger by transferring BPH3 and BPH17 genes. Thus, BPH3 and BPH17 might be valuable for breeding programs to enhance BPH resistance of high grain quality rice varieties with heat tolerance.

A Study on Bio-efficacy of Dinotefuran 20% SG against Brown Plant Hopper Nilaparvatha lugens (Stall) on Paddy Oryza sativa L

In rice cultivation, the Brown plant hopper causes damage to growth of plants by sucking cell sap and it causes in drying of plants and crop fields this effects on plant growth and turns into yellow color later brown. In order to overcome this kind of damage particularly in rice cultivation, a field trial was conducted during kharif 2017 at Agricul Research Station Gangavathi to the assess the bio-efficacy of Dinotefuran 20% SG against brown plant hopper Nilaparvatha lugens (Stall) on paddy. The results revealed that, the new insecticide Dinotefuran 20% SG 40 g a.i./ha showed lowest population of 0.86 and 0.73, 0.67 and 0.57 BPH/hill at 3, 7,10 and 15 days after spray (DAS) respectively and this treatment was significantly superior over rest of the treatments. Further, it was on par with lower dose of Dinotefuran 20% SG @ 30 g a.i./ha which is recorded 1.63, 1.60, 1.49 and 1.42 BPH/hill at 3, 7, 10 days and 15 DAS respectively, followed by standard check buprofezin @187.5g a.i./ha recorded 1.63, 1.90, 2.05and 2.15 and BPH/hill at 3, 7,10 and 15 DAS respectively. Another insecticide imidacloprid @ 22.5g a.i./ ha was found inferior to all other treatments by harbouring4.43,4.53, 4.76 and 4.87 BPH/hill, where as the untreated control recorded highest BPH population of 21.70 to 25.64 BPH/hill through out the observational period from one day before to 15 DAS respectively. The maximum additional yield was 22.37% was recorded over control (64.28 q/ha) was found in case of Treatment 4 (T4) with an incremental benefit cost ratio of 3.72.

The brown planthopper (Nilaparvata lugens) attack and its genetic diversity on rice in Bali, Indonesia

Abstract. Listihani L, Ariati PEP, Yuniti IGAD, Selangga DGW. 2022. The brown planthopper (Nilaparvata lugens) attack and its genetic diversity on rice in Bali, Indonesia. Biodiversitas 23: 4696-4704. The brown planthopper (Nilaparvata lugens) is an important pest on rice crops in Indonesia. The genetic diversity of BPH isolates in western Indonesia has been extensively reported, whereas eastern Indonesia isolates have not been reported. This research aims to analyze genetic diversity and evaluate the BPH attack's intensity on Bali rice plants. The research method used was an observation of attack percentage, population dynamics, attack intensity, and genetic diversity of BPH in 9 districts in Bali (Badung, Gianyar, Klungkung, Bangli, Karangasem, Tabanan, Denpasar City, Buleleng, and Jembrana). Molecular identification was carried out on N. lugens DNA in the mtCOI fragment. BPH attacks of >50% were found in the districts of Gianyar, Bangli, Jembrana, and Badung. The BPH population was primarily found in Ciherang and IR-64 varieties of rice in the Badung Regency, with 43.67 BPH per rice hill. In general, rice varieties grown in all observation locations were susceptible to BPH, such as Ciherang, IR-64, Inpari 32, and Situbagendit. In the Ciherang and IR-64 varieties, the highest attack intensity average value reached 30%. The sequence of N. lugens isolate from Bali Jembrana showed the highest nucleotide and amino acid homology with N. lugens isolate FSD-034 from Pakistan (MK301229) biotype Y of 99.5 -99.74% and 100%, respectively. This study found N. lugens biotype Y in rice plants for the first time in Indonesia. This study reported that Rice varieties Situbagendit and Inpari 32, previously resistant to BPH, are reported as susceptible to BPH.

Identification of novel candidate of brown planthopper resistance gene Bph44 in rice (Oryza sativa L.)

The brown planthopper (BPH, Nilaparvata lugens Stål) is still considered a major threat to ricefarmers. Exploring novel resistance genes that relate to the BPH population in the targeted rice-growing area might be a suitable solution. We identified and mapped the gene locususing 175 lines of F2:3 populations derived from Balamawee×PD601. Genomic analysis was then used to identify the candidate gene governing the resistance toward BPH. We discovered a novel genetic locus for BPH resistance in the long arm of chromosome 4 linked to markers Q31 and RM17007 at 4.76 and 5.42 cM, respectively, with total phenotypic variation reaching 52.21% at LOD 29.68. The tolerance mechanism influences the nature of this resistance, as shown by the Functional Plant Loss Index. The resistance level, mechanism of resistance, and physical mapping reveal that the resistance genes in this study differ from the previous study, therefore, we propose this novel gene as Bph44.

Assessment of IPM module on brown planthopper incidence in rice crop

The experiment was carried out in 4.0 ha with active participation of farmers with an objective to assess the integrated management module for the management of brown planthopper in rice for three years. Maximum temperature, morning relative humidity, rainfall and evening relative humidity favours BPH population. Minimum temperature impacted the BPH. The mean incidence of BPH population/hill was lower in IPM module (2.97 and 12.03 at tillering and panicle initiation stage respectively) as compared to farmers practice (13.34 and 30.62 at tillering and panicle initiation stage respectively). The mean yield of IPM module was 70.7 q/ha with net returns and C:B ratio of Rs. 62604/ha and 1:2.15, respectively. Whereas, farmer's practice recorded a mean yield of 61.5 q/ha with net returns and C:B ratio of Rs. 48357/ha and 1:1.89, respectively. The increase in yield over farmer's practice was 14.9%.

Predation of Phidippus sp [Araneae: Salticidae] on Nilaparvata lugens [Hemiptera: Delphacidae] at different densities

Phidippus sp. (Araneae: Salticidae) is often found in rice field and has potency as the natural enemy of Nilaparvata lugens (Hemiptera: Delphacidae). The study aimed to know the predation of Phidippus sp on N. lugens in laboratory. The study used a Completely Randomized Design consisting of five treatments and five replications. The treatments were the difference of N. lugens densities of 10, 20, 30, 40, and 50. Phidippus sp was collected from rice fields around Padang City, while N. lugens used was 2nd-3rd instar of nymphs reared in laboratory. The results showed that Phidippus sp has potency for controlling the BPH population. The predation tended to increase with increasing N. lugens density, but the percentage of predation and weight gain decreased. Phidippus sp was able to consume prey provided to a maximum of 96.0%. The increasing density shortened the time needed by Phidippus sp to find prey. The shortest time to find the first prey and the highest number of predation occurred at 50 individuals of N.lugens provided (1.99 minutes for 28.2 individuals preyed) but in lowest percentage of predation and weight gain (56.4% and 0.0004 g/day respectively). The functional response of Phidippus sp was logarithmic with a weak to strong correlation (r = 0.515).

Incidence of Major Insect Pests and Natural Enemies in Three Rice Growing Seasons of Bangladesh

Incidence of insect pests and their associated natural enemies was investigated from July 2017- June 2018 at six locations (Gazipur, Rajshahi, Barishal, Sonagazi, Rangpur, Cumilla) of Bangladesh to identify their major occurrence period as well as their incidence in three rice growing seasons, (Aus, T. Aman, and Boro). Among the tested locations, marked differences were found in the composition of insect pest and natural enemies. Higher number of pest population was found at Gazipur with 80,000 individuals for insect pest and 40,000 individuals for natural enemies. At least one peak for major insect pest and natural enemies suggested their specific occurrence period across the locations. Among the insect pests, major peak of GLH was found at Gazipur and Rajshahi during T. Aman season with 4,000 individuals for each location. In contrast, BPH population was as high as 10,000 individuals for Gazipur in October during T. Aman season. Additionally, it was high at Rajshahi in October and November with around 2,000 individuals of BPH. For WBPH, one major peak was found in October at Gazipur and Rajshahi with 10,000 and 2,000 individuals respectively. For YSB, it was higher at Rajshahi in October with over 6,000 individuals during T. Aman season. Moreover, one major peak also observed in Barishal with over 2,000 individuals in November. Among natural enemies, CDB population was observed mainly at three locations in between October and November with 900 individuals for Gazipur, 400 individuals for Rajshahi and 200 individuals for Barishal during T. Aman season. In contrast, for STPD population, two major peaks were found in Barishal with 6,000 and 5,000 individuals in December and March respectively during Boro season. For GMB population, it was observed at Gazipur in November with more than 20,000 individuals during T. Aman season whereas Rajshahi had around 2,000 individuals in the same month. However, higher incidence of GLH, BPH, and WBPH at Gazipur and Rajshahi suggested availability of insect pests during T. Aman season. In contrast, higher YSB incidence at Barishal and Rajshahi indicated their abundance in those areas. On the other hand, incidence of natural enemies at Gazipur indicated presence of greater biological control compared with other locations. In future, this information could serve as a reliable source in strengthening rice pest monitoring services as well as effective pest control in Bangladesh.
 Bangladesh Rice j. 2019, 23(1): 35-43

Predicting Rice Pest Population Occurrence with Satellite-Derived Crop Phenology, Ground Meteorological Observation, and Machine Learning: A Case Study for the Central Plain of Thailand

The brown planthopper Nilaparvata lugens (BPH) is one of the most harmful insect pests in rice paddy fields, which causes considerable yield loss and consequent economic problems, particularly in the central plain of Thailand. Accurate and timely forecasting of pest population incidence would support farmers in planning effective mitigation. In this study, artificial neural network (ANN), random forest (RF) and classic linear multiple regression (MLR) analyses were applied and compared to forecast the BPH population using weather and host-plant phenology factors during the crop dry season from 2006 to 2016 in the central plain of Thailand. Data from satellite earth observation was used to monitor crop phenology factors affecting BPH population density. An ANN model with integrated ground-based meteorological variables and satellite-derived host plant variables was more accurate for short-term forecasting of the peak abundance of BPH when compared with RF and MLR, according to a reasonably validating dataset (RMSE of natural log-transformed (ln) BPH light trap catches = 1.686, 1.737, and 2.015, respectively). This finding indicates that the utilization of ground meteorological observations, satellite-derived NDVI time series, and ANN have the potential to predict BPH population density in support of integrated pest management programs. We expect the results from this study can be applied in conjunction with the satellite-based rice monitoring system developed by the Geo-Informatic and Space Technology Development Agency of Thailand (GISTDA; http://rice.gistda.or.th) to support an effective pest early warning system.

Analisis pengaruh faktor cuaca terhadap dinamika populasi wereng batang coklat (Nilaparvata lugens Stål) yang tertangkap lampu perangkap

Wereng batang coklat (WBC) merupakan salah satu hama utama tanaman padi yang serangannya menyebabkan penurunan produksi padi. Kelimpahan populasi WBC di pertanaman padi dipengaruhi oleh faktor cuaca. Indikasi awal kelimpahan populasi WBC di pertanaman dapat dilihat dari jumlah WBC yang tertangkap lampu perangkap. Penelitian ini bertujuan melakukan analisis pengaruh faktor cuaca terhadap dinamika populasi Nilaparvata lugens Stål (wereng batang coklat). Metode analisis yang digunakan untuk melihat pengaruh masing-masing faktor cuaca terhadap dinamika populasi WBC adalah analisis korelasi dan regresi linier berganda. Masalah multikolinearitas antar faktor cuaca yang berpengaruh dianalisis menggunakan metode regresi komponen utama. Curah hujan, kelembaban minimum, dan hari hujan memiliki korelasi kuat terhadap dinamika populasi WBC. Hasil uji subset antara ketiga faktor tersebut menghasilkan pasangan faktor yang terbaik, yaitu hari hujan dan kelembaban minimum. Persamaan regresi antara faktor hari hujan dan kelembaban minimum terhadap populasi WBC cukup baik dalam menggambarkan peningkatan populasi WBC yang seiring dengan peningkatan jumlah hari hujan pada kondisi kelembaban minimum yang fluktuatif di pertanaman.

Jinggangmycin-Induced UDP-Glycosyltransferase 1-2-Like Is a Positive Modulator of Fecundity and Population Growth in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae).

The antibiotic jinggangmycin (JGM) is broadly applied in Chinese rice producing regions to control rice blight, a fungal disease. Aside from protecting rice plants from the disease, JGM leads to the unexpected action of stimulating brown planthopper (BPH; Nilaparvata lugens; Hemiptera: Delphacidae) reproduction to the extent it can influence population sizes. The JGM-induced BPH population growth has potential for severe agricultural problems and we are working to understand and mitigate the mechanisms of the enhanced reproduction. UDP-glucuronosyltransferases (UGTs) are multifunctional detoxification enzymes responsible for biotransformation of diverse lipophilic compounds. The biological significance of this enzyme family in insect fecundity is not fully understood, however, upregulated UGT12 in JGM-treated BPH, may influence fecundity through metabolism of developmental hormones. This idea prompted our hypothesis that NlUGT12 is a positive modulator of BPH reproductive biology. JGM treatment led to significant increases in accumulations of mRNA encoding NlUGT12, numbers of eggs laid, oviposition period, juvenile hormone III titers, and fat body, and ovarian protein contents. dsUGT12 treatment suppressed NlUGT12 expression and reversed JGM-enhanced effects, resulting in under-developed ovaries and reduced expression of juvenile hormone acid methyltransferase and the JH receptor, methoprene tolerant. Application of the JH analog, methoprene, on dsUGT12 treated-females partially reversed the dsUTG12 influence on vitellogenin synthesis and on NlUGT12 expression. These results represent an important support for our hypothesis.

High-resolution mapping and breeding application of a novel brown planthopper resistance gene derived from wild rice (Oryza. rufipogon Griff)

BackgroundThe brown planthopper (Nilaparvata lugens Stål; BPH), one of the most destructive pests of rice, has proven to be a substantial threat, conferring enormous production losses in Asia and becoming a difficult challenge to manipulate and control under field conditions. The continuous use of insecticides promotes the resurgence of BPH, which results in resistant varieties adapting through the upgrading of new BPH biotypes. To overcome resistance acquired by BPH against resistance varieties, different forms of novel resistant gene fusions act as functional domains for breeding to enhance insect resistance.ResultsThe current study reports on the novel BPH resistance gene Bph36 derived from two introgression lines (RBPH16 and RBPH17) developed from wild rice GX2183 which was previously reported to be resistant to BPH. Using two F2 crossing populations (Kangwenqizhan × RBPH16 and Huanghuazhan × RBPH17) in a bulked segregant analysis (BSA) for identification of resistant genes and QTL analysis, two QTLs for BPH resistance were generated on the long and short arms of chromosome 4, which was further confirmed by developing BC1F2:3 populations by backcrossing via marker assisted selection (MAS) approach. One BPH resistance locus on the short arm of chromosome 4 was mapped to a 38-kb interval flanked by InDel markers S13 and X48, and then was named Bph36, whereas another locus on the long arm of chromosome 4 was also detected in an interval flanked by RM16766 and RM17033, which was the same as that of Bph27. An evaluation analysis based on four parameters (BPH host selection, honeydew weight, BPH survival rate and BPH population growth rate) shows that Bph36 conferred high levels antibiosis and antixenosis to BPH. Moreover, Bph36 pyramided with Bph3, Bph27, and Bph29 through MAS into elite cultivars 9311 and MH511 (harbored Xa23), creating different background breeding lines that also exhibited strong resistance to BPH in the seedling or tillering stage.ConclusionBph36 can be utilized in BPH resistance breeding programs to develop high resistant rice lines and the high-resolution fine mapping will facilitate further map-based cloning and marker-assisted gene pyramiding of resistant gene. MAS exploited to pyramid with Bph3, Bph27, Bph29, and Xa23 was confirmed the effectiveness for BPH resistance breeding in rice and provided insights into the molecular mechanism of defense to control this devastating insect.

Fluktuasi Populasi Serangga Wereng Batang Coklat (Nilaparvata lugens) Pada Lahan Sawah Di Kabupaten Kerawang Jawa Barat

Brown Planthopper (Nilaparvata lugens Stal.) is a main pest of paddy. The purpose of this research is to study the population of Brown Planthopper and the natural enemy. The method of this research using survey. Survey was conducted in three experimental plots at JatisariSubdistrict, Karawang District, West Javaand in the greenhouse of the Department of Plant Pests and Deseases, Faculty of Agriculture, Universitas Padjadjaran. The sample were collected by systematically diagonal using yellow stiky trap and manually or visual counting. The result showed population fluctuation BPH below the economy line where is temperature, humidity and rainfall did not significantly effect to the BPH population. It was indicated by the regression analysis of each temperature Y= (- 24.225 + 1.008 X1 ; R2 =0,020; P/Sign = 0.660), Humidity (Y=- 32.337 + 0.424 X2; R2 = 0,124; P/ Sign = 0.261) and Rainfall (Y=1.707 + 0.090 X3 ; R2 = 0.050; P/ Sign = 0.487). There is a relation between temperature, humidity and rainfall to BPH (Y = - 123 + 2.685 T + 0.649 RH - 0.14 CH; R2 = 0.236; P/ Sign = 0.516) dit not significantly because as the value of significance (P = Sign) > 0.05.8. The diversity index was moderate 1.88

Evaluation of new insecticides against rice brown plant hopper

Evaluation of six insecticides viz., ethiprole 40 + imidacloprid 40 WG, etofenprox 10 EC, buprofezin 25 SC, pymetrozine 50 WG, acephate 75 SP and monocrotophos 36 SL were evaluated against rice brown plant hopper BPH. The BPH population was counted on 20 randomly selected hills before spray at 1, 3, 7 and 10 days after spray. The experiment was conducted during kharif 2014 and 2015 at the Agricultural Research Station, Kampasagar, laid out in Randomized Block Design with three replications. All the insecticides significantly reduced the BPH. The BPH population varied from 114.0 to 156.6 and 133.4 to 176.6/20 hills during kharif 2014 and 2015 at one day prior to spray. The population was significantly lower with pymetrozine 50 WG @ 250 g/ha, followed by ethiprole 40 + imidacloprid 40 W.G @ 125 g/ha, etofenprox 10 EC @ 750 ml/ha, acephate 75 SP @ 667g/ha, monocrotophos 36 SL @ 1390 ml/ha and buprofezin 25 SC @ 825 ml/ha at all the counting days of after spray in both 2014 and 2015. The maximum reduction of population was found with pymetrozine 50 WG. The highest grain yield was obtained with pymetrozine 50 WG @ 250 g/ha in kharif 2014 and 2015.

Regional population differences of the brown planthopper (Nilaparvata lugens Stål) in Cambodia using genotyping-by-sequencing.

The brown planthopper Nilaparvata lugens Stål (BPH) can be found year-round in tropical region and causes severe damage to rice. Although there has been documented BPH damage to rice crops in the past decade in Cambodia, the extent of this epidemic is poorly understood. Here, we examined the time variation of BPH population in the abundance of morphotypes in 13 main rice-producing provinces (86 sites) by aspirator method and in the Takeo Province (five sites) by yellow sticky trap method. At least three generations were observed during the 3-month collection period in the rainy growing season. Regarding the occurrence of BPH morphotypes, in July the macropterous adults were restricted to south Cambodia and in August all morphotypes, adults (macropterous and brachypterous) and nymphs, appeared in all sampling sites. To explain the difference of regional distribution, the genetic differentiation was analyzed in south and northwest Cambodia (three sites) by using single nucleotide polymorphisms (SNP) analysis via genotyping-by-sequencing (GBS) using next-generation sequencing. The 2455 SNPs obtained by GBS clarified the three sub-populations and they corresponded to the expected dissemination patterns. These results provide a clue to understand the differentiation and epidemic of BPH in Cambodia.

PHF7, a novel male gene influences female fecundity and population growth in Nilaparvata lugens St\xe5l (Hemiptera: Delphacidae)

PHF7 exhibits male-specific expression in early germ cells, germline stem cells and spermatogonia in insects, and its expression promotes spermatogenesis in germ cells when they are present in a male soma. However, the influence of male-specific PHF7 on female reproductive biology via mating remains unclear. Thus, we investigated the potential impacts of male PHF7, existed in seminal fluid of Nilaparvata lugens (NlPHF7), on fecundity and population growth via mating. Our results revealed that suppressing male NlPHF7 expression by RNAi led to decreases in body weight, soluble accessory gland protein content, arginine content, and reproductive organ development in males, resulting in significant reduction of oviposition periods and fecundity in females, and significant decrease in body weight, fat body and ovarian protein content, yeast-like symbionts abundance, ovarian development and vitellogenin gene expression in their female mating partners. Similarly, suppression of NlPHF7 expression in males mated with the control female reduced population growth and egg hatching rate, but did not influence gender ratio. We infer that NlPHF7 play a role important in stimulating female fecundity via mating. This study provides valuable information by identifying a potentially effective target gene for managing BPH population through RNAi.

Influence of Climate Variability on Brown Planthopper Population Dynamics and Development Time

Brown planthopper or Nilaparvata lugens (BPH) is one of the rice major pest in Indonesia. BPH can cause extensive damage and almost always appear in each planting season, frequent explosions attack (outbreaks) resulting in very high economic losses. Outbreaks of BPH were often occurred in paddy fields in Indramayu regency and several endemic regency in Java island, where rice is cultivated twice to three times a year both in the rainy and dry cropping seasons. The output of simulation shows the BPH population starts increasing from December to February (rainy season) and from June to August (dry season). The result relatively had same pattern with light trap observation data, but overestimate to predict BPH population. Therefore, the output of simulation had adequately close pattern if it is compares to BPH attacked area observation data. The development time taken by different stages of BPH varied at different temperatures. BPH development time at eggs and adults stage from the simulation output is suitable with BPH real lifestage, but at nymphs stage the result is different with the concept of development time.