Field evolution of insecticide resistance in the brown planthopper (Nilaparvata lugens Stål) in China

The brown planthopper (Nilaparvata lugens Stål) is one of the most destructive pests of rice crops in Asian countries including China, Vietnam, Thailand, etc. Evolution of resistance in this pest insect to isoprocarb, buprofezin, pymetrozine, imidacloprid and other neonicotinoid insecticides has been reported. In order to investigate the current status of resistance to commonly used insecticides, nine field populations of N. lugens were collected from Central China, East China and South China, and resistance to insecticides was monitored from 2009 to 2012. All the 9 field populations collected in 2012 had developed extremely high resistance to imidacloprid, with resistance ratios (RR) ranging from 209.3 to 616.6. Resistance to imidacloprid was much higher in 2012 than in 2009. The RR of thiamethoxam varied from 17.4 to 47.1, and the RR of nitenpyram varied from 1.4 to 3.7 in 2012. Of the 9 field populations, six populations showed higher resistance to nitenpyram in 2012 than in 2011. RR for buprofezin varied from 110.1 to 221.6 in 2012 whereas resistance was at a medium level (RR 20.4 ∼ 39.4-fold) in 2009. RR for pymetrozine ranged from 34.9 to 46.8 in 2012. As for isoprocarb, RR ranged from 21.7 to 38.1 in 2012. The obvious increase in resistance to widely applied insecticides indicates that insecticide resistance management strategies are urgently needed to prevent or delay further increase of insecticide resistance in N. lugens.     

Resistance of Oryza minuta to Nilaparvata lugens (Stl)

Evaluation of O. minuta for the re-sistanee to the brown planthopper(BPH), Nilaparvata lugens (Stal)was carried out by using ModifiedSeedbox Screening Technique(MSST). Based on the significantdifferences between O. minuta,E13-9, and the susceptible checkvariety, TN1, the resistance of O.minuta to BPH was determined byusing a series of resistance indices     

Bacterial Community in Different Populations of Rice Brown Planthopper Nilaparvata lugens(Stl)

The structures of bacterial communities in the brown planthopper (BPH) Nilaparvata lugens (Stål) from different geographic and resistant virulent populations were analyzed by using denatured gradient gel electrophoresis (DGGE). Results showed that the bacterial communities in BPH nymph from the first to the fifth instars varied with nymphal growth and development. The bacterial communities in the first-instar BPH nymph were similar to those in adults. Nine geographic BPH populations were divided into three groups based on the cluster analysis of DGGE fingerprint. The first group was from the Philippines; the second group was from Thailand and Hainan, Yunnan and Zhejiang provinces of China; and the third group was from Vietnam and Guangxi, Hunan and Jiangxi provinces of China. BPH populations adapted to different resistant rice varieties. The BPH populations from Mudgo (with resistant gene Bph1) and ASD7 (with resistant gene bph2) differed with those of the susceptible rice variety TN1.     

Identification and Function Analysis of enolase Gene NlEno1 from Nilaparvata lugens (St?l) (Hemiptera:Delphacidae)

The enolase [EC 4.2.1.11] is an essential enzyme in the glycolytic pathway catalyzing the conversion of 2-phosphoglycerate (2-PGE) to phosphoenolpyruvate (PEP). In this study, a full-length cDNA encoding α-enolase was cloned from rice brown planthopper (Nilaparvata lugens) and is provisionally designated as NlEno1. The cDNA sequence of NlEno1 was 1,851 bp with an open reading frame (ORF) of 1,305 bp and encoding 434 amino acids. The deduced protein shares high identity of 80–87% with ENO1-like protein from Hemiptera, Diptera, and Lepidoptera speices. The NlEno1 showed the highest mRNA expression level in hemolymph, followed by fat body, salivary gland, ovaries and egg, and showed trace mRNA levels in testis. The mRNA of NlEno1 showed up-regulated level in virulent N. lugens population Mudgo, IR56 and IR42 when compared with TN1 population. Injection of double-stranded RNA (dsRNA) of NlEno1 into the adults significantly down-regulated the NlEno1 mRNA level along with decreased eggs and offspring. Moreover, injection of NlEno1-dsRNA decreased mRNA level of Vitellogenin (Vg) gene. These results showed that the NlEno1, as a key glycolytic enzyme, may play roles in regulation of fecundity and adaptation of N. lugens to resistant rice varieties.     

Genetic Analysis and Preliminary Mapping of Two Recessive Resistance Genes to Brown Planthopper, Nilaparvata lugens Stl in Rice

An F2 population derived from the cross of WB01, an introgression line resistant to brown planthopper (BPH) originated from Oryza rufipogon Griff. and a susceptible indica variety 9311, was developed for genetic analysis and gene mapping. The population with 303 F2:3 families was genotyped by 141 simple sequence repeat (SSR) markers and used for gene mapping. Two softwares, Mapmaker/Exp 3.0 and Windows QTL Cartographer V2.0 were applied to detect QTLs. Totally, two QTLs resistant to BPH, named temporarily a...     

Genetic Analysis and Preliminary Mapping of Two Recessive Resistance Genes to Brown Planthopper,Nilaparvata lugens Stl in Rice

An F2 population derived from the cross of WB01, an introgression line resistant to brown planthopper (BPH) originated from Oryza rufipogon Griff. and a susceptible indica variety 9311, was developed for genetic analysis and gene mapping. The population with 303 F2:3 families was genotyped by 141 simple sequence repeat (SSR) markers and used for gene mapping. Two softwares, Mapmaker/Exp 3.0 and Windows QTL Cartographer V2.0 were applied to detect QTLs. Totally, two QTLs resistant to BPH, named temporarily a...     

Effects of the insecticide triazophos on the ultrastructure of the flight muscle of the brown planthopper Nilaparvata lugens Stål (Hemiptera: Delphacidae)

The brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), is a long-distance migratory insect pest in temperate eastern Asia and is a classical resurgent rice pest that is induced by insecticides. Knowledge of the effect of insecticides on the flight capacity of insects is needed to understand their migration, which may help to improve the management of insect pests. Our previous study demonstrated that some insecticides enhance the flight capacity of BPH. However, the effect of insecticides on the flight muscle of BPH is not well understood. Thus, the present study examined the effect of triazophos, a classical insecticide that induces the resurgence of BPH, on the ultrastructure of macropterous females using transmission electron microscopy. The results showed that the diameter of myofibrils one and two days after adult female emergence (DAE) following treatment with 40 ppm triazophos was significantly greater than that of the control, increasing by 31.4 and 21.5%, respectively. In addition, the length of the sarcomeres at two and three DAE was significantly greater than that of the control, increasing by 73.8 and 50.8%, respectively. The percentage of mitochondrial volume in the muscle fibres at one and two DAE was 146.2 and 67.7% greater than that of the control, respectively. These findings show that the mechanisms of triazophos-induced enhancement of the flight capacity of BPH involve changes in the ultrastructure of the flight muscle.     

Greenhouse techniques to identify field resistance to the brown planthopper,Nilaparvata lugens (Stål) (Homoptera: Delphacidae), in rice cultivars

Two seedbox screening techniques were compared to determine levels of resistance of rice cultivars to three brown planthopper, Nilaparvata lugens (Stål), biotypes. The commonly used standard seedbox screening test (SSST) where eight second-instar nymphs were infested on 7-day-old seedlings was compared with a modification (MSST) where four second-instar nymphs were infested on each of 20-day-old plants. In the SSST, the initial infestation killed the susceptible cultivars whereas in the MSST the F₁ progeny killed the susceptible cultivars. The cultivars ASD 11, Wagwag, Utri Rajapan, IR46 and Kencana were susceptible in the SSST but moderately resistant or resistant in the MSST, indicating an increase in the level of resistance with plant age. Feeding rate and population growth of N. lugens were the factors involved in the resistance of 30-day-old plants. The MSST provides a rapid method for identifying field-resistant cultivars in the greenhouse and can be used to identify field-resistant lines in a rice-breeding programme for stable resistance to N. lugens.     

High Temperature Modifies Resistance Performances of Rice Varieties to Brown Planthopper,Nilaparvata lugens(Stl)

To investigate the effect of temperature on the resistance characteristics of rice varieties with different resistance genes to brown planthopper(BPH),Nilaparvata lugens(Stl),the resistances of IR26(Bph1)and IR36(bph2)to BPH population in Hangzhou,China were monitored in greenhouse during September in 2007 and 2008 by using the standard seedling screening techniques(SSST)developed by the International Rice Research Institute(IRRI).Furthermore,the changes in resistance of IR26 and IR36 to BPH,soluble sugar and oxalic acid contents in 25-day-old rice plants of susceptible variety TN1 and resistant varieties IR26 and IR36 were detected at five temperatures(22℃,25℃,28℃,31℃ and 34℃).IR26 completely lost resistance both in greenhouse and at the five tested temperatures.IR36 still had moderate resistance at natural temperature,but its resistance decreased gradually when the temperature increased from 25℃ to 34℃,and fully lost its resistance at 31℃ and 34℃.The highest durable resistance of IR26 and IR36 were recorded at 25℃.The soluble sugar content in plants of the three tested rice varieties increased with temperature increase,and the oxalic acid content increased with the temperature increase at first,maximized at 25℃,and then declined.Two-way ANOVA indicated significant effects of temperature and rice variety on contents of soluble sugar and oxalic acid in rice plants.     

Donors for Resistance to Brown Planthopper Nilaparvata lugens(St?l) 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(St?l) 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.     

Susceptibility to Insecticides and Ecological Fitness in Resistant Rice Varieties of Field Nilaparvata lugens Stl Population Free from Insecticides in Laboratory

A population of rice brown planthopper(BPH) Nilaparvata lugens collected from a paddy field in Hangzhou was successively reared on susceptible rice Taichung Native 1(TN1) in a laboratory free from insecticides for more than 14 generations. The changes in susceptibility to insecticides and ecological fitness on different resistant rice varieties were monitored in each generation. The resistance ratio to imidacloprid sharply declined with the succession of rearing generations without insecticides from 359.94-fold at F1 to 6.50-fold at F14 compared with the susceptible strain, and the resistance ratio to chlorpyrifos was from 9.90-fold at F1 to 5.94-fold at F14. Nymphal duration and weights of newly hatched female adults were significantly affected by rice variety, generation and their interactions, but nymphal survival was significantly affected by the generation only. The ratio of brachypterous adults in males was affected by the generation and generation × variety interaction, whereas no difference was found in females. Nymphal duration extended with increasing generations, and the female nymphal duration was shorter in the susceptible variety TN1 than those in the resistant varieties IR26 and IR36. In addition, the female adult weight in TN1 was higher than those in IR26 and IR36. These results indicated that the resistance of field BPH population to insecticides was reversed after several generations of no-exposure to insecticides, and the ecological fitness in TN1 was higher than those in IR26 and IR36. These findings suggested the rational and reduced use of insecticides in combination with the manipulation of resistant rice varieties would be effective for BPH management.     

Changes in Methamidophos Resistance and Fitness of Hybrids in Different Strains of Nilaparvata lugens

A resistant strain selected successively in the laboratory for 17 generations had 198.63-fold resistance to methamidophos. The resistant levels and fitness of progenies from the resistant strain and susceptible strain or field population were closer to those of the resistant strain than those of the susceptible strain or field population. The changes in the resistant levels of the hybrid were propitious to the resistance development, however, the changes of the fitness went to the contrary. The effects of the migration on the development of methamidophos resistance in Nilaparvata lugens were discussed in the aspects of the migration of Nilaparvata lugens, the resistant levels of progenies and the changes of the fitness.     

A method for raising brown planthopper (BPH), Nila-parvata lugens (Stl)

To get mass ppoulation of the BPH, agood method for rasing BPH isneeded. In this paper, a convenientmethod was recommended.BPH population used in the ex-periment was provided by Jiangsu A-cad of Agri Sci. Six raising BPHmethods, i. e, with rice buds (RB),rice seedling (RS), seedling soillesscultured (SSC), mature rice (MR),and rice stem cultured in nutrient     

Relationship between biological features and the SMVS''''s inhibitory effect on mating behavior of Nilaparvata lugens (Stal)

Our previous studies revealed that second malevibration signal (SMVS) restrained the matingbehavior of N. lugens, the influences of threebiological features (density, age, and wingform) on SMVS's inhibitory effect were hereinstudied by playing back its record. The dura-tion of playback was 4 h. Except otherwisestatement, N. lugens tested were virginmacropterous males and females aged 4-6 d af-ter emergence, and the density was 5 pairs (5females and 5 males) of N. lugens per cage (4cm in diameter and 8 cm in height). The in-hibitory effect of SMVS was evaluated usingmating rate (i. e. the rate of females withspermatophore). The results were as follows:     

Effects of endosymbiote on feeding, development, and reproduction or brown plan-thopper, Nilaparvata lugens stl

The biotype 1, 2, and 3 of N. lugens obtained from IRRI, the Philippines,were reed continuously on suscepti-ble variety TN1, resistant varieties Mudgo (Bph1), and ASD7 (Bph2),respectively. To eliminate theyeast-like symbionts (YLS) inN. lugens, about 60-d old plants ofTN1 beating 3-d old ears were laid at26℃ for 2d and exposed at 35℃ inan incubator for 3 d. After a hottreatment, the plants were transferred into an incubator at 26℃ for eggdevelopment. The hatched aposymbi-otic nymphs…     

Injury to apples and peaches at harvest from feeding by Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) nymphs early and late in the season

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive species that has become an important orchard pest in the Mid-Atlantic region of the US. Adults and nymphs feed on tree fruit. Feeding injury from adults has been characterized but the injury from nymphs has not been examined systematically. Since the four plant-feeding instars of H. halys (second through fifth) differ substantially in size, it is plausible that the effects of their feeding on fruit injury and injury expression may differ among them. We compared feeding injury at harvest from young nymphs (second plus third instars), older nymphs (fourth plus fifth instars), and adults that were caged on ‘Smoothee Golden’ apples and ‘Redhaven’ peaches in early June (peach and apple), late July (peach), and late August (apple). Individual apples and peaches were caged at fruit set and assigned to the following treatments (n = 28/treatment): 1) control (no H. halys), 2) young nymphs or 3) adults early in the season, and 4) young nymphs, 5) older nymphs or 6) adults later in the season. Fruit in each treatment were exposed to 3–4 young nymphs, two older nymphs or 1–2 adults placed in the cages for 96 h and evaluated for external and internal feeding injury within 36 h after harvest. No injury was recorded from unexposed peaches or apples. The percentage of injured fruit and number of injuries per fruit varied significantly among the exposed treatments. Early season feeding by young nymphs yielded the least injury to peaches and apples. In apples, the highest percentage of injured fruit and number of injuries per fruit were caused by late season feeding by adults. In peaches, early season adult feeding produced the highest percentage of injured fruit and injuries per fruit. More internal than external injury was recorded on peach and no such difference was observed on apple. The implications of these findings on H. halys management in fruit orchards are discussed.