Aspects of brown planthopper adaptation to resistant rice varieties with the Bph3 gene

Despite over 30 years of deployment, varieties with the Bph3 gene for resistance to the brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), are still effective in much of the Philippines. In the present study, we determined the effects of adaptation to one resistant variety, IR62 – assumed to possess the Bph3 gene – on (1) resistance against a series of varieties with similar biotypical responses (presumed to contain the same major resistance genes), and (2) a differential variety with the bph4 gene that occurs at the same chromosome position as Bph3. We also examined the effects of high soil nitrogen on the effectiveness of Bph3. Feeding, planthopper biomass, and development times were reduced in a wild BPH population when reared on IR62 compared with the susceptible standard variety TN1. However, nitrogen application increased the susceptibility of IR62. After 13 generations on IR62, BPH had adapted to the plant’s resistance. Virulence of the adapted BPH against the variety ‘Rathu Heenati’ supports the idea that Bph3 is present in IR62. Across similar IR varieties (IR60, IR66, IR68, IR70, IR72, and IR74), feeding, planthopper biomass, and development rates were generally higher for IR62‐adapted than for non‐adapted BPH; however, contrary to expectations, many of these varieties were already susceptible to wild BPH. Fitness was also higher for IR62‐adapted BPH on the variety ‘Babawee’ indicating a close relation between Bph3 and bph4. The results indicate that the conventional understanding of the genetics behind resistance in IR varieties needs to be readdressed to develop and improve deployment strategies for resistance management.     

Identification of antibiosis and tolerance in rice varieties carrying brown planthopper resistance genes

Brown planthopper (BPH) [Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)] is a major pest in rice [Oryza sativa L. (Poaceae)] production. Identification of resistance genes and development of BPH‐resistant varieties is an economical and effective way to control this pest. In this study, BPH honeydew excretion, survival rate, and emergence rate were used as indicators to detect the antibiotic level, whereas the relative growth rates of plant height (R_H) and fresh weight (R_W), and the number of days until yellowing were used to identify the level of tolerance to BPH in rice varieties. Rice varieties Swarnalata and B5, which showed high levels of antibiosis and tolerance to BPH, thus were highly resistant in the seedling bulk test; Mudgo and T12, which showed moderate resistance to the insects, had a high level of tolerance and moderate antibiosis to BPH. Varieties Rathu Heenati, ARC 10550, and Chin Saba were identified to be susceptible to BPH, showing a moderate level of tolerance and no antibiosis. In comparison to the evaluation methods of BPH resistance, the honeydew excretion and survival rate could be used to detect the antibiotic level, and the R_H, R_W, or leaf yellowing days could be employed as indicators to evaluate the rice varieties’ tolerance. Overall, a combined application of these indicators can effectively identify the levels of antibiosis and tolerance to BPH in rice varieties, and BPH‐resistance levels of the varieties were mainly determined by the antibiosis level. The results should help in understanding BPH‐resistance categories of rice varieties and for resistance breeding.     

十六个水稻品种(系)对褐飞虱的抗虫性评价

本文通过苗期抗性鉴定、田间抗虫性鉴定、稻田节肢动物功能团优势度比较及产量测定的方法来评价16个水稻品种(系)对褐飞虱Nilaparvata lugens(Stl)的抗性。结果表明,有12个品种(系)对褐飞虱表现为抗级,2个品系表现为中抗。这14个抗虫-中抗的品种(系)在成株期也表现一定的抗虫性,且与对照TN1之间差异显著。本试验条件下,广占63-3S/华恢15、广两优106、Y58S/华15、广两优476、广占63-4S/华恢15这5个品种(系)不仅抗虫性好,而且产量也较高,分别比TN1和主栽品种扬两优6号高63.49%～66.57%和3.47%～11.57%,具有广泛的开发应用前景。     

Genetic mapping of the rice resistance-breaking gene of the brown planthopper Nilaparvata lugens

Host plant resistance has been widely used for controlling the major rice pest brown planthopper (BPH, Nilaparvata lugens). However, adaptation of the wild BPH population to resistance limits the effective use of resistant rice varieties. Quantitative trait locus (QTL) analysis was conducted to identify resistance-breaking genes against the anti-feeding mechanism mediated by the rice resistance gene Bph1. QTL analysis in iso-female BPH lines with single-nucleotide polymorphism (SNP) markers detected a single region on the 10th linkage group responsible for the virulence. The QTL explained from 57 to 84% of the total phenotypic variation. Bulked segregant analysis with next-generation sequencing in F₂ progenies identified five SNPs genetically linked to the virulence. These analyses showed that virulence to Bph1 was controlled by a single recessive gene. In contrast to previous studies, the gene-for-gene relationship between the major resistance gene Bph1 and virulence gene of BPH was confirmed. Identified markers are available for map-based cloning of the major gene controlling BPH virulence to rice resistance.     

Electrical penetration graphs from Nilaparvata lugens on resistant and susceptible rice varieties

The feeding behaviour of Nilaparvata lugens (Stal.) was electronically monitored on three rice varieties showing different levels of resistance in the Philippines, over an 8 h period, using a DC amplifier and a video-assisted observation method to simultaneously record honeydew production.Six electrical penetration graph (EPG) patterns are described by their frequency and amplitude characteristics. Patterns 4 and 5 were associated with the production of two different types of honeydew; basic honeydew containing amino acids was produced during Pattern 4 and acidic honeydew with no amino acids was produced during Pattern 5. These patterns are thought to indicate phloem and xylem ingestion by N. lugens respectively.Insects produced shorter periods of Pattern 4 on moderately resistant IR46 and resistant IR62 rice varieties than on susceptible IR22, although the time taken to produce the first period of Pattern 4 from the start of EPG recording did not differ between varieties. This suggests that N. lugens has the ability to initiate phloem ingestion on all three varieties, but that resistance mechanisms in IR46 and IR62 prevent sustained phloem ingestion, at least within the first 8 h of contact.

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Résumé Le comportement alimentaire de N. lugens Stahl a été enregistré életroniquement pendant 8 heures aux Philippines sur 3 variétés de riz présentant différents degrés de résistance, en utilisant un amplificateur DC associé à un système vidéo pour enregistrer simultanément la production de miellat.Six types d'enregistrements de pénétration (EPG) sont décrits avec leurs caractéristiques de fréquence et d'amplitude. Les types 4 et 5 sont associés à la production de 2 types différents de miellat; le miellat de base contenant des acides aminés est produit pendant le type 4, et le miellat acide sans acides aminés est produit pendant le type 5. On considére que ces types indiquent respectivement l'ingestion de phloème et xylème par N. lugens.Les périodes de type 4 ont été plus courtes sur les variétés modérément résistante IR46 et résistante IR62 que sur la variété sensible IR22, bien que le temps passé à produire la première période de type 4 depuis le début des enregistrements des EPG ne diffère pas suivant les variétés. Ceci laisse penser que N. lugens a la possibilité de commencer la consommation de phloème sur les trois variétés, mais que les mécanismes de résistance chez IR46 et IR62 empêchent une ingestion soutenue de phloème, au moins pendant les 8 premières heures de contact.

     

Development of an ELISA for evaluating the reproductive status of female brown planthopper,Nilaparvata lugens,by measuring vitellogenin and vitellin levels

To evaluate the reproductive status of the female brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), an indirect sandwich enzyme‐linked immunosorbent assay (ELISA) for monitoring vitellogenin (Vg) and vitellin (Vt) was developed by using monoclonal antibodies and polyclonal antiserum made specifically against BPH Vt. The ovarian development of BPH was divided into five stages according to ovariole development and morphological characteristics. Stages I–III, IV, and V represented the pre‐oviposition, peak oviposition, and post‐oviposition stages, respectively. Levels of Vt in the ovary and Vg/Vt in the whole female body during the five ovary stages appeared to relate well with the corresponding ovarian stages, suggesting that ovarian development can be evaluated by measuring ovarian Vt or whole body Vg/Vt in BPH. With this ELISA protocol, the reproductive status of macropterous BPH captured in rice fields during immigration, dwelling, and emigration was determined based on the levels of Vg/Vt in individual females. The females were mainly in stages I and II, as was confirmed by ovarian dissection. Therefore, this study presented an alternative method for evaluating the reproductive status of BPH in rice fields, which is more precise, convenient, and efficient than conventional techniques, such as dissection and classification of ovaries.     

Variation in feeding behaviour of Nilaparvata lugens on resistant and susceptible rice varieties

The feeding behaviour of Nilaparavata lugens was monitored on three rice varieties showing different levels of resistance in the Philippines, using a video-assisted observation method. N. lugens made more frequent, shorter probes on the moderately resistant IR46 and resistant IR62 rice varieties than on the susceptible IR22. Honeydew production was significantly lower on the resistant varieties though insect weight gains in 24 h were similar on IR46 and IR22, both being significantly greater than on the highly resistant variety.Population development, growth index and damage ratings were low on IR62 indicating antibiosis and/or non preference. When IR46 plants were infested as seedlings population increase, growth index and damage ratings were similar to those on the susceptible IR22. When infested at a later stage of plant growth the damage rating showed a moderate level of resistance though some population development was maintained, indicating antibiosis and tolerance. N. lugens started probing less frequently after surface exploration on both resistant varieties than on IR22 suggesting the presence of a resistance factor associated with the surface waxes of these varieties.

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Résumé Le comportement alimentaire de Nilaparvata lugens sur variétés de riz, sensible (IR22), partiellement résistante (IR46) et fortement résistante (IR62), a été contrôlé avec une méthode associant la vidéo à l'observation. N. lugens faisait des piqûres plus fréquentes et plus brèves sur IR46 et IR62, que sur la variété sensible. La production de miellat était significativement plus faible sur les variétés résistantes, bien que les gains de poids des insectes aient été les mêmes en 24 h sur IR46 et IR22, les deux étant significativement supérieurs à celui sur IR62.La croissance de la population, l'indice de croissance et le taux de dégâts étaient tous plus faibles sur IR62, ce qui révèle une antibiose et/ou une absence de préférence. Quand la contamination des IR46 a au lieu au stade semis, la croissance de population, l'indice de croissance et le taux de dégâts étaient semblables à ceux de la variété sensible IR22. Quand la contamination avait lieu à un stade ultérieur, le laux de dégâts révélait un niveau modéré de résistance bien qu'une certaine croissance de population se soit maintenue, ce qui révèle antibiose et tolérance.Après exploration de la surface des feuilles des deux variétés résistantes, N. lugens sondait moins fréquemment que sur IR22, ce qui laisse présumer un facteur de résistance associé aux cires superficielles de ces variétés.

     

虫害诱导的水稻挥发物对褐飞虱的驱避作用

水稻叶片在遭受害虫的危害时,释放一些特异性的挥发性物质。这些挥发性信息物质在调节植物、植食性昆虫及其天敌的相互关系中有重要作用。利用“Y”型嗅觉仪研究了褐飞虱对虫害诱导的11种水稻挥发物（浓度为2 Μl 化合物溶解在100 Μl丙酮溶液中）的行为反应。结果表明,(E)-2-己烯醛、(E)-2-己烯-1-醇、-2-庚醇和水杨酸甲酯等4种化合物对褐飞虱成虫有显著的驱避作用,而(Z)-3-己烯-1-醇、-2-庚酮、柠檬烯、罗勒烯、芳樟醇、-β-子丁香烯和橙花叔醇等7种物质对褐飞虱成虫的选择行为无显著影响。浓度梯度的实验表明,浓度(不同体积的待测化合物用100 Μl丙酮稀释)较低的(E)-2-己烯醛（0.5 Μl、1 Μl）和芳樟醇（05 Μl、1 Μl、5 Μl）对褐飞虱成虫的选择行为无显著影响,而较高浓度的(E)-2-己烯醛（5 Μl、10 Μl）和芳樟醇（10 Μl）对褐飞虱成虫均有明显的驱避作用。     

Electrical penetration graphs indicate that tricin is a key secondary metabolite of rice,inhibiting phloem feeding of brown planthopper,Nilaparvata lugens

Tricin (5,7,4′‐trihydroxy‐3′,5′‐dimethoxyflavone) is a valuable secondary metabolite which is widely present in gramineous plants, including cultivated rice (Oryza sativa L.) (Poaceae). It can defend the rice plant against damage by the brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), one of the most important pests of rice. This study was conducted to elucidate the mechanisms of action of tricin on BPH feeding behavior. BPH feeding behavior in resistant (Rathu Heenati, RHT) and susceptible (Taichuang native 1, TN1) rice varieties and artificial diets was monitored using the electrical penetration graph (EPG) technique. Tricin concentrations in leaves of varieties RHT and TN1 were quantitatively analyzed by liquid chromatography, coupled to tandem mass spectrometric techniques. Six (NP and N1‐5) and four (NP, N1, N2, and N4) types of waveforms occurred during feeding on rice plants and artificial diets, respectively. The tricin concentration of rice varieties was correlated with total and average durations of N4. Moreover, EPG data indicated that tricin significantly increased the duration of non‐probing and pathway periods and strongly inhibited phloem ingestion (N4). The inhibition was strongly dose dependent, resulting in complete suppression of activity in the phloem region when the tricin concentration was increased to 1 g l^?1. This study revealed that tricin disturbed the feeding behavior of BPH mainly by increasing the non‐probe period and inhibiting phloem ingestion. We confirmed the hypothesis that tricin is a ‘stylet probing stimulant’ of rice planthoppers as proposed in previous studies. The information on the ecological effect of tricin from this study may be useful to clarify the resistance mechanism against BPH of RHT and other tricin‐containing rice varieties.     

Quantitative genetic analysis of biotypes of the brown planthopper Nilaparvata lugens: heritability of virulence to resistant rice varieties

The virulence of Nilaparvata lugens Stål (Homoptera: Delphacidae) to a resistant variety of rice, Oryza sativa L., is suggested to be under polygenic control. To determine whether the virulence of N. lugens is a quantitative character that has continuous distribution or a threshold character that has a few discontinuous phenotypic forms and is determined by some underlying continuous variable, I examined the frequency distribution of honeydew excretion that has been used as a measure of ability of attacking the rice plants, and the relationship between honeydew excretion and the oviposition rate of N. lugens females using a japonica rice line Saikai 190 which has a resistance gene Bph 1. The frequency distribution in honeydew excretion significantly differed from the normal distribution, but two distributions below and above 10 mg honeydew excretion for two days did not significantly deviate from normality, suggesting a bimodal distribution. There were significant differences in the proportion of females ovipositing and the number of eggs deposited between the female groups that excreted 0–10 mg honeydew and more than 20 mg honeydew. Within these female groups, however, the reproductive performances were not different. Thus, virulence of N. lugens can be analyzed as a threshold character that has two distinct phenotypes, virulent and avirulent. I estimated the heritabilities of the virulence of N. lugens by parent-offspring regression using the percentage of virulent females in a full-sib family. The estimates of heritability were 0.41 on Saikai 190 and 0.55 on ASD7, carrying the bph 2 gene. These results show that the N. lugens population has substantial genetic variation in virulence. The regression coefficients on female and male parents were similar, suggesting similar genetic contributions by both parents. When the parental families were examined on Saikai 190 and the progeny on ASD7, the regression coefficient approached zero. There may be a low genetic correlation between virulences to the two varieties.     

褐飞虱唾液腺中水稻抗性适应基因的分离

褐飞虱Nilaparvata lugens (Stål)是一种危害水稻的重要害虫, 在取食水稻时其唾液腺分泌的一些物质能激发水稻产生一系列生理生化反应。为了从褐飞虱唾液腺中得到编码这些分泌物的基因, 本研究运用抑制差减杂交法（suppressed subtractive hybridization, SSH）和镜像选择（mirror orientation selection, MOS）法, 分别以取食抗虫水稻B5和敏感水稻TN1的褐飞虱唾液腺cDNA为tester和driver, 构建了一个含有768个克隆子的抑制差减杂交文库。经筛选得到102个EST, 插入序列长250~1 000 bp, 代表35个单基因。其中28个表达上调, 7个表达下调。经GenBank里的blastx在线分析工具分析, 除了约1/3的转录序列没有相匹配的蛋白质外, 其他EST所代表的氨基酸序列与已知蛋白存在不同程度的相似度, 如海藻溏酶、 卵黄蛋白原、 Ca²⁺结合蛋白、 组织蛋白酶B （cathepsin B）、 黏液样蛋白（putative mucin-like protein）、 羧酸酯酶（carboxylesterase）和碳酸酐酶（cah-3 carbonic anhydrase）等, 且多数蛋白含有信号肽, 推测与分泌有关。本研究将为进一步研究刺吸式昆虫中的激发子蛋白奠定了一定的基础。     

Survival rate and stylet penetration behavior of current Korean populations of the brown planthopper,Nilaparvata lugens,on resistant rice varieties

To understand the development of host plant resistance-breaking ability of the current BPH populations in Korea, we conducted nymphal survivorship tests and electrical penetration graph (EPG) studies on susceptible and resistant rice varieties with four different BPH populations, which were collected in the early 1980s (S-BPH) and in 2005, 2006, and 2007. The S-BPH had low survival rates on resistant rice varieties carrying either Bph1 or bph2. However, the current BPH populations have high resistance-breaking ability on the varieties with their elevated survival rates, whereas their survival rates were still low on the other resistant varieties, Gayabyeo (Bph1  the other unknown gene) and Rathu Heenati (Bph3). The EPG analysis also revealed that the ratio of BPH that could reach the phloem sap ingestion waveform (N4-b) within 15 h on the resistant rice varieties containing Bph1 or bph2 was higher in the current BPH populations (16.7–50%) than in the S-BPH population (0-4.2%). However, the pre-reaching time from the penetration start to the first N4-b waveform in the current BPH populations was significantly longer on resistant varieties (Bph1 or bph2) than on susceptible varieties. Furthermore, the total duration of N4-b waveform was significantly shorter on the resistant varieties.From these results, we suggest that, although the current BPHs collected in Korea have a high resistance-breaking ability through the increase of survival rate on resistant rice varieties carrying either Bph1 or bph2, they still have some difficulties feeding on the phloem sap of the resistant rice varieties.     

Brown planthopper, Nilaparvata lugens, resistance in rice cultivar IR64: mechanism and role in successful N. lugens management in Central Luzon, Philippines

We investigated the mechanism of brown planthopper, Nilaparvata lugens (Stål), resistance in the popular rice cultivar IR64, and the current level of resistance of IR64 to N. lugens in a large rice growing area with low brown planthopper populations (Central Luzon, Philippines). In greenhouse experiments with N. lugens populations collected from Central Luzon, IR64 showed slight to moderate levels of antibiosis, antixenosis, and tolerance relative to the cultivars IR22 and Azucena, which contain no major genes for N. lugens resistance. IR64 was also more resistant than IR26 in most experiments, despite the fact that both varieties have the same major gene for N. lugens resistance, Bph1. This confirms that IR64 contains one or more additional, apparently minor, genes for brown planthopper resistance. Our findings also demonstrate that, in an area with low insecticide use, it is not necessary to have high levels of N. lugens resistance, even in a rice cultivar grown by the majority of farmers, to maintain low and stable N. lugens populations.     

RFLP-facilitated investigation of the quantitative resistance of rice to brown planthopper ( Nilaparvata lugens)

Quantitative trait loci (QTLs), conferring quantitative resistance to rice brown planthopper (BPH), were investigated using 160 F₁₁ recombinant inbred lines (RILs) from the Lemont/Teqing cross, a complete RFLP map, and replicated phenotyping of seedbox inoculation. The paternal indica parent, Teqing, was more-resistant to BPH than the maternal japonica parent, Lemont. The RILs showed transgressive segregation for resistance to BPH. Seven main-effect QTLs and many epistatic QTL pairs were identified and mapped on the 12 rice chromosomes. Collectively, the main-effect and epistatic QTLs accounted for over 70% of the total variation in damage scores. Teqing has the resistance allele at four main-effect QTLs, and the Lemont allele resulted in resistance at the other three. Of the main-effect QTLs identified, QBphr5b was mapped to the vicinity of gl1, a major gene controlling leaf and stem pubescence. The Teqing allele controlling leaf and stem pubescence was associated with resistance, while the Lemont allele for glabrous stem and leaves was associated with susceptibility, indicating that this gene may have contributed to resistance through antixenosis. Similar to the reported BPH resistance genes, the other six detected main-effect QTLs were all mapped to regions where major disease resistance genes locate, suggesting they might have contributed either to antibiosis or tolerance. Our results indicated that marker-aided pyramiding of major resistance genes and QTLs should provide effective and stable control over this devastating pest. Received: 10 December 2000 / Accepted: 7 May 2001     

水稻品种对褐飞虱的田间抗性及其生态学机制

评价了7个水稻品种(浙粳22、宜香845、中组14、秀水123、二优倍九、感虫对照品种TN1和抗虫对照品种IR36)在田间成株期对褐飞虱Nilaparvata lugens(Stl)的抗性表现,并初步分析了它们的抗性机制。结果表明,在田间网室人工诱发条件下,浙粳22、宜香845、秀水123和中组14等4个品种的抗性水平与抗虫品种IR36相同,均小于3级,表现为抗虫,而二优培九则与感虫品种TN1相同,表现为感虫。在自然发生条件下的水稻分蘖期至乳熟期,宜香845和中组14上褐飞虱数量仅为TN1上的7.84%～24.44%,秀水123和浙粳22则为TN1上的30.19%～60.27%。在4个抗性品种上褐飞虱的产卵量和卵孵化率明显减少,而若虫存活率仅为TN1上的20%～30%。与IR36相同,4个抗性品种上褐飞虱的若虫存活率和种群增长倍数均显著低于TN1上,说明他们对褐飞虱的抗性主要表现为抗生性。     

Dynamics of imidacloprid resistance and cross-resistance in the brown planthopper, Nilaparvata lugens

Extensive use of imidacloprid for suppressing the brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae), has placed heavy selection pressure on the target insect. A systematic study was carried out to determine imidacloprid resistance dynamics and cross-resistance. Data collected from a 3-year study (2005–2007) showed that in 2005, the resistance levels in Nanning (Guangxi), Haiyan (Zhejiang), and Nanjing and Tongzhou (Jiangsu) populations ranged from 200- to 799-fold compared with the susceptible strain. However, the resistance levels decreased to 135- to 233-fold in 2007, after reduced application of the chemical. A laboratory population was challenged with imidacloprid in successive generations. After 23 generations, the resistance ratio had increased from 200- to 1 298-fold. Continuous selection with imidacloprid could increase the resistance level even more than has already been developed in the population. Stopping selection with imidacloprid led to a rapid decrease of resistance from 759- to 114-fold after 17 generations. Resistance levels then became stable without decreasing any further. A similar result was also obtained from a study involving a field population (resistance ratio = 625-fold) collected from Tongzhou. At first, the population showed a rapid decrease in resistance right after imidacloprid selection was stopped, and then the resistance stabilized at a level of 105–129-fold. More interestingly, resistance increased again when selection was resumed. In addition, the resistant strain selected with imidacloprid showed substantial cross-resistance to imidaclothiz, thiacloprid, and acetamiprid, and slight levels of cross-resistance to dinotefuran and thiamethoxam, but no obvious cross-resistance to nitenpyram, buprofezin, and fipronil. The information from this study is valuable for formulating resistance-management strategies against N. lugens .     

地上部植食者褐飞虱对不同水稻品种土壤线虫群落的影响

地上和地下部生物群落的交互作用对于调控陆地生态过程具有重要作用。在盆栽条件下利用2×2析因设计研究了褐飞虱(Nilaparvata lugens)取食不同水稻品种后对土壤线虫群落的影响。结果表明, 褐飞虱侵害水稻9 d后, 感虫品种(广四和汕优63)的土壤线虫总数、属数及自生线虫(食细菌线虫、食真菌线虫和捕食性线虫)数量增加, 并且一般达到显著水平(P<0.05); 而上述指标在抗虫品种(汕优559和IR36)土壤中则呈现相反的趋势。植食性线虫数量在强感虫品种广四上显著增加(P<0.05), 而在强抗虫品种IR36上显著减少(P<0.05)。褐飞虱和水稻品种对土壤线虫的生态指数(线虫通道指数、Shannon-Wiener指数、成熟度指数、富集指数和结构指数)没有明显影响, 可能与供试土壤线虫群落组成单一及褐飞虱作用时间较短有关。总之, 褐飞虱强烈影响土壤线虫数量、群落组成和营养结构, 并且作用的方向(促进或抑制)和程度依赖于水稻的品种特性, 揭示出地上部植食者的短期侵害将对稻田土壤生态系统的结构和功能产生深远影响。     

Variation of pre-ovipositional period in the brown planthopper, Nilaparvata lugens, collected in tropical, subtropical and temperate Asia

Abstract:  We investigated the pre-ovipositional period of Nilaparvata lugens originating from tropical, subtropical and temperate regions of East and Southeast Asia using laboratory experiments to compare the migration capability of the populations. Macropter females collected in 1992 from Japan and subtropical North Vietnam had a longer immature period than those from tropical Indochina Peninsula, i.e. the day of the first oviposition after eclosion was about 3 days later in the former populations. Populations collected in 1993 and 1994 from Japan, Central and South China, and North Vietnam also had a longer immature period than that of the tropical Malaysian population. Thus, a general trend was demonstrated that macropters originating in temperate and subtropical East Asia had a longer pre-ovipositional period, which is presumably beneficial for pre-reproductive long-distance migration. This finding supports a current hypothesis for the migration system of N. lugens existing in East Asia, which has maintained the capability of long-distance migration throughout years in spite of the disadvantage of prolonged oviposition for multiplication.