Ultrastructure of the salivary glands of the planthopper,peregrinus maidis (ashmead) (Homoptera : Delphacidae)

The principal salivary gland of the planthopper, Peregrinus maidis (Ashmead) (Homoptera : Delphacidae), comprises 8 acini of only 6 ultrastructurally different acinar types. In these acini, secretory cells contain elongated vacuoles partly lined by microvilli and by microtubule bundles. These vacuoles are apparently connected with extracellular canaliculi deeply invaginated into secretory cells. Canaliculi of each acinus lead to a ductule lumen, which is lined with spiral cuticular intima, surrounded by duct cells. Striated muscle fibers, supplied with small nerve axons and tracheoles, are found in various acini of the principal gland, usually around secretory and duct cells.In the accessory salivary gland, the 2 large secretory cells contain no elongated vacuoles or canaliculi invaginations. However, in their central region, apically, these cells border a large microvilli-lined canal with its own canal cells. This canal is apparently connected with the cuticle-lined accessory duct, formed by duct cells. Nerve axons, but no muscle fibers, are found in the accessory gland and its duct. It is suggested that the system for transporting secretory material within acini of the principal gland, is basically different from that within the accessory gland.     

Host plant interactions of the corn planthopper, Peregrinus maidis Ashm. (Homoptera: Delphacidae) in maize and sorghum agroecosystems

The corn planthopper, Peregrinus maidis (Ashmead) (Homoptera: Delphacidae) causes serious economic losses in corn and sorghum. The insect occurs mostly at humid low elevations in the tropics and coastal areas of subtropical and temperate regions of all continents, the Caribbean Islands, and islands in the Atlantic, Indian, and Pacific Oceans. This review provides a detailed compilation on the chronological progress made in basic and strategic aspects of research on the interactions between P. maidis and various host plants. The nature of damage by P. maidis and its economic impact, ecobiology in relation to host diversity, abiotic, and seasonal interactions; and life tables and alary polymorphism are discussed. Host plant resistance studies indicate that very few sources of resistance to P. maidis have been identified in maize, sorghum, or pearl millet, warranting a need to standardize rapid and reliable screening methods. The behavioral responses vis-à-vis mechanisms of resistance show the predominance of antixenosis for colonization and/or oviposition with variable degrees of antibiosis affecting life cycle parameters of P. maidis on maize and sorghum. The role of morphological traits, physiological mechanisms, and biochemical factors governing resistance are described. Population dynamics based on density-dependent and density-independent interactions are also discussed. In addition, aspects of P. maidis on chemical control, biological control, and trophobiosis interactions are listed. Future thrusts on research approaches are also discussed. Genetic engineering techniques involving lectin genes in the development of transgenic plants, and the molecular mapping of genes conferring resistance to both P. maidis and its transmitted virus diseases may stimulate further research and lead to better understanding of P. maidis—host plant interactions. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Staphylococcus,paramyxovirus-like,rickettsia-like and other structures in Peregrinus maidis (Homoptera,delphacidae)

In an ultrastructural study of the delphacid planthopper, Peregrinus maidis, vector of maize mosaic virus (MMV) and maize stripe virus (MStpV), the following structures were found in several organs of MMV-inoculative, MStpV-inoculative, and noninoculative insects: (a) paramyxovirus-like particles (PLP), (b) filamentous rhabdo-like structures (FRS), (c) spiked double-membrane structures (SDS) that were always associated, and sometimes contiguous, with FRS, and (d) rickettsia-like structures (RLS). In salivary gland acini, the PLP, FRS, and SDS were usually found in extracellular spaces between basal infoldings of plasma membranes, whereas the RLS were intracytoplasmic or intranuclear. The PLP and FRS appeared to bud through plasma membranes. The colony of P. maidis in which these structures were found suffered from retarded development and premature death. Limited trials to isolate a paramyxovirus from this colony were unsuccessful. However, further trials led to the isolation of Staphylococcus sciuri, which proved pathogenic when injected into P. maidis and two cicadellid leafhoppers; Dalbulus maidis and Graminella nigrifrons.     

Pathogenicity of fungal isolates (Ascomycota: Hypocreales) against Peregrinus maidis, Delphacodes kuscheli (Hemiptera: Delphacidae), and Dalbulus maidis (Hemiptera: Cicadellidae), vectors of corn diseases

Preliminary screening assays were carried out on 17 isolates from five fungal species Beauveria bassiana, Lecanicillium muscarium, Metarhizium anisopliae, Isaria farinosa, and I. fumosorosea. The three most effective isolates against Peregrinus maidis (Hemiptera: Delphacidae) were B. bassiana CEP 147, CEP 150, and CEP 189. There were no consistent differences found in males and females regarding fungal susceptibility. However, more females than males were proportionally infected. There was not a correlation between the percentage of conidial germination and the percentage of mortality caused by fungal infection in any of the treatments. Only B. bassiana CEP 147, which caused a cumulative mortality of 69.8 ± 6.4% after 7 days post-inoculation, was selected to be assayed against adults of P. maidis, Delphacodes kuscheli (Hemiptera: Delphacidae), and Dalbulus maidis (Hemiptera: Cicadellidae). In pathogenicity tests significant differences were observed among treatments. After 2 weeks post-inoculation, both D. kuscheli (cumulative mortality of 73.3 ± 9.0%) and P. maidis (cumulative mortality of 68.6 ± 6.7%) were significantly more susceptible than D. maidis (cumulative mortality of 49.9 ± 9.7%) to the selected isolate.     

Effect of nitrogen fertilization of corn on the development, survivorship, fecundity and body weight of Peregrinus maidis (Hom., Delphacidae)

Abstract:  Corn plants, Zea mays L. cv. Saccharata 'Guardian' fertilized with low (100 mg N/l), medium (300 mg N/l) and high (500 mg N/l) nitrogen doses at three times per week were used to study the effect of foliar nitrogen on the development, survivorship, reproduction, intrinsic rate of increase and adult body weight of Peregrinus maidis (Ashmead), a serious pest and the vector of maize stripe tenuvirus and maize mosaic rhabdovirus in tropical and subtropical areas. The results showed that the higher nitrogen treatments resulted in the higher nitrogen concentrations in the plants. The insects that developed on corn plants receiving more nitrogen had a significantly shorter development time and higher immature survival rate and laid significantly more eggs. Plants with higher nitrogen concentration also resulted in significantly greater adult mass. Heavier body weight is advantageous because heavier adult females have greater daily oviposition rates than lighter ones. These life history parameters as well as population intrinsic rate of increase were positively correlated with the nitrogen levels in the treated plants. The differences of adult longevity and preoviposition period among different nitrogen treatments were also significant; however, no significant correlation was found between the nitrogen fertilization rate and adult longevity, as well as preoviposition period.     

Hybridization studies in the planthopper genus Ribautodelphax (Homoptera,Delphacidae)

Seven known Ribautodelphax species and four recently discovered taxa were crossed. Forty-three percent of the interspecific crosses were successful. Interspecific crosses generally resulted in low numbers of hybrids. In some combinations prolonged larval development of the hybrid males was observed. Backcrosses showed that both male and female hybrids were fertile. Reproductive isolation was mainly maintained by premating barriers. Insemination tests revealed that prolonged confinement of males and females lowered mating thresholds. The taxonomic status of the known species and new taxa was shown to be in need of revision. No indications for a hybrid origin of the pseudogamous triploid Ribautodelphax females were found.     

Host plant relations in the planthopper genus Ribautodelphax (Homoptera, Delphacidae)

ABSTRACT. 1. Host plant relations of closely related species and pseudogamous triploid forms of the planthopper genus Ribautodelphax were studied.
2. From field data and experimental results it is concluded that eleven European Ribautodelphax species and undescribed taxa are monophagous or oligophagous on different grass species. Only two Ribautodelphax species are found on the same grass species in the field.
3. Differential host plant relations indicate that four recently discovered taxa are probably true species.
4. Ribautodelphax species show a more restricted host plant range in choice experiments compared with breeding tests.
5. Choice experiments indicate no differences in host plant preference between males and females of two Ribautodelphax species.
6. No differences are found in host plant relations between bisexual species and associated pseudogamous triploid forms.     

Bacterial Symbionts of the Brown Planthopper,Nilaparvata lugens (Homoptera: Delphacidae)

The brown planthopper (Nilaparvata lugens Stål), the most destructive pest of rice, has been identified, including biotypes with high virulence towards previously resistant rice varieties. There have also been many reports of a yeast-like symbiont of N. lugens, but little is known about the bacterial microbes. In this study, we examined the bacterial microbes in N. lugens and identified a total of 18 operational taxonomic units (OTUs) representing four phyla (Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes) by sequencing and analyzing 16S rRNA gene libraries obtained from three populations of N. lugens, which were maintained on the rice varieties TN1, Mudgo, and ASD7. Several of the OTUs were similar to previously reported secondary symbionts of other insects, including an endosymbiont of the psyllid Glycapsis brimblecombei, an Asaia sp. found in the mosquito Anopheles stephensi, and Wolbachia, found in the mite Metaseiulus occidentalis. However, the species and numbers of the detected OTUs differed substantially among the N. lugens populations. Further, in situ hybridization analysis using digoxigenin-labeled probes indicated that OTU 1 was located in hypogastrium tissues near the ovipositor and ovary in biotype 1 insects, while OTU 2 was located in the front of the ovipositor sheath in biotype 2 insects. In addition, masses of bacterium-like organisms were observed in the tubes of salivary sheaths in rice plant tissues that the insects had fed upon. The results provide indications of the diversity of the bacterial microbes harbored by the brown planthopper and of possible associations between specific bacterial microbes and biotypes of N. lugens.Close associations between insects and the microbes they harbor appear to be common. Symbionts have been found to contribute to the nutrition, development, reproduction, speciation, and defense against natural enemies of their host insects (1, 11, 18, 30, 39). The small brown planthopper (Laodelphax striatellus) and the white-backed planthopper (Sogatella furcifrea) also reportedly harbor an alphaproteobacterial Wolbachia symbiont (29) that can be transferred horizontally between different insect species and that affects its hosts'' sexual reproduction, cytoplasmic incompatibility, and immune responses (21, 38, 39).The brown planthopper, Nilaparvata lugens Stål (Homoptera: Delphacidae), is a monophagous insect herbivore of rice (13) that feeds on rice phloem and causes serious damage to rice crops. N. lugens reportedly harbors an intracellular, eukaryotic “yeast-like symbiont” (YLS) in the fat body, which plays a key role in recycling uric acid (3, 33). However, little is known about bacterial symbionts in N. lugens.It has been well recognized that diversity exists within insect species and that “biotypes” or populations that are adapted to or that prefer a particular host can frequently develop (10, 12). The behavioral and physiological responses during insect establishment on plants are feeding, metabolism of ingested food, growth, adult survival, egg production, and oviposition (34). In N. lugens, the biotype is assigned to a population with the ability to damage varieties of rice that carry resistance genes and that were previously resistant to it (5). It has been claimed that some biotypes of N. lugens differ in small morphological features, isozymes, and DNA polymorphisms (6, 25, 36). However, the precise nature of the virulence-conferring mechanisms in N. lugens biotypes (and their modes and stability of inheritance) is not clear. It is interesting to survey symbionts in different biotype populations of N. lugens.Generally, the 16S rRNA gene has been used as a molecular marker enabling the detection of as-yet-uncultured microbes, and it facilitates a profound investigation of microbial diversity (2, 22, 44). We initiated a study using molecular methods to investigate the bacterial symbionts of N. lugens. The major objective of this study was to identify bacterial microbes in N. lugens. The identified bacterial microbes appeared to be associated with different populations of N. lugens and in some cases were located in specific tissues, according to in situ hybridization (ISH) analyses.     

Flight duration of the brown planthopper, Nilaparvata lugens (Homoptera: Delphacidae)

ABSTRACT.

• 1 The brown planthopper, Nilaparvata lugens (Stål), is a major pest of rice in Asia. It is known to make wind-assisted migratory flights each year to colonize the summer rice growing areas of China, Japan and Korea.
• 2 Modelling windborne displacements between rice growing areas in Asia requires migratory behaviour and flight duration to be established for this insect.
• 3 Field and laboratory observations suggest that N. lugens take-off at dusk and that some continue flying for up to 24–26 h if the temperature is ≥ 17°C.
• 4 Trajectories for 10 m above ground level and 1.5 km above mean sea level are used to identify possible sources and, hence, to estimate the flight times of N.lugens caught in nets on ships on the East China Sea in 1973 and 1981.
• 5 Estimated flight times between the sources and the ships ranged from about 9 to 30 h.
• 6 Results suggest that long-distance migration can occur in surface winds, when they are strong, but that long-distance migration is more likely at 1.5 km.
• 7 When simulating windborne displacements of N.lugens, it can be assumed that in areas and at heights where the temperature is ≥ 17°C, some migrants will fly downwind for up to 30 h after a dusk take-off. Others will fly for shorter periods, giving the population as a whole the opportunity to colonize all the rice crops flown over.

     

Biosystematics of the Muellerianella complex (Homoptera, Delphacidae): host-plants, habitats and phenology

Abstract. 1. Ecological differences between closely related species and forms of the planthopper genus MueIlerianella (Delphacidae) were studied.
2. In the field M.brevipennis and M.faimairei are restricted to Deschampsia cespitosa and Holcus lanahis/H.mollis . respectively. M.extrusa is mainly found on Molinia caerulea , but has also been recorded from other grass-species. Triploid all-female forms which reproduce by gynogenesis usually live on Holcus together with M.fairmairei . Other gynogenetic populations were found on Bromus ramosus, Deschampsia flexuosa and Calamagrostis canescens .
3. Breeding experiments showed that the diploid species cannot be maintained on each other's host-plants, but accept other grass-species.
4. Due to overlapping habitat requirements of the host-plants, ecological isolation between the Muellerianella species is incomplete.
5. M.extrusa lives in bogs, moors and forests on poor acid soil. M.brevipennis is found in forests, carr, fens and in extensively managed grasslands. M.faimairei and associated triploid forms occur mainly in grasslands and other man-made habitats. The habitats of all three species are usually wet.
6. In most parts of Europe M.brevipennis and M.extrusa are monovoltine and M.fairmairei is mostly bi-or polyvoltine.     

The distribution and abundance of Delphacidae (Homoptera) in central Argentina

A 3-year field study has been carried out on the distribution and abundance of Delphacidae in central Argentina. Insects were collected along a 300 km transect of seven equally spaced sampling sites. At each sampling station there was one sticky trap 6 m above the ground and five sticky traps 1.5 m above the ground. The sampling frequency was every 6 to 15 days during the spring and summer months and monthly during the rest of the year. Delphacodes kuscheli (vector of a local strain of the maize rough dwarf virus, MRDV-RC), Delphacodes haywardi, Delphacodes balboae, Toya spp., Dicranotropis nigricula and Sogatella kolophon meridiana were collected. Among them, D. kuscheli and Toya spp. comprised 67 and 26% of all the delphacid captured. Delphacodes kuscheli showed a geographical gradient in abundance, coincident with the land management gradient which showed a very heterogeneous landscape (in terms of crop species and land management) dedicated to grain production in the north-eastern part of the study area and a less heterogeneous landscape dedicated to cattle breeding (with large extensions covered with pastures where D. kuscheli reproduces and overwinters) in the south-west. Delphacodes kuscheli showed a high dispersal ability and synchronic dynamics, whereas Toya spp. showed a lower dispersal ability with less synchronic dynamics. The implications for the MRDV-RC transmission is discussed.     

Coexistence of pseudogamous and sexual planthoppers of the genus Ribautodelphax (Homoptera, Delphacidae)

ABSTRACT.

• 1 The occurrence of pseudogamous triploid females in populations of the diploid species Ribautodelphax pungens (Ribaut) was studied throughout Europe.
• 2 Considerable differences in triploid frequencies were found between populations but no regular geographic pattern was discerned.
• 3 Within populations triploid frequencies proved to be stable from generation to generation.
• 4 The twofold reproductive advantage of the pseudogamous triploid females is counterbalanced by active mate discrimination by diploid males against the pseudogamous triploid females in populations with high triploid frequencies.
• 5 Sexual diploid and pseudogamous triploid females showed no differences in phenology.
• 6 Differential winter mortality was found between diploid and triploid larvae.

     

褐飞虱卵黄蛋白的分离及其生化特性

电泳结合不同染色方法证实, 褐飞虱Nilaparvata lugens (Stål)卵黄蛋白为一种糖脂结合蛋白,其分子量约为314 kD,由148 kD、124.5 kD和39.6 kD 3个亚基组成。免疫反应证明,卵黄蛋白只存在于生育期的雌性褐飞虱成虫体内。褐飞虱卵黄蛋白具有种的特异性,其免疫血清与白背飞虱的卵黄蛋白无交叉反应。     

A ribosomal DNA probe to distinguish populations of Rhopalosiphum maidis (Homoptera: Aphididae)

Total DNA from clones of Rhopalosiphum maidis was digested with restriction endonucleases and hybridised with a heterospecific ribosomal DNA probe. DNA banding patterns exhibited sufficient differences to distinguish five different clones, and provided greater resolving power than gel electrophoresis of allozymes. The mechanisms and applications of this marking technique are discussed.     

Genetic control and evolution of acoustic signals in planthoppers (Homoptera: Delphacidae)

Acoustic signals are part of the specific mate recognition system of planthoppers. The genetic control of acoustic signal characters was studied in the planthopperRibautodelphax imitans. Artificial selection for interpulse interval in the female call revealed a large additive genetic component for this polygenic character. Other female call characters showed a correlated response. Some male call characters also appeared to be genetically correlated with the female character selected for, despite the rather different structure of male and female calls. Parent-offspring regression provided significant heritability estimates for those male call characters that also responded to artificial selection in the female call, one of which appeared to be influenced by sex-linked genes. It is argued that the differentiation of this mate recognition system in planthopper populations and species could be the result of founder effects, enabled by the genetic plasticity of the call characters and the existence of a wing length dimorphism in these animals.     

Oxalic acid as a sucking inhibitor of the brown planthopper in rice (Delphacidae, Homoptera)

Oxalic acid, isolated from leaf sheath extract of rice, has been identified as a potent sucking inhibitor against the brown planthopper. Potassium and sodium oxalate at concentrations of 0.1%–0.2% completely inhibited sucking on a 15% sucrose solution. Of twelve aliphatic acids commonly present in plants, only oxalic, maleic, andtrans-aconitic acids at 0.1%, significantly reduced sucking activity while Krebs cycle acids, such as citric, malic, and succinic, did not have any inhibitory effect.

---

Résumé L'acide oxalique, isolé des gaines foliaires du riz, a été identifie comme un puissant inhibiteur de la succion deNilaparvata lugens. Les oxalates de potassium et de sodium aux concentrations de 0,1% et 0,2% inhibent complètement la succion d'une solution de sucrose à 15%. Parmi les douze acides aliphatiques généralement présents dans la plante, seuls les acides oxalique, maleique et trans-aconique réduisent significativement à 0,1% l'activité de succion, tandis que les acides cycliques comme les acides citrique, malique et succinique n'ont pas d'effet inhibiteur.

     

Electroantennogram responses of Nilaparvata lugens (Homoptera: Delphacidae) to plant volatile compounds

Electroantennogram (EAG) recordings were made from the plaque organ receptors of the rice brown plant hopper, Nilaparvata lugens (St?l). The receptors of the distal plaque organ of both male and female hoppers responded to the air from above chopped rice plants, and those of females gave a larger response. Female hoppers, tested with 27 plant volatiles, gave dose-related responses to 16 of the compounds, including a range of green leaf volatiles. The aliphatic aldehydes hexanal and (E)-2-hexenal elicited a larger response than a range of green leaf alcohols. Of the remaining compounds, acetophenone, benzaldehyde, ethyl and methyl benzoate, and amyl and isoamyl acetate were among the most effective in eliciting responses. Receptor recovery times showed some variation between compounds. A comparison of the dose-related response of 16 compounds in paraffin oil and in pentane showed that considerably larger responses were recorded when the highly volatile solvent pentane was used.     

中国皱茎飞虱属一新种（同翅目：飞虱科）

记述采自中国贵州省的飞虱科Ｄｅｌｐｈａｃｉｄａｅ皱茎飞虱属Ｏｐｉｃｏｎｓｉｖａ１新种：白边皱茎飞虱Ｏ．ａｌｂｉｍａｒｇｉｎａｔａ,ｓｐ．ｎｏｖ．。地贵州大学昆虫研究所。