Description of female Epermenia uedai Kuroko & Gaedike, 2006 (Epermeniidae) with the record of the host plant

The superfamily Eriophyoidea constitute a group of phytophagous mites of particular economic and evolutionary interest due to their intimate association with host plants and their agricultural importance as harmful or beneficial organisms. Studies on the Eriophyoidea fauna in Brazil started in the early 1900s with botanical works on cecidias and were continued with researchers looking for and reporting on eriophyid mites causing damage to agricultural crops. Therefore, in this annotated checklist, we compile information from just over a century on eriophyid mites reported or described from Brazil. Its purpose is to facilitate plant protection strategies and guide future work on this important group of phytophagous mites. In addition to taxonomy, we present information on host plants and general aspects of cecidia attributed to eriophyoid mites but without genus/species identification. Compilation was based on: i) literature, including papers, books, theses and congress/symposium publications; ii) specimens deposited in mite collections in Brazil. On each species we present: i) suprageneric/generic classification, synonyms and previous genus/era assignments, including references on original and/or additional descriptions; ii) type host plant and other host(s) plant(s) found in the country; iii) host relationships and remarks on symptoms; iv) localities of occurrences at States/Federal District and municipal levels; and v) host plant status in Brazil as well as biomes where they occur or are cultivated. A total of 234 valid eriophyoid mite species are recorded: 196 Eriophyidae, 20 Diptilomiopidae and 18 Phytoptidae, distributed in 92 genera. Host plants comprised 233 species, belonging to 141 genera and 56 plant families. Four new reports of eriophyoid mites in Brazil are presented based on specimens deposited in reference collections. A new combination is presented for Propeaciota secundum (Flechtmann, Amrine Stasny) in the genus Khanthongella. In addition, data on observations and descriptions of 67 cecidias attributed to eriophyoid mites in five states and on 21 plant families are presented. Geographically, the distribution of species reports of eriophyoids around Brazil is highly uneven, with more than 64% of species (151 spp.) in the Southeast region, which surely reflects a lack of research elsewhere. Regarding host plant specificity, 77.7% are reported on only one host species, 88.9% on one host genus and 98.3% on one host family. Regarding host status 64.1% of species are exclusively associated with native host plants, 27% with naturalized or exotic cultivated host plants, and 6.4% from both native and naturalized or exotic host plants.

Epidemiology, phytopathological and molecular differentiation and infection processes of diverse strains of Magnaporthe spp. on wheat and rice

Ectomycorrhizal (ECM) association can improve plant phosphorus (P) nutrition. Polyphosphates (polyP) synthesized in distant fungal cells after P uptake may contribute to P supply from the fungus to the host plant if they are hydrolyzed to phosphate in ECM roots then transferred to the host plant when required. In this study, we addressed this hypothesis for the ECM fungus Hebeloma cylindrosporum grown in vitro and incubated without plant or with host (Pinus pinaster) and non-host (Zea mays) plants, using an experimental system simulating the symbiotic interface. We used 32 P labelling to quantify P accumulation and P efflux and in vivo and in vitro nuclear magnetic resonance (NMR) spectroscopy and cytological staining to follow the fate of fungal polyP. Phosphate supply triggered a massive P accumulation as newly synthesized long-chain polyP in H. cylindrosporum if previously grown under P-deficient conditions. P efflux from H. cylindrosporum towards the roots was stimulated by both host and non-host plants. However, the host plant enhanced 32 P release compared with the non-host plant and specifically increased the proportion of short-chain polyP in the interacting mycelia. These results support the existence of specific host plant effects on fungal P metabolism able to provide P in the apoplast of ectomycorrhizal roots.

The hypothesis that female fruit flies (Family Tephritidae) remain longer and discover fruit more readily on host plants than on non-host plants was examined. Naive, gravid females of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), were released on non-fruiting host and non-host plants in a large outdoor cage. Their behavior within each plant was characterized over 15 min. using a stopwatch and tape recorder. Although medfly females remained longer on one non-fruiting host (mandarin orange) than on one non-fruiting non-host (Norfolk pine), they stayed just as long on another non-fruiting non-host (eldorado) as on mandarin orange. Also, females tended to leave a second non-fruiting host (tomato) more rapidly than eldorado. In one experiment where host fruit (kumquats) were artificially placed on the plant branches, females were just as likely to find such fruit on non-host as on host plants. Thus, medfly females may forage for fruit on host and certain non-host plants in a like fashion, with vegetative characteristics of host plants not necessarily promoting greater fruit finding efficiency.

Volatiles emitted by plants convey an array of information through different trophic levels. Animals such as host-seeking herbivores encounter plumes with filaments from both host and non-host plants. While studies showed a behavioral effect of non-host plants on herbivore host location, less information is available on how a searching insect herbivore perceives and flies upwind to a host-plant odor plume within a background of non-host volatiles. We hypothesized here that herbivorous insects in search of a host-plant can discriminate plumes of host and non-host plants and that the taxonomic relatedness of the non-host have an effect on finding the host. We also predicted that the ratio between certain plant volatiles is cognized as host-plant recognition cue by a receiver herbivorous insect. To verify these hypotheses we measured the wind tunnel response of the moth Argyresthia conjugella to the host plant rowan, to non-host plants taxonomically related (Rosaceae, apple and pear) or unrelated to the host (Pinaceae, spruce) and to binary combination of host and non-host plants. Volatiles were collected from all plant combinations and delivered to the test insect via an ultrasonic sprayer as an artificial plume. While the response to the rowan as a plant was not affected by the addition of any of the non-host plants, the attraction to the corresponding sprayed headspace decreased when pear or apple but not spruce were added to rowan. A similar result was measured toward the odor exiting a jar where freshly cut plant material of apple or pear or spruce was intermixed with rowan. Dose-response gas-chromatography coupled to electroantennography revealed the presence of seven field attractive and seven background non-attractive antennally active compounds. Although the abundance of field attractive and of some background volatiles decreased in all dual combinations in comparison with rowan alone, an increased amount of the background compounds (3E)-4,8-Dimethyl-1,3,7-nonatriene ((E)-DMNT) and (Z)-3-hexenyl acetate was found in the rowan-apple and rowan-pear but not in the rowan-spruce headspace. A higher ratio between the abundance of each field attractive component and that of (E)-DMNT and (Z)-3-hexenyl acetate was measured for rowan and rowan-spruce in contrast to rowan-pear and rowan-apple headspaces. Our result suggests that the ratio between field attractive and background antennaly active volatiles encodes host-plant recognition in our study system.

'Candidatus Liberibacter' Pathosystems at the Forefront of Agricultural and Biological Research Challenges.

Role of induced resistance in interactions of Epilachna vigintioctopunctata with host and non-host plant species

ABSTRACTTranscriptional profiling in “host plant-parasitic plant” interactions is challenging due to the tight interface between host and parasitic plants and the percentage of homologous sequences shared. Dual RNA-seq offers a solution by enablingin silicoseparation of mixed transcripts from the interface region. However, it has to deal with issues related to multiple mapping and cross-mapping of reads in host and parasite genomes, particularly as evolutionary divergence decreases. In this paper, we evaluated the feasibility of this technique by simulating interactions between parasitic and host plants and refining the mapping process. More specifically, we merged host plant with parasitic plant transcriptomes and compared two alignment approaches: sequential mapping of reads to the two separate reference genomes and combined mapping of reads to a single concatenated genome. We consideredCuscuta campestrisas parasitic plant and two host plants of interest such asArabidopsis thalianaandSolanum lycopersicum. Both tested approaches achieved a mapping rate of ∼90%, with only about 1% of cross-mapping reads. This suggests the effectiveness of the method in accurately separating mixed transcriptsin silico.The combined approach proved slightly more accurate and less time demanding than the sequential approach. The evolutionary distance between parasitic and host plants did not significantly impact the accuracy of read assignment to their respective genomes since enough polymorphisms were present to ensure reliable differentiation. This study demonstrates the reliability of dual RNA-seq for studying host-parasite interactions within the same taxonomic kingdom, paving the way for further research into the key genes involved in plant parasitism.AUTHORS SUMMARYHost-parasite plant interactions represents an interesting biological phenomenon to investigate the complex dynamics involved. Moreover, several economically important crops are infected by parasitic plant, resulting in a significant loss of yield. The management of parasitic plant is inseparable from the deep knowledge of the phenomenon. Sophisticated technologies were developed to study these particular interactions characterized by an admixture of tissues in the region of contact between host and parasite. The main issue is represented by dividing this region to accurately distinguish host and parasite. Unfortunately, these technologies are expensive and they required experienced staff. To address this problem, we tested a bioinformatics approach useful to study the class of RNA molecules belonging to the two interacting plants without the need of an expensive and time-consuming physical separation. In more details, we conducted a case study on two different simulated interactions, testing two different approaches per interaction. As a result, we assessed this method (called dual RNA-seq) as a reliablein silicoseparation of mixed RNA sequences belonging to “host plant – parasitic plant” interaction. Moreover, sequences misassigned and/or not assigned, did not represent a significant loss of information and, both dual RNA approaches tested are equally trustworthy.

The highly specialized chrysomelid Ambrostoma quadriimpressum Motschulsky (Coleoptera: Chrysomelidae) is strictly monophagous on elm trees, Ulmus pumila L. (Ulmaceae) and a few of its close relatives. In order to elucidate how the adult beetles find their host plants, we performed both choice and no-choice arena field experiments to examine their spatial maneuvering under seminatural conditions. In the no-choice experiments, three treatments were tested in which individual beetles in thanatosis were released in the vicinity of a host plant, in which they were released facing (1) toward the host, (2) away from the host but toward a black paper column, or (3) away from the host with no standing target in view. Videorecordings of the beetles’ walking tracks showed that a standing visual target in field of vision strongly influenced their behavior. The host plant and black paper column equally attracted beetles released facing toward them. In choice experiments, the beetles randomly moved to both host and non-host plants, as well as to the host plant and the black paper column, indicating that they do not discriminate host plants from a distance. The results suggest that this monophagous beetle locates host plants via orientation to standing visual targets. The results also indicate that the beetle encounters hosts by chance. The benefit of such a host-finding mechanism in light of dispersion and emigration of the beetle is discussed.

American Entomologist • Summer 2009 Trigonalid wasps are a remarkable group of hyperparasitoids with a curious strategy for locating their hosts. While most parasitoids and hyperparasitoids lay their eggs directly on or in their host, trigonalids lay their eggs on foliage, where these eggs are incidentally ingested by herbivorous insect hosts. Other parasitoids have adopted this “scattershot” approach to host location, but their larvae consume their herbivorous host after hatching in the herbivore’s digestive tract. Trigonalids, however, require a third party; larval development requires that the host herbivore simultaneously host a (primary) parasitoid larva of another species. Although the framework for this unusual life history has been described previously, the identities of the herbivorous and parasitoid hosts of trigonalids have remained elusive. Here we present the first host records for the temperate trigonalid hyperparasitoid Orthogonalys pulchella and discuss the evolution of this unusual life history strategy. Trigonalid wasps are hyperparasitoids that are intimately associated with three other organisms over the course of their life cycle: host plant, host caterpillar, and host primary-parasitoid larva. Female trigonalids lay their numerous eggs on foliage (host plant) almost at random in what we call a “scattershot” approach. These eggs are incidentally consumed by herbivorous caterpillars (host caterpillar) as they feed on the host plants. For the trigonalid larva to survive, the host caterpillar has to be parasitized by another parasitoid species (host primary-parasitoid); the trigonalid larva then completes its development by feeding on the host primary-parasitoid (Fig. 1). Hyperparasitoids have not been well studied (Hawkins 1994, Brodeur 2000) and the life histories of trigonalids in particular are almost completely unknown (Carmean and Kimsey 1998). For most trigonalids, it is a mystery as to which hosts (plant, herbivore, and primary-parasitoid) they use in nature. In this article, we present the results of natural history fieldwork in which we were able to elucidate, for the first time, what host plants, host caterpillars, and host primaryparasitoid the trigonalid Orthogonalys pulchella uses to complete its development.

The effects of crop rotations involving two host (lettuce and lavender) and two non-host (cabbage and radish) plants on the development of mycorrhizal infection in host plants were studied in unsterile soil and in sterilized soil with or without rock phosphate and inoculated withGlomus mosseae. As in previous experiments, pre-cropping with non-host plants did not decrease VA infection in the host plants. On the other hand, pre-cropping with a host plant increased VA infection in the same or another host plant grown afterwards. These effects were noted irrespectively of rock phosphate additions and of soil sterilization.

Many rhizosphere microorganisms are capable of producing Indole Acetic Acid which enhances plant growth and they may be developed as biofertilizers to enhance the uptake of nutrients from nutrient poor soils. The direct effect of IAA would include improving seedling vigor and plant growth. Rhizosphere bacteria producing IAA were isolated from Maize, Cucumber, Chili and Soy bean to investigate their effect on nutrition of the host plants in different soils and the effect on seedling vigor and growth of host and non-host plants. Eight isolates from maize, four from cucumber and two each from Soy bean and Chili were obtained following using Salkowski method. They were Staphylococcus sp. (seven), Bacillus sp. (seven), Serratiasp. (one) and Pseudomonas sp. (one). The presence of IAA was confirmed with thin layer chromatography and was quantified using a colorimetric method. The effect on vigor and growth of isolates from different hosts on host and non-host plants was determined using a pot assay where they were cultivated in forest soil inoculated by mixing isolates from different hosts separately. The effect on seedling vigor was investigated also by conducting a glass tube experiment. A hydroponic assay was conducted by inoculating single strains on the roots of their respective host plants to assess their effect on nutrition. Each crop was inoculated with the rhizosphere isolates of the same crop in different soil types. The plants were analyzed for Nitrogen, Phosphorus, Potassium and chlorophyll. Maize isolates generally had a positive effect on vigor and growth of host and non-host plants. Although some pattern in effect was observed the results are irregular and unpredictable. The isolates from Maize, Soy and Cucumber increased the host nutrient levels. The effect of inocula varied with soil type. The highest nutrient absorption of host plants compared to the control was observed in nutrient poor soils. As such these microorganisms may be suitable as bioinoculants which enhance the plant nutrition in nutrient deficient soils. Therefore while IAA forming rhizosphere bacteria are good candidates as bioinoculants, great caution is required in their use the effect is different depending on the inoculum and soil type. Researching in holistic approach is recommended. Keywords: Auxin, Bio fertilizer, Salkowski, Nutrition, Soil

Phytoplasmas are bacterial plant pathogens that have devastating effects on the yields of crops and plants worldwide. They are intracellular parasites of both plants and insects, and are spread among plants by insects. How phytoplasmas can adapt to two diverse environments is of considerable interest; however, the mechanisms enabling the “host switching” between plant and insect hosts are poorly understood. Here, we report that phytoplasmas dramatically alter their gene expression in response to “host switching” between plant and insect. We performed a detailed characterization of the dramatic change that occurs in the gene expression profile of Candidatus Phytoplasma asteris OY-M strain (approximately 33% of the genes change) upon host switching between plant and insect. The phytoplasma may use transporters, secreted proteins, and metabolic enzymes in a host-specific manner. As phytoplasmas reside within the host cell, the proteins secreted from phytoplasmas are thought to play crucial roles in the interplay between phytoplasmas and host cells. Our microarray analysis revealed that the expression of the gene encoding the secreted protein PAM486 was highly upregulated in the plant host, which is also observed by immunohistochemical analysis, suggesting that this protein functions mainly when the phytoplasma grows in the plant host. Additionally, phytoplasma growth in planta was partially suppressed by an inhibitor of the MscL osmotic channel that is highly expressed in the plant host, suggesting that the osmotic channel might play an important role in survival in the plant host. These results also suggest that the elucidation of “host switching” mechanism may contribute to the development of novel pest controls.

Fruit flies have evolved mechanisms using olfactory and visual signals to find and recognize suitable host plants. The objective of the present study was to determine how habitat patterns may assist fruit flies in locating host plants and fruit. The tomato fruit fly, Neoceratitis cyanescens (Bezzi), was chosen as an example of a specialized fruit fly, attacking plants of the Solanaceae family. A series of experiments was conducted in an outdoor field cage wherein flies were released and captured on sticky orange and yellow spheres displayed in pairs within or above potted host or non-host plants. Bright orange spheres mimicking host fruit were significantly more attractive than yellow spheres only when placed within the canopy of host plants and not when either within non-host plants or above both types of plants. Additional experiments combining sets of host and non-host plants in the same cage, or spraying leaf extract of host plant (bug weed) on non-host plants showed that volatile cues emitted by the foliage of host plants may influence the visual response of flies in attracting mature females engaged in a searching behaviour for a laying site and in assisting them to find the host fruit. Moreover, the response was specific to mature females with a high oviposition drive because starved mature females, immature females and males showed no significant preference for orange spheres. Olfactory signals emitted by the host foliage could be an indicator of an appropriate habitat, leading flies to engage in searching for a visual image.

BackgroundCuscuta japonica Choisy (Japanese dodder) is a parasitic weed that damages many plants and affects agricultural production. The haustorium of C. japonica plays a key role during parasitism in host plants; in contrast, some non-host plants effectively inhibit its formation. However, the metabolic differences between normal dodder in host plants and dodder inhibition in non-host plants are largely unknown. Here, we utilized an integrative analysis of transcriptomes and metabolomes to compare the differential regulatory mechanisms between C. japonica interacting with the host plant Ficus microcarpa and the non-host plant Mangifera indica.ResultsAfter parasitization for 24 h and 72 h, the differentially abundant metabolites between these two treatments were enriched in pathways associated with α-linolenic acid metabolism, linoleic acid metabolism, phenylpropanoid biosynthesis, and pyrimidine metabolism. At the transcriptome level, the flavor biosynthesis pathway was significantly enriched at 24 h, whereas the plant–pathogen interaction, arginine and proline metabolism, and MARK signaling-plant pathways were significantly enriched at 72 h, based on the differentially expressed genes between these two treatments. Subsequent temporal analyses identified multiple genes and metabolites that showed different trends in dodder interactions between the host and non-host plants. In particular, the phenylpropanoid biosynthesis pathway showed significant differential regulation between C. japonica in host and non-host plants.ConclusionsThese results provide insights into the metabolic mechanisms of dodder–host interactions, which will facilitate future plant protection from C. japonica parasitism.