Presence Of Host Plants Research Articles

Gibberellin action‐based strategies show promise in the control of Striga—A major threat to global agriculture

Societal Impact StatementThe root‐parasitic plant Striga hermonthica can cause severe crop failure, leading to significant agricultural and economic losses in Africa. Despite the promising target offered by the Striga seed germination mechanism for developing control methods, effective control methods have yet to be established. For seed germination, Striga must undergo an incubation under warm and humid conditions, a process termed conditioning, which allows it to germinate. Here, we report that the plant hormone gibberellin stimulates the conditioning process in Striga seeds. Our findings suggest that the quantitative control of gibberellin in plants is a promising approach for controlling Striga infestations and may help alleviate substantial threats to food security.Summary The root‐parasitic plant S. hermonthica is a serious agricultural threat in Africa. Although a number of control methods have been employed to combat Striga, there is still a need to develop more effective control methods. Striga seeds germinate only in the presence of host plants, owing to the need for host‐released stimulants, primarily strigolactone. To detect signals from the host, Striga seeds must be exposed to a specific warm, dark, and moist environment, which is known as conditioning. Gibberellin directly promotes germination in many nonparasitic plants, but Striga seeds are insensitive to exogenous gibberellin. Consequently, the role of gibberellin in the germination of Striga seeds is unclear. We demonstrated that the effect of the gibberellin biosynthesis inhibitor paclobutrazol was higher in seeds during the conditioning, compared with those already conditioned, suggesting that gibberellin primarily regulates conditioning rather than germination. The content of an active form gibberellin, gibberellin A4 (GA4) exhibited an increase throughout the conditioning period, and we quantified the elevated expression levels of some gibberellin biosynthesis genes. The GA4 treatment shortened the conditioning period required for strigolactone‐induced seed germination. We also discovered that gibberellin upregulated ShACO1, the gene responsible for ethylene synthesis, during conditioning, and that the inhibition of GR24‐induced germination by the ethylene biosynthesis inhibitor α‐aminoisobutyric acid was gradually alleviated by GA4. Our findings demonstrate that gibberellin is critical for conditioning and germination processes but acts as a minor stimulant in Striga seeds. This study demonstrates the potential of quantitative endogenous gibberellin control for Striga management, providing valuable insights for alleviating food security issues.

Influence of climate, weather and floral associations on pollinator community composition across an elevational gradient

Insect pollinators, which are ectothermic, are especially sensitive to abiotic conditions, which often drive predictable patterns of pollinator species turnover along environmental gradients. However, pollinator activity is also reliant on suitable biotic conditions, such as the presence of host plants. High‐elevation environments provide a useful setting to examine the relative contribution of abiotic and biotic factors in shaping species interactions as they are often characterised by strong environmental gradients over short geographic distances. Here, we examined pollination interaction networks across an elevational gradient from 930–2000 m a.s.l. in southern Australia, to determine the underlying patterns of pollinator activity and their interactions with flowers. Interaction frequency of Diptera increased at high elevations, while interaction frequency of Hymenoptera and Coleoptera decreased. We provide evidence that this elevational pattern of activity is partly driven by floral associations, with interactions dominated by Hymenoptera‐attracting plant families at lower elevations (Proteaceae, Fabaceae) and a Diptera‐attracting family at high elevation (Asteraceae). Pollinator activity was also influenced by weather conditions, with reduced activity for all three orders at lower temperatures, and Diptera active across the broadest range of temperature, humidity and wind conditions. We suggest that changes across elevation gradients in pollinator community composition are driven by both direct responses to abiotic conditions such as temperature, as well as the elevational distribution patterns of associated flowering plants. Despite these distinct shifts in composition of the pollinator assemblage with elevation, pollination network structure was stable across the elevational gradient, with moderate levels of specialisation and low levels of connectance and nestedness present across the gradient. By considering both abiotic conditions and biotic processes, our results provide insight for predicting the impacts of upslope vegetation shifts on pollinator communities in the face of climate change.

Composition of soil Frankia assemblages across ecological drivers parallels that of nodule assemblages in Alnus incana ssp. tenuifolia in interior Alaska.

In root nodule symbioses (RNS) between nitrogen (N)-fixing bacteria and plants, bacterial symbionts cycle between nodule-inhabiting and soil-inhabiting niches that exert differential selection pressures on bacterial traits. Little is known about how the resulting evolutionary tension between host plants and symbiotic bacteria structures naturally occurring bacterial assemblages in soils. We used DNA cloning to examine soil-dwelling assemblages of the actinorhizal symbiont Frankia in sites with long-term stable assemblages in Alnus incana ssp. tenuifolia nodules. We compared: (1) phylogenetic diversity of Frankia in soil versus nodules, (2) change in Frankia assemblages in soil versus nodules in response to environmental variation: both across succession, and in response to long-term fertilization with N and phosphorus, and (3) soil assemblages in the presence and absence of host plants. Phylogenetic diversity was much greater in soil-dwelling than nodule-dwelling assemblages and fell into two large clades not previously observed. The presence of host plants was associated with enhanced representation of genotypes specific to A. tenuifolia, and decreased representation of genotypes specific to a second Alnus species. The relative proportion of symbiotic sequence groups across a primary chronosequence was similar in both soil and nodule assemblages. Contrary to expectations, both N and P enhanced symbiotic genotypes relative to non-symbiotic ones. Our results provide a rare set of field observations against which predictions from theoretical and experimental work in the evolutionary ecology of RNS can be compared.

Yellow Wagtails (Passeriformes, Motacillidae) are indicators of steppe and meadow landscapes

Levels of nesting site selection were identified: landscape level is related to birds’ choice of landscape with yellow, pink, white, and green aspects. Ecosystem level corresponds to the detection of a water body by birds. The birds detect a station with the necessary vegetation association, where grasses and meadow halophytic associations are the basis of vegetation. The local (point) level is caused by the presence of a necessary host plant, which is a protector of birds’ nests. The main signals for the selection of nesting conditions for yellow wagtails as a reflection of semiotics are (in order): landscape – habitats of predominantly yellow, less frequently pink, white and green aspects; ecosystem – proximity of a water body (river, lake, etc.); statistical – halophytic associations. The following aspects of the nesting habitats are considered: ecosystem – proximity to a water body (river, lake, etc.); statistical – halophytic vegetation and grasses on sandy loam, loamy, solonchak soils suitable for nesting holes; local (point) – presence of host plant to protect the nest. Birds select nesting habitats based on the availability of all available signals, which increases the possibility and success of colony formation. The manifestation of semiotics: yellow wagtails in the nesting habitat tend to lose their visibility and dissolve into the background of the biotope, which is a special adaptation against predator attack.

Phytosanitary Risk Analysis for Anoplophora chinensis (Forster, 1771) on fruit crops, broadleaved ornamental and forest tree species for Bulgaria

Bulgaria is a traditional agricultural country, where various types of fruit crops, such as apple (Malus), pear (Pyrus), peach, apricot and plum (Prunus), are hosts to Anoplophora chinensis (citrus longhorned beetle). In addition, Anoplophora chinensis is a serious pest of ornamental and forest tree species, such as poplar (Populus), willow (Salix), maple (Acer), alder (Alnus), birch (Betula), chestnut (Castanea), beech (Fagus), oak (Quercus), rose (Rosa), etc. Anoplophora chinensis (citrus longhorned beetle) is a widespread pest in Southeast Asia with climate types ranging from tropical to temperate. It has been introduced to the United States, but it has been successfully eradicated. In Europe, outbreaks of Anoplophora chinensis have been reported from Italy, Croatia, Denmark, France, Germany, the Netherlands, Switzerland, Turkey and the United Kingdom. The pest has been successfully eradicated in Denmark, Germany, Switzerland, the Netherlands and the United Kingdom. At this moment, there is no evidence that Anoplophora chinensis is present in the area for which the phytosanitary risk analysis is being carried out. The main routes for the entry of Anoplophora chinensis into the EU and Bulgaria are through the commercial exchange and movement of planting material (plant material including bonsai plants) and wood products (including logs, timber, wooden packaging material from solid wood without bark and pallets) from host plants originating in countries with established infestation. The probability of Anoplophora chinenis entering Bulgaria naturally is relatively low, despite the fact that outbreaks of the pest have been found in the Black Sea region of Turkey, since the maximum distance of natural spread of the pest in one year is about 194 m. The presence of host plants, as well as the climatic conditions in Bulgaria, are not a limiting factor, which is why the pest has great potential to enter new areas and/or to adapt to new climatic and/or ecological conditions. In case of entry, establishment and spread of Anoplophora chinensis in Bulgaria, it can have a negative impact, both on fruit production and timber harvesting, as well as on ecology, biodiversity in broadleaved forests and urban landscapes, and last but not least, on the development of the resort industry and tourism. The effect on exports of agricultural produce and timber would also be negative. A possible entry, establishment and spread of Anoplophora chinensis in our country would also affect the financial situation of farmers.

Potential Distribution of the Invasive Species Metcalfa pruinosa (Hemiptera, Flatidae) and Perspectives of its Classical Biocontrol in Ukraine

The study used GIS software and climate projections to assess the distribution potential of the citrus planthopper Metcalfa pruinosa (Say, 1830) in Ukraine, taking into account global climate change. The model showed that climatic conditions in Ukraine meet the requirements of the species in the European part of its range, considering various indicators such as the sum of active temperatures, mean annual temperature and precipitation. The whole territory of Ukraine could potentially be a range for M. pruinosa due to suitable climatic conditions and the presence of host plants, with Zakarpattia, Crimea and the forest and woodland and steppe zones of Ukraine being the most favourable. Current phytosanitary measures are not sufficient to prevent its spread and a pest management system is needed to reduce the damage. The parasitoid Neodryinus typhlocybae (Ashmead, 1893) (Hymenoptera, Dryinidae) from North America could serve as a classical biological control agent, and suitable areas in southern Ukraine have been identified using GIS modelling. To manage the risk effectively, it is recommended that M. pruinosa be added to the list of regulated, non-quarantined pests in Ukraine.

Analysis of Trichoderma harzianum TR 274 secretome to assign candidate proteins involved in symbiotic interactions with Phaseolusvulgaris

Trichoderma spp can colonize host plants protecting them from pathogen infection. This association is accomplished by an exchange of molecules secreted by both the host plant and symbiotic fungus. In the present work, using LC-MS/MS analysis, our research group described a list of proteins secreted by T. harzianum TR274 during association with common bean (Phaseolus vulgaris). The main goal is to describe candidate proteins critical for the formerly mentioned association and understand mechanisms related to hosting plant tissue's colonization and modulation of bean plant defense response or metabolism. T. harzianum TR 274 could colonize common bean roots, increasing the transcript levels of defense-related genes (chit, glu1, and pal). Secretomes were obtained from culture filtrates harvested after the growth of T. harzianum TR 274 in the presence (Secretome of co-cultivation-SCC) or absence (Secretome of fungus condition-SFC) of the host plant. We identified 124 and 190 fungal proteins in SCC and SFC, respectively. A total of 30 proteins were detected only in SCC, and 94 were detected in both secretomes (SCC and SFC). The host plant presence decreases the number and diversity of proteins secreted by T. harzianum. The main functional categories represented are glycoside hydrolases, proteases, oxidoreductases, and SSCPs (Small soluble cysteine-rich secreted proteins). Our results provide a list of protein candidates for functional gene studies and validate their role in interactions between T. harzianum and P. vulgaris. Therefore, it contributes to understanding the main mechanisms of T. harzianum host plant colonization and the modulation of defense response.

SCAN-Clim: a tool to support pest climate suitability analysis based on climate classification.

EFSA pest categorisations and pest risk assessments include the assessment of the potential establishment of plant pests. Together with the presence of host plants, climate suitability analysis is an important element to analyse the likelihood of potential establishment of a pest in an area. One of the main approaches used in EFSA plant health risk assessment is the analysis based on climate classifications i.e. evidencing the occurrence of climates enhancing pest development and persistence in a specific area. SCAN‐Clim is a tool designed to support climate suitability analysis based on climate classifications. The current version is the first prototype of the tool, developed in the R language, currently used to support EFSA climate suitability analysis for pest categorisation and for quantitative pest risk assessment. Tested on over 34 EFSA works, SCAN‐Clim significantly improved the speed of climate suitability maps generation guaranteeing a standardised map format and providing documentation on input/outputs. Further improvements will include the development of an interactive web app accessible through the EFSA R4EU Portal (expected to be delivered in 2022).

Arbuscular mycorrhizal and dark septate endophyte colonization in Artemisia roots responds differently to environmental gradients in eastern and central China

Arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) are two types of root symbiotic fungi that enhance nutrient uptake by host plants and their resistance to biotic and abiotic stresses. However, it remains unclear whether AMF and DSE are synergistic or antagonistic in the presence of host plants to environmental gradients, especially on large geographical scales. To determine the relationships between AMF and DSE and their adaptability on a regional scale, we measured AMF and DSE colonization in the roots of 1023 plants of different species within the Artemisia genus collected from 81 sites across central and eastern China. We used general linear mixed models to analyze the relationships between colonization, and temperature and precipitation conditions. We found no significant correlation between AMF and DSE. The AMF colonization rate followed a significant longitudinal trend, but there was no latitudinal pattern. DSE colonization did not follow any geographical pattern. The AMF colonization rate was positively correlated with temperature and precipitation, whereas it was not significantly correlated with soil. There was no significant correlation between DSE colonization and climate or soil. Our results suggest that AMF and DSE play independent roles in the response of Artemisia to the regional environment. Therefore, studies on mycorrhizal symbiosis should discern the differential responses between AMF and DSE to climate and soil when evaluating the adaptability of the two types of symbiosis on large geographical scales.

Performance of larval parasitoid, Bracon brevicornis on two Spodoptera hosts: implication in bio-control of Spodoptera frugiperda

Successful pest management using parasitoids requires careful evaluation of host-parasitoid interactions. Here, we report the performance of larval ecto-parasitoid wasp, Bracon brevicornis (Wesmael) on important agricultural pests, Spodoptera litura (Fabricius) and S. frugiperda (J.E. Smith). Biology of B. brevicornis was studied on different host instars under laboratory and cage setup. In no-choice assay, the parasitoid development was highest on fifth-instar S. litura larvae as the wasp laid ~ 253 eggs with 62% hatching, 76% pupae formation and 78% adult emergence. Similarly, these parameters were highest on fifth instar S. frugiperda larvae (293 eggs, 57% hatching, 80% pupae formation, 70% adult emergence). In two-choice assay, B. brevicornis preferred fourth or fifth over third instar larvae of both hosts. Successful parasitism depends on host paralysis and suppression of host immunity. B. brevicornis interaction downregulated cellular immunity of both hosts as shown by reduced hemocyte viability and spreading. The percent parasitism rate of B. brevicornis was unaltered in the presence of host plant, Zea mays in cage study. 76 and 84% parasitism was observed on fifth-instar larvae of S. litura and S. frugiperda, respectively. We evaluated the performance of B. brevicornis as a biocontrol agent on S. frugiperda in maize field. Our results show 54% average reduction in infestation after release of B. brevicornis. Taken together, we report the performance of B. brevicornis on important insect pests for the first time in laboratory and field conditions. Our findings indicate that B. brevicornis is a promising candidate for integrated pest management.

Culture-dependent and culture-independent characterization of bacterial community diversity in different types of sandy lands: the case of Minqin County, China

BackgroundMinqin is suffering from a serious desertification, whereas the knowledge about its bacterial community is limited. Herein, based on Nitraria tangutorum and Haloxylon ammodendron from Minqin, the bacterial community diversities in fixed sandy land, semi-fixed sandy land and shifting sandy land were investigated by combining with culture-dependent and culture-independent methods.ResultsMinqin stressed with high salinity and poor nutrition is an oligotrophic environment. Bacterial community in Minqin was shaped primarily by the presence of host plants, whereas the type of plant and sandy land had no marked effect on those, which displayed a better survival in the rhizospheres of N. tangutorum and H. ammodendron. The dominant groups at phyla level were Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, Planctomycetes, Chloroflexi, Acidobacteria and Candidate_division_TM7. The abundance of Firmicutes with ability of desiccation-tolerance was significantly higher in harsh environment, whereas Bacteroidetes were mainly distributed in areas with high nutrient content. The abundances of Proteobacteria and Bacteroidetes were relatively high in the rhizospheres of N. tangutorum and H. ammodendron, which had more plant-growth promoting rhizobacteria. A large number of Actinobacteria were detected, of which the most abundant genus was Streptomyces. The physicochemical factors related to the diversity and distribution of the bacterial community were comprehensively analyzed, such as pH, electrical conductivity, soil organic matter, C/N and sand, and the results indicated that Minqin was more suitable for the growth of N. tangutorum, which should be one of most important sand-fixing plants in Minqin.ConclusionsThe bacterial community diversities in different types of sandy lands of Minqin were comprehensively and systematically investigated by culture-dependent and culture-independent approaches, which has a great significance in maintaining/restoring biological diversity.

Retrospective analysis of factors affecting the distribution of an invasive wood-boring insect using native range data: the importance of host plants

Climate is a critical factor considered in predicting the potential distributions of species. However, the distribution of susceptible host plants is another important constraint in retrospective and predictive analyses of invasive insect pests, particularly for wood-boring insects. In the present study, we first modeled the geographic distribution of the invasive emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), and its susceptible host trees using MaxEnt. We then compared the differences between the predicted and actual distribution of EAB in its native (China) and invaded (the United States and Canada) ranges by incorporating the distribution of its susceptible host plants. Results from our models indicate that: (1) in addition to climatic factors, the presence of susceptible host tree species plays a major role in delineating the pest’s distribution; (2) it is more accurate to project EAB’s potential range distribution by considering the suitability of potential areas for its susceptible host plants; and (3) there is a high risk of EAB expanding its current distribution areas in both its native and invasive ranges. The inclusion of susceptible host plant presence as a factor enables more effective predictive modeling and risk assessment for biological invasions, especially for oligophagous insects.

A Unique Population in a Unique Area: The Alcon Blue Butterfly and Its Specific Parasitoid in the Białowieża Forest.

Caterpillars of the Alcon blue butterfly Phengaris alcon are initially endophytic and feed inside the flowerheads of Gentiana plants, but complete their development as social parasites in the nests of Myrmica ants, where they are fed by workers. Its specific and complicated ecological requirements make P. alcon a very local, threatened species, sensitive to environmental changes. We investigated an isolated and previously unknown population in an area of high nature value-the Białowieża Forest (NE Poland). Using the mark-release-recapture method we estimated the seasonal number of adults at 1460 individuals, and their density (850/ha) was the highest among all populations using G. pneumonanthe studied so far. The site is also unique due to the presence of the specific parasitoid Ichneumon cf. eumerus, and parasitoids are considered the ultimate indicators of the biodiversity of Phengaris systems. Since 75.5% of P. alcon pupae were infested we could estimate the seasonal population of adult wasps at about 4500 individuals. The high abundance of both P. alcon and its parasitoid may be explained by favorable habitat characteristics, i.e., the strong presence of host plants and the high density of nests of Myrmica scabrinodis, which is the only local host ant of the butterfly.

Pot host and media treatments towards kayu papi’s (Exocarpus latifolius R.Br) growth

Kayu papi or shrub sandalwood (Exocarpus latifolius R.Br.) is a hemiparasitic plant, member of Santalacea family which incorporated host plant on their nutrient absorption. Kayu papi is a fragrant wood that can mimic and perhaps substitute sandalwood (Santalum album Linn.). Many studies recorded that exocarpic acid derived from kayu papi is also beneficial as a tuberculosis remedy. However, the information on silvicultural techniques has only been investigated just a few times. This study aimed to examine the effect of host plants and media combination on kayu papi’s growth under the nursery condition. Kayu papi seedlings were planted with five different hosts and control (without host plant) on six different media. The parameters are the height and diameter of the seven-month kayu papi seedlings. The result indicates that host plants significantly affected kayu papi’s growth. The interaction between the host plant (Alternanthera spp.) and media combination latosol soil and manure also significantly promoted the height of kayu papi. While kayu papi grown in grumusol with Saorupus androgynous host showed the highest diameter on average. In conclusion, kayu papi seedlings indicate that host plant presence and particular media optimized their growth.

Butterfly abundance and presence of their host plant at Bantimurung-Bulusaraung National Park, Indonesia

The famous butterfly conservation areas in South Sulawesi, Bantimurung-Bulusaraung National Park, are gradually being replaced by intensively used farmland especially in lowland and submontane regions. The objectives of the research were to identify butterfly species and their host plant served as larvae food, nectar and pollen source in three different altitudes at Bantimurung-Bulusaraung National Park. The research was conducted based on transect methods at Bantimurung-Bulusaraung National Park, Maros Regency, South Sulawesi, Indonesia from April to October 2018. Butterflies and their food were observed in three locations at different altitudes of 0-300 m above sea level (asl), 400-700 m asl, and above 700 m asl. The observation indicates a variation in the butterfly species found in different altitudes based on the presence of host plants. A total of 59 individual butterfly samples collected were divided into four families: Papilionidae (7 species), Pieridae (2 species), Nymphalidae (1 species) and Saturniidae (1 species). A further dispersal study based on seasons is needed in order to build a good taxonomic database for Sulawesi butterflies conservation.

Pest categorisation of non-EU Acleris spp.

The Panel on Plant Health performed a pest categorisation of non‐EU Acleris spp. Acleris is a well‐defined insect genus in the family Tortricidae (Insecta: Lepidoptera). Species can be identified using taxonomic keys based on adult morphology and genitalia. The genus includes 261 species attacking conifers and non‐conifer plants in many areas in the world, among which 40 species are present in the EU. The non‐EU species are collectively listed in Annex IAI of Council Directive 2000/29/EC as Acleris spp. (non‐European). Some species are important defoliators in North America, mainly on conifers but also on several broadleaf trees. Females lay eggs on the leaves or on the bark. The larvae bind together with silk the leaves upon which they feed. Pupation occurs in leaves attached with silk or in the soil. Some species are univoltine; others are bivoltine or multivoltine. Flight capacity is not documented, but outbreak expansion suggests that the adults can probably fly long distances. The main pathways for entry are host plants for planting with or without soil, cut branches, fruits of host plants (including cones), round wood with bark and bark. The presence of host plants and suitable EU climate would allow the establishment of the known non‐EU harmful species. In the literature, nine non‐EU Acleris species are reported as pests on various host plants, namely A. gloverana, A. variana, A. minuta, A. nishidai, A. issikii, A. semipurpurana, A. robinsoniana, A. senescens and A. nivisellana. These non‐EU Acleris spp. satisfy all the criteria to be considered as Union quarantine pests. Concerning the other 212 non‐EU Acleris species, there is scarce information on host plants, pests status and climatic suitability. Measures are in place to prevent the introduction of non‐EU Acleris spp. through the pathways described in the document. As non‐EU Acleris spp. are not present in the EU and plants for planting are not the major pathway for spread, non‐EU Acleris spp. do not meet the criteria to be considered as regulated non‐quarantine pests.

Estimating Monitoring Trap Plume Reach and Trapping Area for Nymphal and Adult Halyomorpha halys (Hemiptera: Pentatomidae) in Crop and Non-crop Habitats.

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), the brown marmorated stink bug, is an invasive polyphagous insect that can cause serious economic injury to specialty and row crops in the United States and globally. To date, H. halys has been managed with repeated insecticide applications. While progress has been made toward development of trap-based monitoring tools to guide management decisions, little is known regarding the trapping area over which a single pheromone-baited trap captures H. halys. We conducted single trap, multiple distance mark-release-recapture experiments; results were used to estimate trapping area for nymphs and adults in sites without host plants present (open field) and for adults in sites with host plants present (apple orchard). Plume reach for pheromone-baited sticky traps was consistently estimated to be <3 m. Maximum dispersive distance in an open field devoid of host plants was estimated to be 40 m for nymphs and 120-130 m for adults resulting in trapping areas of 0.58 ha and 4.83-5.56 ha, respectively. When traps were deployed in association with host plants within the border row of an apple orchard, adult maximum dispersive distance and trapping area was reduced to 70 m and 1.67 ha, respectively. These results indicate that the behavioral response of H. halys to pheromonal stimuli is influenced by the presence of host plants and that trapping area for pheromone-baited traps will likely change relative to the cropping system in which it is deployed. Caution should be taken when extrapolating these results, because the measured values may differ in other crop systems.

Activation of Ralfuranone/Ralstonin Production by Plant Sugars Functions in the Virulence of Ralstonia solanacearum.

Plant pathogenic bacteria possess sophisticated mechanisms to detect the presence of host plants by sensing host-derived compounds. Ralstonia solanacearum, the causative agent of bacterial wilt on solanaceous plants, employs quorum sensing to control the production of the secondary metabolite ralfuranones/ralstonins, which have been suggested to be involved in virulence. Here, we report that d-galactose and d-glucose, plant sugars, activate the production of ralfuranones/ralstonins in R. solanacearum. As a result, two new derivatives, ralfuranone M (1) and ralstonin C (2), were found in the culture extracts, and their structures were elucidated by spectroscopic and chemical methods. Ralstonin C (2) is a cyclic lipopeptide containing a unique fatty acid, (2S,3S,Z)-3-amino-2-hydroxyicos-13-enoic acid, whereas ralfuranone M (1) has a common aryl-furanone structure with other ralfuranones. d-Galactose and d-glucose activated the expression of the biosynthetic ralfuranone/ralstonin genes and in part became the biosynthetic source of ralfuranones/ralstonins. Ralfuranones and ralstonins were detected from the xylem fluid of the infected tomato plants, and their production-deficient mutants exhibited reduced virulence on tomato and tobacco plants. Taken together, these results suggest that activation of ralfuranone/ralstonin production by host sugars functions in R. solanacearum virulence.

Analysis of pest risk for Ukraine Cydia inopinata Heinrich

Goal. Carrying-out of a pest risk analysis (PRA) for Ukraine in relation to Cydia inopinata Heinrich (Manchurian moth) — pest of fruit and ornamental crops, according to the EPPO standard PM 5/3 (5) and improvement of methods for assessing the probability of acclimatization of adventive pest organisms beyond existing areas using modern computer software.&#x0D; Methods. Information and analytical, building electronic maps using GIS technologies.&#x0D; Results. There are cited information about the dangerous quarantine pest of fruit crops C. inopinata absent in Ukraine. The ways of possible penetration of the pest into Ukraine were shown, as well as the presence of host plants on the territory of the state are determined and the climatic conditions corresponding to the possibility of settlement and acclimatization are established. The overall pest spreading rate (increase of the infected area) is difficult to estimate. The possibility of natural distribution of the Cydia inopinata is moderately low, and by the anthropogenic way it is very high. Importation of a pest is possible with fruits that are infected with caterpillars of the Manchurian moth from countries of the pest areal. Plants — the owners of C. inopinata are found throughout Ukraine. They are grown for the production of fruits (on a commercial basis or in private gardens), for decorative purposes (in parks, gardens, in urban greening), found in nature or planted in forest belts. Areas with a high density of host plants are more favorable for the settlement of the pest than those with a low density. Due to the adaptation possibilities, the pest can increase the range of plants — hosts in Ukraine. The area of the Manchurian moth is located in several climatic zones: from the subtropical climate in southern China to the sharply continental in Transbaikalia. The compliance of the climate of the central part of the pest area with the climatic conditions of all regions of Ukraine will contribute to the acclimatization of the pest. The absence of extreme winter temperatures, which are characteristic of part of the range in Siberia and in the north of China, will contribute to an increase of the pest population and its harmfulness. The potential habitat of C. inopinata can be almost the entire territory of Ukraine. The main economic impact in the case of local outbreaks will be in farms engaged in the production of fruit products. Electronic maps of the probable area of the Manchurian moth in Ukraine have been built. A pest risk analysis of C. inopinata Heinrich (Manchurian moth) was carried out according to EPPO PM standard 5/3 (5). It was proposed to provide the pest with the status of a quarantine organism absent in Ukraine, to include the species in the A1 list and make changes to the “List of regulated pests of Ukraine”.&#x0D; Conclusions. The high probability of acclimatization of the Manchurian moth in Ukraine is due to the compliance of the climatic conditions with the pest distribution area and a huge number of host plants throughout the territory. The potential habitat of C. inopinata can be almost the entire territory of Ukraine. As an effective measure, it is possible to ban the import of plant fruits — hosts from countries that are the habitat of the Manchurian moth. Analysis of pest risk for Ukraine C. inopinata (Manchurian moth) identified the need to provide the pest with the status of a quarantine organism absent in Ukraine, include the species on the A1 list and make changes to the “List of regulated pests of Ukraine”.

Trophic level and host specialisation affect beta‐diversity in plant–herbivore–parasitoid assemblages

Abstract Herbivorous insects that feed internally on plant tissues depend on their host plants as food resource and immediate habitat. The parasitoids of these herbivores, in turn, depend both on their host herbivores and on the herbivores' host plants. Thus, we may suppose that herbivores and parasitoids must be more affected by biotic interactions (the biotic filter) than their host plants. Also, resource specialisation can mediate the importance of hosts as biotic filters, since the distribution of specialised consumers is limited to sites occupied by their few host species. Plants and insects were sampled in remnants of the Brazilian Cerrado to address three questions: (i) Does beta‐diversity increase at higher trophic levels? (ii) Is host plant specialisation positively related to the beta‐diversity? (iii) Are trophic level effects on beta‐diversity mediated by host plant specialisation? Appropriate null models were employed to explore the importance of biotic filters associated with resources in explaining the beta‐diversity of higher trophic levels. Beta‐diversity and host plant specialisation were lower for parasitoids than for herbivores, and total beta‐diversity did not differ between herbivores and plants. Null models revealed that the presence of host plants did not constrain overall beta‐diversity patterns. Beta‐diversity of herbivores and parasitoids, however, increased with host specialisation. Our findings indicate that low beta‐diversity of basal trophic levels decreases the effect of biotic filters, allowing consumers to occupy several sites. We also show that the severity of biotic filters is higher for host specialists, which might explain the higher beta‐diversity of herbivores compared to parasitoids.