Trap Plants Research Articles

Validation of New Zealand Psa forecasting model in Emilia Romagna Region, Italy

A forecasting model to predict the kiwifruit bacterial canker infections was developed in New Zealand. In 2012, we started the validation of such forecasting in the kiwifruit growing areas of Emilia-Romagna Region. Validation was carried over 2012-2014, exposing micro-propagated potted kiwi plantlets under untreated infected plants from march until November and check them for symptom occurrence, along with pathogen isolation on selective growing media and PCR determination on isolated bacterial colony. Over the years 2012-2014, symptoms on plantlets were always observed from March to the first week of June. In the same period, disease symptoms occurred in the untreated kiwifruit adult vines, confirming what observed in potted trap plants. However diagnostic analysis showed that bacteria can be detected in potted trap plants throughout the year (particularly in 2013 and 2014), except some sporadic week during summer even without a rain event. Validation experiment using trap plants allowed to validate the forecasting model during springtime (from March to June) showing a robust correspondence between the model prediction and the symptom occurrence as well as the bacterial inoculum contaminating the trap plants during the growing season.

Occurrence and Distribution of Apolygus lucorum on Weed Hosts and Tea Plants in Tea Plantation Ecosystems.

The mirid bugs are one of the most important piercing–sucking insect pests in tea plantations, which severely reduce the quality and economic benefits of tea. In this study, the mirid bug species in the three tea-producing areas in Shandong Province of China were investigated. The distribution and occurrence of dominant species of mirid bugs on four weed host plants and tea plants Camellia sinensis (L.) O. Kuntze (Theaceae) were also studied in the tea agro-ecosystems. The results showed that Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) was the dominant mirid bug species in the tea growing areas. Apolygus lucorum densities on Humulus scandens (Lour.) (Moraceae) and Artemisia lavandulaefolia DC. (Asteraceae) were relatively higher than those on Conyza canadensis (Linn) Cronq (Asteraceae), Artemisia annua Linn (Asteraceae), and C. sinensis. Host plant switching of A. lucorum in the tea agro-ecosystem was: A. lucorum scattered on and seriously infested tea plants in June and July; A. lucorum largely migrated to and gathered on H. scandens, A. lavandulaefolia, C. canadensis, and A. annua at the flowering stage, and population densities of A. lucorum on these flowering hosts peaked in late September; in October, A. lucorum gradually moved back to flowering tea plants. These results could provide a reference for selecting host plants, such as Artemisia plants, as trap plants for sustainable control of mirid bugs in tea plantations.

Epidemiology of Exobasidium Leaf and Fruit Spot of Rabbiteye Blueberry: Pathogen Overwintering, Primary Infection, and Disease Progression on Leaves and Fruit.

Epidemiological field studies utilizing disease monitoring, spore trapping, and trap plants were conducted on rabbiteye blueberry (Vaccinium virgatum) between 2014 and 2017 to shed light on the epidemiology of Exobasidium leaf and fruit spot, an emerging disease in the southeastern United States caused by the fungus Exobasidium maculosum. Wash plating of field-collected blueberry tissue from the late dormant season through bud expansion showed that the pathogen overwintered epiphytically on blueberry plants in the field, most likely in its yeast-like conidial stage. Agrichemical applications during the dormant season altered epiphytic populations of the pathogen, which correlated directly with leaf spot incidence later in the spring. Disease monitoring of field plants and weekly exposure of potted trap plants revealed that young leaves at the mouse-ear stage were most susceptible to infection, that disease incidence on leaves progressed monocyclically, and that infection periods were associated with rainfall variables such as the number of days per week with ≥1.0 mm of rain or cumulative weekly rainfall. Weekly spore trapping with an Andersen sampler showed that airborne inoculum was detected only after sporulating leaf lesions producing basidiospores were present in the field, suggesting that the primary inoculum is not airborne. The first symptoms on young, green fruit were observed soon after petal fall (requiring removal of the waxy fruit layer to visualize lesions), and visible disease progress on fruit was delayed by 1 to 3 weeks relative to that on leaves. Fruit infection of field plants and trap plants occurred before airborne propagules were detected by spore trapping and before sporulating leaf lesions were present in the field. Hence, this study showed that fruit infections are initiated by the same initial inoculum as leaf infections but it was not possible to conclusively exclude the possibility of a contribution of basidiospore inoculum from leaf lesions to disease progress on later developing fruit. This is one of only a few studies addressing the epidemiology and disease cycle of an Exobasidium sp. in a pathosystem where artificial inoculation has not been possible to date.

Branched broomrape (Orobanche ramosa L.) control in tomato (Lycopersicon esculentum Mill.) by trap crops and other plant species in rotation

Forty-four plant species of 13 families were tested as trap plants reducing Orobanche ramosa L. infestation on tomato under glasshouse conditions. Many species were parasitized but Orobanche shoot number and dry weight were varied. Petroselinum sativum Hoffm and Trifolium alexandrinum L. were the most infested and Origanum syriacum L. and Citrullus vulgaris Schard. the least. Tomato growth was reduced after many tested species and none prevented parasite infection. Parasite shoot number was the highest on tomato followed Anethum graveolens L., C. vulgaris, Cucumis melo var. flexuosus L., Pimpinella anisum L., Sesamum indicum L., Solanum elaeagnifolium Cav., Sorghum vulgare Pers., Spinacia oleracea L., and T. alexandrinum and the lowest after Brassica oleracea L. var. italica Plenck, Brassica rapa L. var. rapa, Capsicum annuum L., Capsicum frutescens L., Cicer arietinum L., Citrullus colocynthis (L.) Schrad., Cucurbita maxima Duch., Cuminum cyminum L., Hordeum vulgare L., Linum usitatissimum L., Spinacia oleracea L. cv. Epinard greant and Vigna sinensis (L.) Savi. Parasite dry weight per shoot was the lowest on tomato grown after C. arietinum, C. frutescens, Cucumis melo L., Hibiscus sabdariffa L., P. anisum and T. alexandrinum but the highest after Cichorium endivia L. var. crispum Lam., Peganum harmala L., S. oleracea cv. Epinard greant, and Zea mays L. Tomato shoot dry weight increased by 126% over parasite-free control following Ecballium elaterium (L.) A. Rich. and parasite infestation reduced by 56% of the Orobanche-infested control. Considering the average of two experiments, high tomato growth and best parasite control (73% reduction) were obtained after V. sinensis. H. sabdariffa, H. vulgare, and S. vulgare reduced both Orobanche infestation and tomato growth.

Supply chain management: A way forward to curtail post-harvest losses and enhance farmers ’income

India over the years witnessed a marked increase in production of perishable high nutrition products like fruits and vegetables but development of cold-chain infrastructure was not strategically directed, for safe handling and to transport these perishable products to markets. A resultant demand supply mismatch emerged across these commodities, contributing to wide spread price fluctuations and inflation. Cold-chain development efforts were earlier focused on building storage capacity for single commodity bulk storages, at production end, eg. potato and dried chilies whereas the larger basket of perishable horticulture requires other infrastructure components to avail of cold-chain as a market linked intervention. It is apparent that post-harvest losses can be reduced through efficient supply chain system from the point of harvest to the point of consumption. even if the country is able to reduce 50% of the losses/wastage from the current levels, the farmer's income will be sustainably enhanced and many rural employment opportunities will be created. In tomato supply chain study, it is concluded that improved practices have been widely adopted on the farm (improved varieties, trellising, marigolds as trap plants), best practices during harvesting (use of maturity indices, careful handling and picking aids), field handling (use of shade) and during the postharvest period (use of plastic crates, shade for sorting/grading practices) can lead to post harvest loss reduction by 10 percentage points and can cater to Vitamin C requirement of 1.6 billion people per year.

Nodule bacteria from the cultured legume Phaseolus dumosus (belonging to the Phaseolus vulgaris cross-inoculation group) with common tropici phenotypic characteristics and symbiovar but distinctive phylogenomic position and chromid

Phaseolus dumosus is an endemic species from mountain tops in Mexico that was found in traditional agriculture areas in Veracruz, Mexico. P. dumosus plants were identified by ITS sequences and their nodules were collected from agricultural fields or from trap plant experiments in the laboratory. Bacteria from P. dumosus nodules were identified as belonging to the phaseoli-etli-leguminosarum (PEL) or to the tropici group by 16S rRNA gene sequences. We obtained complete closed genomes from two P. dumosus isolates CCGE531 and CCGE532 that were phylogenetically placed within the tropici group but with a distinctive phylogenomic position and low average nucleotide identity (ANI). CCGE531 and CCGE532 had common phenotypic characteristics with tropici type B rhizobial symbionts. Genome synteny analysis and ANI showed that P. dumosus isolates had different chromids and our analysis suggests that chromids have independently evolved in different lineages of the Rhizobium genus. Finally, we considered that P. dumosus and Phaseolus vulgaris plants belong to the same cross-inoculation group since they have conserved symbiotic affinites for rhizobia.

Dynamics of Glyphosate Resistance in Lolium perenne: Pollen-Mediated Gene Flow under Field Conditions in Argentina

The genus Lolium has shown a high tendency to evolve resistance to herbicides. Considering the high level of allogamy of L. perenne and the importance of the wind as an agent for pollen dispersion, the aim of this work was to assess and quantify the effective glyphosate-resistant gene flow by pollen in L. perenne under field conditions. Pollen-mediated gene flow from glyphosate-resistant to -susceptible plants was studied using a donor–receptor design. The results indicate that the effective gene flow reached trap plants distanced ≤35 m downwind from the source of pollen. The progeny of receptor plants growing 0 m from the pollen donors showed 13% of individuals with low glyphosate sensitivity. This represents a seven-fold increase in the frequency of glyphosate-resistant individuals found in the progeny of plants isolated during the flowering period (negative control). Similarly, the progenies of plants grown at 15 and 25 m from the source of glyphosate resistance showed an increase in the frequency of resistant plants by about four- and two-fold, respectively. When the receptor plants were located at >35 m, no glyphosate-resistant plants were detected in their progenies. Management should aim for prevention or delay of flowering of glyphosate-resistant plants.

Push-Pull Farming System Controls Fall Armyworm: Lessons from Africa

Fall armyworm (FAW) Spodoptera frugiperda invaded Africa, with the first detections being reported in Central and Western Africa in early 2016, and now affects at least 40 countries in Africa, causing up to total crop loss amounting to over $6.2 billion p.a. FAW is an invasive polyphagous pest that causes damage to economically important crops and has recently been reported in the Indian sub-continent. Effective control of FAW through use of synthetic chemical pesticides and genetically modified crops such as Bt maize faces challenges including improper use, unaffordability by smallholder farmers and development of resistance by the pest. Additionally, dispersal of FAW larvae into the lower maize plant canopy keeps them out of reach of topical insecticide applications. Integrated pest management (IPM) packages like the push-pull technology which eliminate pesticide use, and deploy natural processes are more suitable and cost-effective. Push-pull is a farming system intensification approach that involves attracting insect pests with trap plants (pull) such as Napier grass (Pennisetum purpureum) or Brachiaria grass, while driving them away from the main crop using a repellent intercrop (push), Desmodium spp., commonly known as desmodium, and attracting natural parasitoids and predators to the field. In the rhizosphere, chemicals secreted by desmodium roots inhibit attachment of germinated striga to maize or sorghum roots and abort germination of striga seeds which are rapidly depleted in the soil. Moreover, it improves soil fertility by fixing nitrogen, improving carbon sequestration, organic matter, moisture retention, and soil biota, and prevents further degradation of soil. The climate-adapted push-pull technology significantly reduces plant damage by FAW and is the first IPM management tool for the pest in Africa, and is well suited to agro-ecosystem intensification needs of smallholder mixed farming systems in Africa and beyond. Both the African and the Asian continents provide favourable climatic conditions for sustained reproduction of the FAW, which is expected to result in severe damage to crops; and being a new pest in both continents, it might have few natural enemies. Conventional control methods have limited effectiveness, as explained above. Therefore, an IPM approach that is compatible with mixed cropping farming systems of small and medium scale farmers is necessary. The climate adapted push-pull is the first demonstrated IPM management tool for the FAW in Africa. The technology combines this with other concomitant benefits including control of stemborers and the parasitic striga weeds, improvement of soil health through factors such as nitrogen fixation by desmodium, natural mulching, moisture retention and improvement of soil organic matter and soil biota. The combined benefits, including control of FAW, result in ecologically sustainable higher crop yields, and well suited to agro-ecosystem intensification needs of smallholder mixed farming systems in Africa and beyond.

Isolation, Characterization and Symbiotic Efficiency of Nitrogen-Fixing and Heavy Metal-Tolerant Bacteria from a Coalmine Wasteland

ABSTRACT: Areas affected by coal mining can be recovered by revegetation with leguminous plants associated with nitrogen-fixing bacteria. This study addressed the isolation and characterization of native nitrogen-fixing bacteria from coalmine wasteland under different vegetation restoration approaches using Macroptilium atropurpureum (DC) Urb and Vicia sativa L. as trap plants. The bacteria were characterized and identified on the basis of 16S rRNA sequences. Additionally, nitrogen-fixing strains were characterized for tolerance to high heavy metal and low pH levels, as well as [...]

The role of precipitation, and petal and leaf infections in Sclerotinia stem rot of spring oilseed Brassica crops in Norway

Sclerotinia stem rot (SSR) is the most important disease of oilseed Brassica crops in Norway. Fungicide applications should be aligned with the actual need for control, but the SSR prediction models used lack accuracy. We have studied the importance of precipitation, and the role of petal and leaf infection for SSR incidence by using data from Norwegian field and trap plant trials over several years. In the trials, SSR incidence ranged from 0 to 65%. Given an infection threshold of 25% SSR, regression and Receiver Operating Characteristics (ROC) analysis were used to evaluate different precipitation thresholds. The sum of precipitation two weeks before and during flowering appeared to be a poor predictor for SSR infection in our field and trap plant trials (P = 0.24, P = 0.11, respectively). Leaves from three levels (leaf one, three, five), and petals were collected at three to four different times during flowering from nine field sites over two years and tested for SSR infection with real-time PCR. Percentage total leaf and petal infection explained 57 and 45% of variation in SSR incidence, respectively. Examining the different leaves and petals separately, infection of leaf three sampled at full flowering showed the highest explanation of variation in later SSR incidence (R2 = 65%, P < 0.001). ROC analysis showed that given an infection threshold of 45%, both petal and leaf infection recommended spraying when spraying was actually needed. Combining information on petal and leaf infection during flowering with relevant microclimate factors in the canopy, instead of the sum of precipitation might improve prediction accuracy for SSR.

Midgut Transcriptional Variation of Chilo suppressalis Larvae Induced by Feeding on the Dead-End Trap Plant, Vetiveria zizanioides.

Chilo supprressalis is one of the most important rice pests that causes serious damage to production in the rice growth area of Asia. Vetiver grass (Vetiveria zizanioides) was previously found to effectively attract female adults of C. suppressalis laying eggs on vetiver leaves, while the larvae cannot complete their life cycles by feeding on vetiver, indicating a potential means of controlling this pest. In the present study, the transcriptomes of midguts of rice-fed and vetiver-fed C. suppressalis larvae were profiled, which aimed to clarify the molecular mechanism of vetiver as a dead-end trap plant preliminarily. We found that ingestion of vetiver provoked a robust transcriptional response in the larval midguts, and a total of 1,849 differentially expressed UniGenes were identified. We focused on 12 digestion-related genes, four immune-related genes and three detoxification-related genes. Most of these genes were significantly down regulated in the larval midguts at 6, 8, and 10 days after feeding on vetiver compared to on rice. Transcriptional dynamics suggested that these genes might be involved in toxicity responses following exposure to vetiver. Taken together, this study provides an initial molecular framework for developing biological control strategies for C. suppressalis in an effort to protect economically important rice crops.

Characterization of flavonoids from candidate striga grass in controlling diet legumes Cicer arietinum and Vigna radiata

Akumu AA, Nyambaka H, Kuate SP, Torto B.2018. Characterization of flavonoids from candidate striga grass in controlling diet legumes Cicer arietinum and Vigna radiata.Biofarmasi J Nat Prod Biochem 16: 83-98. In Africa, intercropping of some legumes with cereal plants has been noticed to generate exceptional reduction of Striga invasion and enhanced production of cereal crop. Desmodium uncinatum administers Striga invasion in intercrop with cereals through an allelopathic technique, which includes postsprouting accretion inhibitors emanated from the roots. Having a potential to be a new technique for grass administering, Allelopathy is a natural and environmentally friendly method. A standardized profiling technique based on Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) and Liquid Chromatography coupled with Mass Spectrometry (LC/MS) was utilized to determine flavonoids in extracts of chickpea (Cicer arietinum) and mung bean (Vigna radiata), potential trap plants for Striga grass. Nine flavonoids involving mono-and diglycosyl derivatives of fisetin, baicalein, rhamnetin, isorhamnetin, formononetin, quercetin, isosakuranetin, and sakuranetin were temporarily distinguished. The obtained phenolics were available at concentrations higher than 0.001% of the dry materials. Many of these phenolic mixtures have been claimed to possess human health advantages. These glycosylated flavones are noted for the first time in these two species. The comprehensive analysis of the polar secondary metabolites in these leguminous plants was useful for comprehending their inhibitory chemistry and proposed biosynthesis by C-glucoside characteristics. All the segregated and described mixtures in the diet legume C. arietinum were O-glucosylated. While, Food legume V. radiata should be observed further to see if it can attain Desmodium’s allelopathic ability since it possesses inhibitory chemistry and proposed biosynthesis by C-glucosylation.

Avoiding Unwanted Vicinity Effects With Attract-and-Kill Tactics for Harlequin Bug, Murgantia histrionica (Hahn) (Hemiptera: Pentatomidae).

In the development of an attract-and-kill approach for the management of harlequin bug (HB), Murgantia histrionica (Hahn), we evaluated attraction and retention of HB by pheromone-baited traps in the field. In release-recapture and on-farm experiments, traps with collard plants with lures-containing HB aggregation pheromone (murgantiol = 10,11-epoxy-1-bisabolen-3-ol) arrested and retained more HB than traps with either plant or lure. In order to avoid unwanted vicinity effects (increased feeding injury to neighboring crop plants due to halo or spillover effects), we also investigated two methods of retaining HB that were attracted to traps: a systemic toxicant (neonicotinoid applied to the trap plant as a drench) and a contact toxicant (long-lasting insecticidal netting [LLIN] with incorporated pyrethroid). More HB adults and more HB-feeding injury were observed on collard plants in the vicinity of lures compared with those neighboring lures in combination with a systemic toxicant. This difference indicates that improvements to trap retention acted to mitigate spillover effects, thereby avoiding unwanted vicinity effects. We also conducted laboratory assays in order to estimate the length of exposure to LLIN necessary to knock down HB adults and nymphs, calculating a knockdown time (KDT50) of 78.3, 2.6, and 2.1 s for females, males, and nymphs, respectively.

Effect of Pinus ponderosa afforestation on soilborne Frankia and saprophytic Actinobacteria in Northwest Patagonia, Argentina

Large areas in the extra-Andean region in the forest - steppe ecotone in “Northwestern Argentinean Patagonia” have been replaced by plantations of the exotic conifer Pinus ponderosa which modify soils physical and chemical factors and alter the biodiversity. Considering that in the region occur saprophytic soilborne actinobacteria that play important role as the fixation of atmospheric nitrogen (N2) in symbiosis with native plant species and the production of bioactive molecules in plants rhizosphere, we aimed to study the effect of the plantation on the abundance of the N2 fixer Frankia and on the genus diversity of cultivable rhizospheric actinobacteria. The study was performed with soils of six paired sites with pine plantations and natural neighbor areas (including steppes or shrublands). Abundance of infective Frankia was estimated by evaluating the nodulation capacity of soils, through a plant bioassay using Ochetophila trinervis as trap plant. Isolation trials for saprophytic actinobacteria were performed by applying chemotactic and successive soils dilutions methods. We concluded that P. ponderosa afforestation affect soil actinobacteria. This was mainly evidenced by a decrease in the Frankia nodulation capacity in O. trinervis, which was related to plantation age, to lower soil carbon and nitrogen content, higher available phosphorus, and to a slight decrease in soils pH. Pine plantation influence on the cultivable saprophytic actinobacteria was less clear. The study highlights the importance of soils as source of Frankia and rhizospheric actinobacteria in relation to disturbance caused by pine plantation in natural environments with native actinorhizal plant species.

Suitability of brachiaria grass as a trap crop for management ofChilo partellus

AbstractThe cereal stemborerChilo partellus(Swinhoe) (Lepidoptera:Crambidae) is a major insect pest of sorghum (Sorghum bicolorL.Moench) and maize (Zea maysL.) in Africa. Trap cropping systems have been shown to be a valuable tool in management of this pest. To optimize trap cropping strategies, an understanding of host‐plant preference for moth oviposition and host suitability for larval survival on potential trap plants is a prerequisite. Therefore, we assessed seven brachiaria accessions (Poaceae) for preference byC. partellusmoths and subsequent larval performance. In two‐choice tests with a local open‐pollinated maize variety (cv. Nyamula), significantly higher numbers of eggs were deposited on brachiaria accessions Marandu, Piata, and Xaraes than on maize, whereas fewer eggs were recorded on plants of Mulato II, Mulato I, and Cayman. There was a significant and negative correlation between the trichome density on plant leaves andC. partellusoviposition preference for brachiaria. In addition to poor larval performance on brachiaria, there was no clear ranking in the accessions regarding larval orientation, settling, arrest, and food ingestion and assimilation. First instars did not consume leaf tissues of brachiaria plants but consumed those of maize, which also suffered more stem damage than brachiaria plants. No larvae survived on brachiaria plant tissue for longer than 5 days, whereas 79.2% of the larvae survived on maize. This study highlights the preferential oviposition ofC. partelluson brachiaria plants over maize and the negative effects that these accessions have on subsequent larval survival and development. Our findings support the use of brachiaria as a trap crop for management ofC. partellusthrough a push‐pull technology.

Analysis of metal tolerance in Rhizobium leguminosarum strains isolated from an ultramafic soil.

Natural habitats containing high amounts of heavy metals provide a valuable source of bacteria adapted to deal with metal toxicity. A functional analysis of the population of legume endosymbiotic bacteria in an ultramafic soil was undertaken by studying a collection of Rhizobium leguminosarum bv viciae (Rlv) isolates obtained using pea as trap plant. One of the isolates, Rlv UPM1137, was selected on the basis of its higher tolerance to nickel and cobalt and presence of inducible mechanisms for such tolerance. A random transposon mutagenesis of Rlv UPM1137 allowed the generation of 14 transposant derivatives with increased nickel sensitivity; five of these transposants were also more sensitive to cobalt. Sequencing of the insertion sites revealed that one of the transposants (D2250) was affected in a gene homologous to the cation diffusion facilitator gene dmeF first identified in the metal-resistant bacterium Cupriavidus metallidurans CH34. The symbiotic performance of D2250 and two other transposants bearing single transposon insertions was unaffected under high-metal conditions, suggesting that, in contrast to previous observations in other Rlv strain, metal tolerance in UPM1137 under symbiotic conditions might be supported by functional redundancy between several mechanisms.

Soil characteristics determine the rhizobia in association with different species of Mimosa in central Brazil

To evaluate the influence of soil type on the symbiosis between Mimosa spp. and rhizobia. A greenhouse experiment was carried out with trap plants using seeds of six species of Mimosa and soils from three different locations in central Brazil: Posse, Brasilia and Cavalcante. Plant dry biomass and number of nodules were measured after four months. Symbiotic bacteria were isolated from nodules and their molecular identification was performed. Three housekeeping genes (16S rRNA, recA and gyrB) plus the nodC and nifH symbiotic genes were used to determine the identity of the symbionts and to reconstruct the phylogenetic relationships among the isolated nitrogen-fixing bacteria. Rhizobia from the Betaproteobacterial genus Paraburkholderia (former Burkholderia) and the Alphaproteobacterial genus Rhizobium were isolated from different species of Mimosa. As in previous studies, the phylogenies of their symbiosis-essential genes, nodC and nifH, were broadly congruent with their core housekeeping genes (16S rRNA, recA and gyrB), which suggests limited or no horizontal gene transfer. Edaphic factors such as pH and fertility influenced the occurrence of these unrelated rhizobial types in the nodules on these Mimosa spp. Mimosa species have the ability to associate with different types of rhizobia (α- and β-proteobacteria), suggesting low specificity between host and bacterium in experimental conditions. Soil factors such as pH, nitrogen and fertility seem to favour the predominance of certain types of rhizobia, thus influencing the establishment of symbiotic relationships.

Electrophysiological responses of the rice striped stem borer Chilo suppressalis to volatiles of the trap plant vetiver grass (Vetiveria zizanioides L.)

Vetiver grass (Vetiveria zizanioides L.) was previously found to effectively attract female adults of Chilo suppressalis (Walker), an important pest of rice. To determine the volatile compounds involved in this attraction, electroantennography (EAG) responses to seven synthetic volatiles released from vetiver plants were examined. Our results indicated that the responses of C. suppressalis adult antennae to the different compounds varied widely. The compounds elicited strong EAG responses in female antennae were subsequently selected for further EAG response tests, namely, caryophyllene, β-ocimene, linalool and α-pinene. EAG responses to a combination of these four compounds did not differ significantly from the individual compounds. However, pair combination tests indicated that 0.01 μg μL−1 linalool and 50 μg μL−1 α-pinene, 50 μg μL−1 caryophyllene and 0.01 μg μL−1 linalool, 0.01 μg μL−1 β-ocimene and 0.01 μg μL−1 linalool, and 0.01 μg μL−1 β-ocimene and 50 μg μL−1 caryophyllene elicited significantly greater EAG responses in 3-day female moths compared to the 1-day female. These compound combinations and the corresponding ratios are probably playing an important role in attracting female adults of C. suppressalis to the vetiver grass.

Diversity and Efficiency of Rhizobia Communities from Iron Mining Areas Using Cowpea as a Trap Plant

ABSTRACT Mining is an important economic activity. However, its impact on environment must be accessed, mainly on relevant processes for their sustainability. The objective of this study was to evaluate the diversity and efficiency of symbiotic nitrogen fixing bacterial communities in soils under different types of vegetation in the Quadrilatero Ferrifero: ironstone outcrops, Atlantic Forest, neotropical savanna, and a rehabilitated area revegetated with grass. Suspensions of soil samples collected under each type of vegetation were made in a saline solution [...]

Effect of a protectant copper application on Psa infection of kiwifruit trap plants

Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker of kiwifruit, which is an ongoing threat to New Zealand kiwifruit production. Disease control depends on orchard practices such as removal of visibly diseased material, pruning during low-risk periods, and the application of foliar bactericides. Although the use of copper compounds on Actinidia species (kiwifruit) can cause phytotoxicity, copper-based formulations remain a key component of Psa control in New Zealand. The effect of single copper applications on Psa infection of ‘Hort16A’ trap plants was studied over the Spring of 2014 (Sept—Nov). Psa leaf spots were observed at the beginning of October, appearing first on the untreated plants. Although the copper sprays did not achieve complete protection, particularly as the inoculum built up during November, the copper-sprayed plants always had less disease than the untreated plants.