Aphid acceptance of Hordeum genotypes is affected by plant volatile exposure and is correlated with aphid growth

Nineteen genotypes of Hordeum vulgare were characterized as partially resistant or susceptible regarding growth of the bird cherry - oat aphid (Rhopalosiphum padi L.). These genotypes were treated with volatiles from undamaged plants of barley cultivar Alva. Aphid host acceptance (AHA) was significantly affected in seven genotypes, and the magnitude of the effect was positively correlated with aphid growth (AG) in a resistance screening test. Changes in AHA induced by volatiles from the same genotype were also positively correlated with AG. All genotypes were tested as inducers with cultivar Kara as the receiver of volatiles. Five genotypes induced significant reductions in AHA of Kara. The results show that aphids are able to detect changes in responding plants induced by volatiles from another cultivar. Plant volatile interactions may thus be a component of induced resistance to aphids. These interactions could influence the results of experiments used to select for insect-resistant plants in plant breeding programmes

Communication between undamaged plants can elicit changes in volatile emissions from neighbouring plants, thereby altering their susceptibility to aphids

Plant volatiles play an important role in intra- and interspecific plant communication, inducing direct and indirect defenses against insect pests. However, it remains unknown whether volatile interactions between undamaged cultivars alter host plant volatile emissions and their perception by insect pests. Here, we tested the effects of exposure of a spring barley, Hordeum vulgare L., cultivar, Salome, to volatiles from other cultivars: Fairytale and Anakin. We found that exposing Salome to Fairytale induced a significantly higher emission of trans-beta-ocimene and two unidentified compounds compared when exposed to Anakin. Aphids were repelled at a higher concentration of trans-beta-ocimene. Salome exposure to Fairytale had significant repulsive effects on aphid olfactory preference, yet not when Salome was exposed to Anakin. We demonstrate that volatile interactions between specific undamaged plants can induce changes in volatile emission by receiver plants enhancing certain compounds, which can disrupt aphid olfactory preferences. Our results highlight the significant roles of volatiles in plant-plant interactions, affecting plant-insect interactions in suppressing insect pests. This has important implications for crop protection and sustainable agriculture.The airborne interactions between certain undamaged spring barley (Hordeum vulgare L.) cultivars induce changes in volatile emission in receiving plants by enhancing the production of certain ideal volatile organic compounds. These changes trigger strong repellent effects on aphids (Rhopalosiphum padi L.), suggesting the significant roles of volatile-mediated plant-plant interactions in the development of integrated pest management for sustainable agriculture practices

Sustainable plant protection for increased food security in a changing climate

The global climate is changing. Rising temperatures in temperate regions are making headlines, but there are a host of changes that may have even greater impact on a global scale, particularly in regions where food security is already delicately balanced. Rising sea levels, changing patterns of rainfall, availability of water and increasing concentration of carbon dioxide in the atmosphere are all likely to affect the biotic environment upon which we depend

Changed host plant volatile emissions induced by chemical interaction between unattacked plants reduce aphid plant acceptance with intermorph variation

Olfactory orientation by aphids is guided by specific volatile blends released from their hosts. Host plants that co-exist with other plants may be less attractive for aphids due to volatile interactions between neighboring plants which can lead to changes in their volatile emissions. These changes in host plant volatile profiles induced by interactions between undamaged plants could be used to manage aphid populations in crops. When potato plants are exposed to volatiles from onion plants, the volatile profile of potato changes in relation to that of unexposed plants with consistently greater quantities of two terpenoids released. We examined the host plant searching behavior of aphids and showed that induced changes in plant volatile emissions affect aphid behavior. We assessed olfactory responses of winged and wingless aphids, Myzus persicae Sulzer (Hemiptera: Aphididae) to the changed volatile emissions. Both morphs were significantly less attracted to odors of potato plants that had been exposed to volatiles from onion than to odors of unexposed potato plants. Further, both morphs were significantly less attracted to synthetic blends mimicking volatiles emitted by onion-exposed potato plants than to blends mimicking non-exposed controls, and to single compounds emitted in greater quantities by exposed potato. Aphid morphs were repelled differently depending on the concentration of odor sources; winged aphids responded to higher doses than did wingless aphids. The aphid responses to changes in plant volatile profiles induced by neighboring plants may facilitate refinement of habitat manipulation strategies (e.g., intercropping) for integrated pest management to reduce aphid occurrence in crops

The phytopathogen powdery mildew affects food-searching behavior and survival of Coccinella septempunctata

The diet of entomophagous coccinellids is mainly based on aphids and other food sources such as pollen, nectar, or fungal spores. Knowledge of their foraging behavior on plants infected by powdery mildew and their survival on fungal spores is currently limited. In this study, we investigated the olfactory response of Coccinella septempunctata to odor emission of barley plants infected by powdery mildew and their survival on fungal spores in the presence or absence of aphids. Odors released by powdery-mildew infected plants were more attractive for ladybirds compared to those of uninfected controls. After 3days, the survival rate of ladybirds feeding only on powdery-mildew spores was less than 50%, while for ladybirds feeding exclusively on Rhopalosiphum padi aphids, the survival rate was close to 90%. After 15days, the highest survival rate (almost 80%) was observed for ladybirds feeding on plants with both aphids and powdery mildew. Molecular analyses confirmed the presence of fungal spores in ladybird guts when feeding either on powdery mildew or on a mixed diet. Our results provide new insights into foraging behavior of entomophagous coccinellids revealing the potential of powdery mildew to be utilized as important non-essential food in a mixed diet, but also its lethal effect if consumed alone

Eskimi IN in NAD Inuiti

The essay considers the advisability of various names for the Aleut peoples and languages from the perspective of the Slovene language

Slovenščina kot neposlednji jezik: revitalizacija pojma ‘J2’*

One’s second language is either a foreign language one has some fluency in or, less typically, one’s first language affected by attrition, when one cannot but use it as a daily means of exchange with parts of one’s environment.Drugi jezik je govorcu ali tuj jezik, ki ga nekaj že zna, ali, manj tipično, prvi jezik, ki ga nekaj še zna, ko se je z vsaj delom vsakdanjega okolja primoran sporazumevati v njem

Chemical composition of summer truffle (Tuber aestivum Vittad.) from Bosnia and Herzegovina

Ascocarps of summer truffle (Tuber aestivum Vittad.) were found in natural oak and beech forests on calcareous soils, at altitude of 840–850 m, near the town of Šipovo in Bosnia and Herzegovina (B&H), with the help of trained dogs.  Until now, no one in B&H has researched the chemical composition of summer truffle. The aim of the work is to analyze nutritional value, elemental composition, and the assortment of fatty acids in the freshly collected ascocarps and to compare achieved results with the results from the literature related to the summer truffle ascocarps found in some other locations, then with the ascomata of other species of truffles, and with the fruiting bodies of some above-ground edible mushrooms. Chemical analysis showed that Tuber aestivum contains about 75.5 % water and about 25.5 % dry matter. The most common group of compounds were carbohydrates, followed by proteins, while the mineral component and fats were much less presented. Among analyzed elements, the most prevalent was potassium with an average concentration of 26,409 mg/kgDW and the least represented was lead with an average concentration of 0.45 mg/kgDW. The main part of the mineral spectrum consisted of three elements: K, P and Ca, with a share of 95.3 %. In ascocarps of summer truffle, 24 fatty acids were detected, of which 13 were saturated and 11 unsaturated. The ratio of saturated to unsaturated fatty acids was 58.34 % to 41.66 %. The most common among saturated fatty acids was palmitic with a share of 25.89 %, while the most common unsaturated fatty acid was elaidic with a share of 28.17 %. No ingredients have been found in the fruiting bodies that would make them unfit for human consumption in any wa

Olfactory learning of plant genotypes by a polyphagous insect predator

Olfactory learning may allow insects to forage optimally by more efficiently finding and using favourable food sources. Although olfactory learning has been shown in bees, insect herbivores and parasitoids, there are fewer examples from polyphagous predators. In this study, olfactory learning by a predatory coccinellid beetle is reported for the first time. In laboratory trials, adults of the aphidophagous ladybird Coccinella septempunctata did not prefer the odour of one aphid-infested barley cultivar over another. However, after feeding on aphids for 24 h on a cultivar, they preferred the odour of that particular cultivar. The mechanism appeared to be associative learning rather than sensitisation. Although inexperienced ladybirds preferred the odour of an aphid-infested barley cultivar over uninfested plants of the same cultivar, after feeding experience on a different cultivar this preference disappeared. This may indicate the acquisition and replacement of olfactory templates. The odour blends of the different aphid-infested barley cultivars varied qualitatively and quantitatively, providing a potential basis for olfactory discrimination by the ladybird. The results show that predatory coccinellids can learn to associate the odour of aphid-infested plants with the presence of prey, and that this olfactory learning ability is sensitive enough to discriminate variability between different genotypes of the same plant

Great Tits Learn Odors and Colors Equally Well, and Show No Predisposition for Herbivore-Induced Plant Volatiles

Ability to efficiently localize productive foraging habitat is crucial for nesting success of insectivorous birds. Some bird species can use olfaction to identify caterpillar-infested trees by detection of herbivore induced plant volatiles (HIPVs), but these cues probably need to be learned. So far, we know very little about the process of olfactory learning in birds, whether insectivorous species have a predisposition for detecting and learning HIPVs, due to the high ecological significance of these odors, and how olfaction is integrated with vision in making foraging decisions. In a standardized setup, we tested whether 35 wild-caught great tits (Parus major) show any preference for widely abundant HIPVs compared to neutral (non-induced) plant odors, how fast they learn to associate olfactory, visual and multimodal foraging cues with food, and whether the olfactory preferences and learning speed were influenced by bird sex or habitat (urban or rural). We also tested how fast birds switch to a new cue of the same modality. Great tits showed no initial preference for HIPVs compared to neutral odors, and they learned all olfactory cues at a similar pace, except for methyl salicylate (MeSA), which they learned more slowly. We also found no differences in learning speeds between visual, olfactory and multimodal foraging cues, but birds learned the second cue they were offered faster than the first one. Bird sex or habitat had no effect on learning speed or olfactory preference, but urban birds tended to learn visual cues more slowly. We conclude that insectivorous birds utilize olfactory and visual cues with similar efficiency in foraging, and that they probably don't have any special predisposition toward the tested HIPVs. These results confirm that great tits are flexible foragers with good learning abilities