Undamaged Plants Research Articles

Plant-to-plant defence induction in cotton is mediated by delayed release of volatiles upon herbivory.

Caterpillar feeding immediately triggers the release of volatile compounds stored in the leaves of cotton plants. Additionally, after 1 d of herbivory, the leaves release other newly synthesised volatiles. We investigated whether these volatiles affect chemical defences in neighbouring plants and whether such temporal shifts in emissions matter for signalling between plants. Undamaged receiver plants were exposed to volatiles from plants infested with Spodoptera caterpillars. For receiver plants, we measured changes in defence-related traits such as volatile emissions, secondary metabolites, phytohormones, gene expression, and caterpillar feeding preference. Then, we compared the effects of volatiles emitted before and after 24 h of damage on neighbouring plant defences. Genes that were upregulated in receiver plants following exposure to volatiles from damaged plants were the same as those activated directly by herbivory on a plant. Only volatiles emitted after 24 h of damage, including newly produced volatiles, were found to increase phytohormone levels, upregulate defence genes, and enhance resistance to caterpillars. These results indicate that the defence induction by volatiles is a specific response to de novo synthesised volatiles, suggesting that these compounds are honest signals of herbivore attack. These findings point to an adaptive origin of airborne signalling between plants.

Volatiles emitted by pepper weevil-infested plants and fruit strongly attract the pteromalid parasitoid Jaliscoa hunteri

Among the many ways arthropod pests may signal their whereabouts to natural enemies, the release of specific volatiles by either pests themselves or their infested host plants may represent some of the most valuable cues that dictate biocontrol agent host-attraction, trophic impact and host-specificity. In this study, we sought to elucidate how plant and insect host-specific volatiles mediate attraction of pteromalid wasp, Jaliscoa hunteri to immature pepper weevil, Anthonomus eugenii, an economically important and challenging-to-control pest of cultivated Capsicum sp. pepper crops across North America. To begin, we used an air-entrainment system to collect volatiles released by whole pepper plants infested or not by either egg, L1 or L3 stages of pepper weevil and in the presence or absence of parental adults. The chemical analysis of sample volatiles from pepper plants infested or not with A. eugenii larvae were then compared, and among these, five compounds were identified that had their emission increased from 1.5 to 8.1 times relative to the blend of volatiles emitted by undamaged pepper plants including: linalool, 1-hexanol, 4,8-dimethylnona-1,3,7-triene (DMNT), methyl salicylate, and 4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT). We next conducted Y olfactometer bioassays to compare the attractive potential of volatiles emitted by pepper fruit, infested or not by L1 or L3 immature pepper weevil, as well as by the alternative J. hunteri-rearing host, L3 or L4 immature Callosobruchus maculatus as they developed within infested chickpeas. Olfactometer bioassays showed that J. hunteri females preferred and consistently oriented towards the volatiles derived from pepper fruit infested by both larval stages of pepper weevil compared to the odour of undamaged pepper fruit. The females of J. hunteri also preferred for the odour emitted by chickpeas infested with C. maculatus compared to air. Ultimately this work highlights the considerable value of studying the composition of volatile headspace captures for pest-infested fruit and complimentary Y-tube assays for measuring or even improving the attraction potential of natural enemies to economically or ecologically important host species.

High-resolution kinetics of herbivore-induced plant volatile transfer reveal clocked response patterns in neighboring plants.

Volatiles emitted by herbivore-attacked plants (senders) can enhance defenses in neighboring plants (receivers), however, the temporal dynamics of this phenomenon remain poorly studied. Using a custom-built, high-throughput proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) system, we explored temporal patterns of volatile transfer and responses between herbivore-attacked and undamaged maize plants. We found that continuous exposure to natural blends of herbivore-induced volatiles results in clocked temporal response patterns in neighboring plants, characterized by an induced terpene burst at the onset of the second day of exposure. This delayed burst is not explained by terpene accumulation during the night, but coincides with delayed jasmonate accumulation in receiver plants. The delayed burst occurs independent of day:night light transitions and cannot be fully explained by sender volatile dynamics. Instead, it is the result of a stress memory from volatile exposure during the first day and secondary exposure to bioactive volatiles on the second day. Our study reveals that prolonged exposure to natural blends of stress-induced volatiles results in a response that integrates priming and direct induction into a distinct and predictable temporal response pattern. This provides an answer to the long-standing question of whether stress volatiles predominantly induce or prime plant defenses in neighboring plants, by revealing that they can do both in sequence.

High-resolution kinetics of herbivore-induced plant volatile transfer reveal clocked response patterns in neighboring plants

Volatiles emitted by herbivore-attacked plants (senders) can enhance defenses in neighboring plants (receivers), however, the temporal dynamics of this phenomenon remain poorly studied. Using a custom-built, high-throughput proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) system, we explored temporal patterns of volatile transfer and responses between herbivore-attacked and undamaged maize plants. We found that continuous exposure to natural blends of herbivore-induced volatiles results in clocked temporal response patterns in neighboring plants, characterized by an induced terpene burst at the onset of the second day of exposure. This delayed burst is not explained by terpene accumulation during the night, but coincides with delayed jasmonate accumulation in receiver plants. The delayed burst occurs independent of day:night light transitions and cannot be fully explained by sender volatile dynamics. Instead, it is the result of a stress memory from volatile exposure during the first day and secondary exposure to bioactive volatiles on the second day. Our study reveals that prolonged exposure to natural blends of stress-induced volatiles results in a response that integrates priming and direct induction into a distinct and predictable temporal response pattern. This provides an answer to the long-standing question of whether stress volatiles predominantly induce or prime plant defenses in neighboring plants, by revealing that they can do both in sequence.

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-β-ocimene and two unidentified compounds compared when exposed to Anakin. Aphids were repelled at a higher concentration of trans-β-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 chromosome-scale genome and the genetic resistance machinery against insect herbivores of the Mexican toloache, Datura stramonium.

Plant resistance refers to the heritable ability of plants to reduce damage caused by natural enemies, such as herbivores and pathogens, either through constitutive or induced traits like chemical compounds or trichomes. However, the genetic architecture-the number and genome location of genes that affect plant defense and the magnitude of their effects-of plant resistance to arthropod herbivores in natural populations remains poorly understood. In this study, we aimed to unveil the genetic architecture of plant resistance to insect herbivores in the annual herb Datura stramonium (Solanaceae) through quantitative trait loci mapping. We achieved this by assembling the species' genome and constructing a linkage map using an F2 progeny transplanted into natural habitats. Furthermore, we conducted differential gene expression analysis between undamaged and damaged plants caused by the primary folivore, Lema daturaphila larvae. Our genome assembly resulted in 6,109 scaffolds distributed across 12 haploid chromosomes. A single quantitative trait loci region on chromosome 3 was associated with plant resistance, spanning 0 to 5.17 cM. The explained variance by the quantitative trait loci was 8.44%. Our findings imply that the resistance mechanisms of D. stramonium are shaped by the complex interplay of multiple genes with minor effects. Protein-protein interaction networks involving genes within the quantitative trait loci region and overexpressed genes uncovered the key role of receptor-like cytoplasmic kinases in signaling and regulating tropane alkaloids and terpenoids, which serve as powerful chemical defenses against D. stramonium herbivores. The data generated in our study constitute important resources for delving into the evolution and ecology of secondary compounds mediating plant-insect interactions.

Better Together: Volatile-Mediated Intraguild Effects on the Preference of Tuta absoluta and Trialeurodes vaporariorum for Tomato Plants.

Plant-herbivore interactions have been extensively studied in tomato plants and their most common pests. Tomato plant chemical defenses, both constitutive and inducible, play a role in mediating these interactions. Damaged tomato plants alter their volatile profiles, affecting herbivore preferences between undamaged and damaged plants. However, previous studies on tomato volatiles and herbivore preferences have yielded conflicting results, both in the volatile chemistry itself as well as in the attraction/repellent herbivore response. This study revisits the volatile-mediated interactions between tomato plants and two of their main herbivores: the leafminer Tuta absoluta and the whitefly Trialeurodes vaporariorum. Tomato plant volatiles were analyzed before and after damage by each of these herbivores, and the preference for oviposition (T. absoluta) and settling (T. vaporariorum) on undamaged and damaged plants was assessed both after conspecific and heterospecific damage. We found that both insects consistently preferred damaged plants over undamaged plants. The emission of herbivore-induced plant volatiles (HIPVs) increased after T. absoluta damage but decreased after T. vaporariorum damage. While some of our findings are in line with previous reports, T. absoluta preferred to oviposit on plants damaged by conspecifics, which differs from earlier studies. A comparison of HIPVs emitted after damage by T. absoluta and T. vaporariorum revealed differences in up- or down-regulation, as well as significant variations in specific compounds (12 for T. absoluta and 26 for T. vaporariorum damaged-plants). Only two compounds, β-caryophyllene and tetradecane, significantly varied because of damage by either herbivore, in line with the overall variation of the HIPV blend. Differences in HIPVs and herbivore preferences may be attributed to the distinct feeding habits of both herbivores, which activate different defensive pathways in plants. The plant's challenge in simultaneously activating both defensive pathways may explain the preference for heterospecific damaged plants found in this study, which are also in line with our own observations in greenhouses.

Инструментальный мониторинг дехромации листвы каштана конского обыкновенного при повреждении охридским минером

A comparison of the visual and instrumental assessments of the horse chestnut foliar dechromation degree infested by the Ohrid miner (Cameraria ohridella) was carried out. The data of surveys of model trees for the period 2014–2022 in the Moscow region are compared. A statistically reliable regression relationship between the results of visual and instrumental assessment of dechromation in a long-term series of observations is shown. Instrumental monitoring of the leaves damages during the growing season was carried out based on the assessment of the NDVI vegetation index using the GreenSeeker Handheld® (Trimble) device. The seasonal dynamics of the NDVI index of foliage under Ohrid miner damage is presented on the example of the 2021 season. It is shown that the plants affected by the pest have a shorter growing season, and the average NDVI index for the season is 25...30 % lower than that of undamaged plants. In a nine-year series of observations, it was found that the transition of the NDVI index over the threshold value of 0.4 in plants affected by the Ohrid miner is observed on average 30...40 days earlier than in healthy plants. The possibility of assessing foliage dechromation based on the results of hyperspectral imaging without visualization using the Ocean Insight «Flame» spectrometer is considered. It is shown that the spectral characteristics of the reflectivity of healthy and damaged Ohrid miner leaves differ significantly, which was demonstrated by comparing the spectral brightness curves of reflection. Characteristic spectral zones in the visible and near infrared ranges have been identified, according to which the presence of leaf damage by a miner is successfully identified. It was found that in the near-infrared radiation area, the reflection of damaged leaves are significantly lower than that of healthy leaves, which indicates a decrease in the overall water content of chestnut leaf blades when damaged by pests. According to the results of multi- and hyperspectral surveys, it is possible to automatically determine the lesion of the horse chestnut foliage by the leaf-mining pest Cameraria ohridella.

Comparative Transcriptome Analysis of Defense Response of Potato to Phthorimaea operculella Infestation.

The potato tuber moth (PTM), Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), is one of the most destructive pests of potato crops worldwide. Although it has been reported how potatoes integrate the early responses to various PTM herbivory stimuli by accumulatively adding the components, the broad-scale defense signaling network of potato to single stimuli at multiple time points are unclear. Therefore, we compared three potato transcriptional profiles of undamaged plants, mechanically damaged plants and PTM-feeding plants at 3 h, 48 h, and 96 h, and further analyzed the gene expression patterns of a multitude of insect resistance-related signaling pathways, including phytohormones, reactive oxygen species, secondary metabolites, transcription factors, MAPK cascades, plant-pathogen interactions, protease inhibitors, chitinase, and lectins, etc. in the potato under mechanical damage and PTM infestation. Our results suggested that the potato transcriptome showed significant responses to mechanical damage and potato tuber moth infestation, respectively. The potato transcriptome responses modulated over time and were higher at 96 than at 48 h, so transcriptional changes in later stages of PTM infestation may underlie the potato recovery response. Although the transcriptional profiles of mechanically damaged and PTM-infested plants overlap extensively in multiple signaling pathways, some genes are uniquely induced or repressed. True herbivore feeding induced more and stronger gene expression compared to mechanical damage. In addition, we identified 2976, 1499, and 117 genes that only appeared in M-vs-P comparison groups by comparing the transcriptomes of PTM-damaged and mechanically damaged potatoes at 3 h, 48 h, and 96 h, respectively, and these genes deserve further study in the future. This transcriptomic dataset further enhances the understanding of the interactions between potato and potato tuber moth, enriches the molecular resources in this research area and paves the way for breeding insect-resistant potatoes.

КОНЦЕПЦІЯ ПОБУДОВИ СТРУКТУРНО МІНЛИВОЇ ЕЛЕКТРОЕНЕРГЕТИЧНОЇ СИСТЕМИ УКРАЇНИ

To support the sustainable functioning and development of the energy sector in the conditions of terrorist and military threats, the concept of building a structurally variable electric power system (EPS) is proposed. Structural variability is defined as the ability of the EPS to reproduce such a variety of subsystems and electrical connections between them, which enables the operator to manage the structure of the EPS and, in this way, ensure the stable operation of the electric power industry in conditions of purposeful destructive actions. The concept of a structurally changing EPS is a strategy for anticipating challenges and threats to the sustainable functioning and development of the electric power industry. In order to build a structurally variable EPS, it is proposed to create regional EPSs with their own capacities for production, storage, distribution and supply of electricity in volumes sufficient for consumption by the population, housing and communal services, transport and agriculture within each region. The establishment of the territorial dimensions of individual subsystems, i.e. regional EPS, is determined on the basis of a compromise between the necessary number of such subsystems and connections between them, which ensure the desired degree of variability of the EPS, and the capitalization levels of the regions sufficient to support investment and operating costs for the corresponding regional EPS. It is assumed that the national EPS supports the regional EPS with agreed amounts of maneuvering and reserve capacities and ensures the supply of electricity to enterprises of industrial, construction, transport and other types of economic activity that are of national importance and do not join the regional EPS. In cases of destruction of individual regional power plants, the national power plant, as well as undamaged neighboring regional power plants, together provide the electricity needs of the affected regions. In the structurally variable EPS, uniform rules of behavior of all energy companies as market participants interacting at the national and regional levels should apply. For the organization of such interaction, it is proposed to apply the decomposition of trading platforms and form a distributed electricity market from interconnected upper-level electricity market and regional electricity markets. References 12, figures 6.

Wound-response jasmonate dynamics in the primary vasculature.

The links between wound-response electrical signalling and the activation of jasmonate synthesis are unknown. We investigated damage-response remodelling of jasmonate precursor pools in the Arabidopsis thaliana leaf vasculature. Galactolipids and jasmonate precursors in primary veins from undamaged and wounded plants were analysed usingMS-based metabolomics and NMR. In parallel, DAD1-LIKE LIPASEs (DALLs), which control the levels of jasmonate precursors in veins, were identified. A novel galactolipid containing the jasmonate precursor 12-oxo-phytodienoic acid (OPDA) was identified in veins: sn-2-O-(cis-12-oxo-phytodienoyl)-sn-3-O-(β-galactopyranosyl) glyceride (sn-2-OPDA-MGMG). Lower levels of sn-1-OPDA-MGMG were also detected. Vascular OPDA-MGMGs, sn-2-18:3-MGMG and free OPDA pools were reduced rapidly in response to damage-activated electrical signals. Reduced function dall2 mutants failed to build resting vascular sn-2-OPDA-MGMG and OPDA pools and, upon wounding, dall2 produced less jasmonoyl-isoleucine (JA-Ile) than the wild-type. DALL3 acted to suppress excess JA-Ile production after wounding, whereas dall2 dall3 double mutants strongly reduce jasmonate signalling in leaves distal to wounds. LOX6 and DALL2 function to produce OPDA and the non-bilayer-forming lipid sn-2-OPDA-MGMG in the primary vasculature. Membrane depolarizations trigger rapid depletion of these molecules. We suggest that electrical signal-dependent lipid phase changes help to initiate vascular jasmonate synthesis in wounded leaves.

Semiochemicals from Trichosanthes anguina (Cucurbitaceae) plants influence behavior in Diaphania indica.

First to third instars of Diaphania indica (Saunders) (Lepidoptera: Crambidae) feed on the lower surface of leaves, while fourth and fifth instars gregariously consume leaves of Trichosanthes anguina L. After defoliating, the caterpillar also attacks flowers and fruits of the plant and finally, results in loss of crop yield. Therefore, behavioral responses of D. indica adults were investigated to volatiles from undamaged (UD), insect-damaged (ID, plants after feeding by D. indica larvae) and jasmonic acid (JA) treated T. anguina plants. Females showed attraction to volatiles of UD and ID plants of three T. anguina cultivars [MNSR-1 (MNS), Baruipur Long (BAR) and Polo No. 1 (POLO)] in Y-tube olfactometer bioassays. Females did not show significant negative responses from volatiles of JA treated plants. Females were more attracted to volatiles of ID plants than UD plants. Females showed attraction to volatiles of UD or ID plants compared to JA treated plants. Females were attracted to certain synthetic blends resembling volatiles of insect-damaged MNS, BAR and POLO plants in olfactometer bioassays. Females could not distinguish among these three certain synthetic blends in olfactometer bioassays. A synthetic blend of 3Z-hexen-1-ol, α-pinene, hexyl acetate, benzyl alcohol and 6Z-nonenal at mole ratios of 1.47:1.20:1:1.82:1.21 was prepared at 20 mg/mL dichloromethane and 100 μL when used as lure in funnel traps resulted in the capture of the highest number of D. indica adults in field trails. The earlier five-component chemical lure could be used in traps in an integrated pest management program of the insect pest, D. indica. © 2023 Society of Chemical Industry.

Biotic and abiotic factors shaping bat activity in Maryland soybean fields

AbstractBats are important pest control agents in agriculture. Yet, the underlying fine‐scale biotic and abiotic mechanisms that drive their foraging behaviors and responses to insect outbreaks are unclear. Herbivore‐induced plant volatiles (HIPVs) can attract both invertebrate and vertebrate natural enemies that use the chemical plant cues to locate insect prey. The ability of HIPVs to attract multiple species raises the question of whether they may also be a biotic factor influencing insectivorous bat activity. Additionally, abiotic factors, such as weather conditions, can affect bat activity in agricultural settings, but little is known about how bats respond to shifting environmental conditions on short timescales in this landscape context. Using a model crop system, soybean (Glycine max), our study asked three questions: (1) Which bat species are active in eastern Maryland soybean fields? (2) Is insectivorous bat activity affected by naturally occurring soybean HIPVs and/or synthetic soybean HIPVs (indole or farnesene)? (3) How is insectivorous bat activity affected by hourly weather conditions in this landscape? In soybean fields in eastern Maryland, we created paired treatment plots: HIPV plots (damaged plants or synthetic HIPV dispensers) and control plots (undamaged plants or empty dispensers). We measured bat activity using ultrasonic recorders, summarizing hourly and nightly activity, and detected 10 total species. The most abundant species were big brown/silver‐haired bats (Eptesicus fuscus/Lasionycteris noctivagans). Bat activity did not significantly differ between control and HIPV plots in any of the three experiments. Thus, our results do not support our expectation that bats in eastern Maryland use soybean HIPVs to locate insect prey. However, bat activity did increase with increasing average hourly temperature and wind speed. This initial study of bats and HIPVs, as well as the fine‐scale examination of weather conditions on bat activity, may serve as a guide for future research on bat–plant interactions that can support the development of new strategies for sustainable pest management.

Induction of silicon defences in wheat landraces is local, not systemic, and driven by mobilization of soluble silicon to damaged leaves.

In response to herbivory, many grasses, including crops such as wheat, accumulate significant levels of silicon (Si) as an antiherbivore defence. Damage-induced increases in Si can be localized in damaged leaves or be more systemic, but the mechanisms leading to these differences in Si distribution remain untested. Ten genetically diverse wheat landraces (Triticum aestivum) were used to assess genotypic variation in Si induction in response to mechanical damage and how this was affected by exogenous Si supply. Total and soluble Si levels were measured in damaged and undamaged leaves as well as in the phloem to test how Si was allocated to different parts of the plant after damage. Localized, but not systemic, induction of Si defences occurred, and was more pronounced when plants had supplemental Si. Damaged plants had significant increases in Si concentration in their damaged leaves, while the Si concentration in undamaged leaves decreased, such that there was no difference in the average Si concentration of damaged and undamaged plants. The increased Si in damaged leaves was due to the redirection of soluble Si, present in the phloem, from undamaged to damaged plant parts, potentially a more cost-effective defence mechanism for plants than increased Si uptake.

Attraction of the Air Potato Leaf Beetle, Lilioceris Cheni, (Coleoptera: Chrysomelidae) to leaf Volatiles of the Air Potato, Dioscorea bulbifera.

Air potato, Dioscorea bulbifera L., is an invasive vine found in the southeastern United States and is native to Asia and Africa. The air potato leaf beetle Lilioceris cheni (Coleoptera: Chrysomelidae), is a host specific biological control agent introduced for D. bulbifera control. In this study, odor cues that control the attraction of L. cheni to D. bulbifera were investigated. The first experiment investigated the response of L. cheni to D. bulbifera leaves versus no leaves in the presence or absence of air flow. The experiment showed a significant response of L. cheni to D. bulbifera leaves in the presence of air flow with leaves placed upwind. When air flow and/or leaves were absent, L. cheni dispersed randomly between the upwind and downwind targets, indicating L. cheni uses volatiles from D. bulbifera in host selection. The second experiment investigated L. cheni response to undamaged, larval-damaged, and adult-damaged plants. Lilioceris cheni showed preference to move towards conspecific damaged plants compared to undamaged plants but did not discriminate between larvae-damaged or adult-damaged plants. The third experiment investigated volatile profiles of damaged D. bulbifera plants using gas chromatography coupled with mass spectroscopy. We found significant differences in volatile profiles between adult and larval damaged plants compared to mechanically damaged and undamaged plants, with increases in 11 volatile compounds. However, larval and adult-damaged volatile profiles did not differ. The information acquired during this study could be used to develop strategies to monitor for L. cheni and improve its biological control program.

Tissue-specific regulation of volatile emissions moves predators from flowers to attacked leaves

Plant-predator mutualisms have been widely described in nature.1,2 How plants fine-tune their mutualistic interactions with the predators they recruit remains poorly understood. In the wild potato (Solanum kurtzianum), predatory mites, Neoseiulus californicus, are recruited to flowers of undamaged plants but rapidly move downward when the herbivorous mites, Tetranychus urticae, damage leaves. This "up-down" movement within the plant corresponds to the shift of N.californicus from palynivory to carnivory, as they change from feeding on pollen to herbivores when moving between different plant organs. This up-down movement of N.californicus is mediated by the organ-specific emissions of volatile organic compounds (VOCs) in flowers and herbivory-elicited leaves. Experiments with exogenous applications, biosynthetic inhibitors, and transient RNAi revealed that salicylic acid and jasmonic acid signaling in flowers and leaves mediates both the changes in VOC emissions and the up-down movement of N.californicus. This alternating communication between flowers and leaves mediated by organ-specific VOC emissions was also found in a cultivated variety of potato, suggesting the agronomic potential of using flowers as reservoirs of natural enemies in the control of potato pests.

Biological control of the pear psylla: studies of its natural enemies and aspects of its chemical communication: Doctoral thesis abstract

The pear psylla, Cacopsylla bidens, is one of the pests that has acquired a primary role in pear cultivation. Finding alternate control methods is required because the management of this hemipteran has relied on the usage of chemical control. To meet this demand, these project aims to improve the understanding of the biology, chemical communication and trophic webs of the predator guild to be able to design a biological control strategy. Molecular approaches were used to determine which of the predators present in the orchard was feeding on C. bidens. Likewise, it was sought to determine at what time of the season these natural enemies begin to act. The findings revealed that many predators from the orders Coleoptera and Neuroptera feed on the pest. Chrysoperla externa was the predator that most frequently fed on C. bidens. In turn, it was determined that these predators begin to act in a more relevant way only on the third generation of C. bidens. To anticipate the arrival of C. externa in the season, it was investigated whether the pear tree changed its volatile profile after being damaged by C. bidens. Likewise, the volatile released following Argyrotaenia sphaleropa damage were identified. The results showed that the pear tree modifies its volatile profile, and this alteration is specific to the herbivore. The predator C. externa was evaluated to determine whether this change could elicit a behavioral response, demonstrating that this predator benefits from the change by discriminating between undamaged plants and plants damaged by both herbivores by being more attracted to volatiles released when the plant is damaged by C. bidens. These finding provides critical information that may be used to move towards a more sustainable management of the pest.

RELATIONSHIP BETWEEN SHOOT DAMAGE AND FLOOD TOLERANCE IN SOUTHERN CATTAIL

Recent climate change has caused water level fluctuations in freshwater bodies to become more intense, making it difficult to conserve large aquatic plant communities. Physiological characterization for recovery is important and can be applied to overgrowth. Southern cattail (Typha domingensis) communities contribute to biodiversity and help to purify water. However, overcrowded southern cattail communities become a nuisance to local people as they often block waterways. Proper management is therefore required to control southern cattail communities for optimization of their benefits. In the present study, we investigated the effect of shoot damage treatment on flood tolerance during the vigorous growth stage which occurs in summer. First, as shoots are damaged by bending or cutting when disturbed under natural conditions, damage treatments were carried out by either cutting or bending the plant shoots at 10 cm above the ground surface. The results showed that bending the shoot had the same or greater inhibitory effect as cutting. Second, the shoots were then cut at a height of 10 cm above the ground surface at the start of the experiment and placed in five different water depth conditions from the ground surface to the water surface. As a result, the maximum depth at which damaged shoots displayed considerable growth was 40 cm. Undamaged plants with a shoot length of about 75 cm displayed considerable growth in water depths of up to 60 cm. These information are useful for management of T. domingensis communities for both of control and conservation.

Plant-herbivore interactions: Experimental demonstration of genetic variability in plant-plant signalling.

Plant-herbivore interactions mediated by plant-plant signalling have been documented in different species but its within-species variability has hardly been quantified. Here, we tested if herbivore foraging activity on plants was influenced by a prior contact with a damaged plant and if the effect of such plant-plant signalling was variable across 113 natural genotypes of Arabidopsis thaliana. We filmed the activity of the generalist herbivore Cornu aspersum during 1 h on two plants differing only in a prior contact with a damaged plant or not. We recorded each snails' first choice, and measured its first duration on a plant, the proportion of time spent on both plants and leaf consumption. Overall, plant-plant signalling modified the foraging activity of herbivores in A.thaliana. On average, snails spent more time and consumed more of plants that experienced a prior contact with a damaged plant. However, the effects of plant-plant signalling on snail behaviour was variable: depending on genotype identity, plant-plant signalling made undamaged plants more repellant or attractive to snails. Genome-wide associations revealed that genes related to stress coping ability and jasmonate pathway were associated to this variation. Together, our findings highlight the adaptive significance of plant-plant signalling for plant-herbivore interactions.

Green Leaf Volatile Function in Both the Natural Defense System of Rumex confertus and Associated Insects’ Behavior

Rumex confertus is a rhizomatous, invasive, and difficult to control plant. Nevertheless, for sustainable agriculture, studies to biologically control R. confertus continue. Towards this, considerable attention has been devoted to investigating the emission of a wide array of volatile organic compounds (VOCs) from herbivore-damaged plants, which are known to induce protection measures in neighboring, undamaged plants. The goals of this study are to (1) determine if the profile of green leaf volatiles (GLVs), which are organic compounds naturally produced by undamaged plants, is similar to that provoked by the chemical stimulants Z-jasmone (ZJA) and dihydrojasmone (DJA), (2) establish if the Apion miniatum beetle’s reproductive choices are influenced by their sex and mating status, and (3) assess if chemically stimulated GLV emissions can be used as signals to attract pests to R. confertus for biological control purposes. Synthetic forms of naturally produced Z-jasmone (ZJA) and dihydrojasmone (DJA), which can act as either an attractant or a repellent of various species of insects, were used to treat R. confertus. In olfactory analysis, the behavioral responses of individual insects to mated and unmated insects and to two GLV blends were evaluated. It was found that unmated male insects were fairly equally divided between going for food (Y-tube olfactometer arm with a GLV blend) and opportunities for reproduction (Y-tube olfactometer arm with unmated females). However, an increase in the GLV blend concentration attracted the insects. Meanwhile, unmated females were definitely indifferent to food and, independent of the GLV blend dose, were more interested in reproduction. Mated males, even with weak feed stimuli, increased their reproduction activity, in opposition to mated females. We provide evidence that synthetic GLV blends can be used to attract predators, making their use an effective means to biologically control R. confertus. The idea of applying synthetic GLVs as a biological control is based on the insects’ mutual relationships, which work as follows: (i) mated males fully invade the weed, (ii) reproduction-driven females follow the mated males to R. confertus, and (iii) the unmated males follow the females with the purpose to reproduce. Therefore, all insect groups (mated and unmated males and females) can be induced to invade the weed. Upon feeding, the insects will damage the generative organs of R. confertus. We propose that the use of chemical stimulants to increase GLV emissions can be effectively used for weed (here R. confertus) control by attracting a plant pest (here A. miniatum).