Phenolic content (flavonoids) from undamaged and damaged leaves from two soybean cultivars (DM 4210; DM 5.8i). Damage was produced by fall armyworm or thrips’ hervibory. Mean levels of quercetin triglycoside (a, b), quercetin diglycosides 1 + 2 (c, d), kaempferol triglycoside (e, f), kaempferol diglycosides 1–4 (g, h), and isorhamnetin triglycoside (i, j) concentrations are shown, with error bars representing 1 SEM (n = 3 for undamaged leaves and n = 4 for damaged ones). p Values of one-way and two-way ANOVAs are shown (G: genotype, H: hervibory). In f, g, h, and j, different letters indicate differences within the genotype factor (Tukey test, p value < 0.05)

Phenolic content (flavonoids) from undamaged and damaged leaves from two soybean cultivars (DM 4210; DM 5.8i). Damage was produced by fall armyworm or thrips’ hervibory. Mean levels of quercetin triglycoside (a, b), quercetin diglycosides 1 + 2 (c, d), kaempferol triglycoside (e, f), kaempferol diglycosides 1–4 (g, h), and isorhamnetin triglycoside (i, j) concentrations are shown, with error bars representing 1 SEM (n = 3 for undamaged leaves and n = 4 for damaged ones). p Values of one-way and two-way ANOVAs are shown (G: genotype, H: hervibory). In f, g, h, and j, different letters indicate differences within the genotype factor (Tukey test, p value < 0.05)

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This study demonstrates that soybean cultivars respond differentially to damage in a herbivore-specific manner, and trigger responses decreasing herbivore performance. Soybean crops are affected by a great number of insect herbivores, resulting in devastating yield losses. Secondary metabolites like proteinase inhibitors and phenolic compounds are...

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... 29 The low number of studies performed in natural conditions called our attention because it is known that variable natural conditions, such as solar ultraviolet radiation, desiccation and/or temperature range can influence plant-bacteria and plant-insect interactions. [30][31][32] Experiments in laboratory conditions to study plant-insectmicrobe interactions can be far away from reality. 33 Laboratory rearing conditions can alter symbiotic interactions between insects and some bacteria through contamination from food source or alterations of gut consortia diversity. ...
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Background: The southern green stinkbug (Nezara viridula) is a mayor pest of soybean. However, the mechanism underlying stinkbug resistance to soybean defenses is yet ignored. Although gut bacteria could play an essential role in tolerating plant defenses, most studies testing questions related to insect-plant-bacteria interactions have been performed in laboratory condition. Here we performed experiments in laboratory and field conditions with N.viridula and its gut bacteria, studying gut lipid peroxidaxion levels and cysteine activity in infected and unifected nymphs, testing the hypothesis that feeding on field-grown soybean decreases bacterial abundance in stinkbugs. Results: Gut bacterial abundance and infection ratio were higher in N.viridula adults reared in laboratory than in those collected from soybean crops, suggesting that stinkbugs in field conditions may modulate gut bacterial colonization. Manipulating gut microbiota by infecting stinkbugs with Yokenella sp. showed that these bacteria abundance decreased in field conditions, and negatively affected stinkbugs performance and were more aggressive in laboratory rearing than in field conditions. Infected nymphs that fed on soybean pods had lower mortality, higher mass and shorter development period than those reared in the laboratory, and suggested that field conditions helped nymphs to recover from Yokenella sp. infection, despite of increased lipid peroxidation and decreased cysteine proteases activity in nymphs' guts. Conclusions: Our results demonstrated that feeding on field-grown soybean reduced bacterial abundance and infection in guts of N.viridula and highlighted the importance to test functional activities or pathogenicity of microbes under realistic field conditions prior to establish conclusions on three trophic interactions. This article is protected by copyright. All rights reserved.
... In polyphagous insects, we can additionally examine aspects associated with the acceptance and/or rejection of plant species and what sets the limit of such differences between them. Often, these matters are addressed and treated as either a practical problem, in which case the plants of interest are generally domesticated plant species, typically referred to as 'crops' (Prager et al. 2014a, Romero et al. 2019 or as an ecological question, in which case the plant-insect pairing may not involve any domesticated plant species at all. However, domesticated plant species are often bred for traits other than insect resistance, while wild plant species may have been under severe selection leading to the evolution of traits that protect them from herbivory (Whitehead et al. 2017). ...
Article
Polyphagous insects are characterized by a broad diet comprising plant species from different taxonomic groups. Within these insects, migratory species are of particular interest, given that they encounter unpredictable environments, with abrupt spatial and temporal changes in plant availability and density. Aster leafhoppers (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) arrive in the Canadian Prairies in spring and early summer and are the main vector of a prokaryotic plant pathogen known as Aster Yellows Phytoplasma (AYp) (Candidatus Phytoplasma asteris). Host choice selection behavior of Aster leafhoppers was evaluated through two-choice bioassays, using domesticated and wild plants species commonly found in the Canadian Prairies. Leaf tissues from these plants were collected and stained to quantify the number of stylet sheaths and eggs. To assess possible effects due to insect infection, two-choice bioassays were repeated using leafhoppers infected with AYp and a subset of plant species. When two domesticated or wild plant species were presented together, similar numbers of uninfected Aster leafhoppers were observed on both plant species in most combinations. In domesticated-wild plant bioassays, uninfected Aster leafhoppers preferred to settle on the domesticated species. There was little to no association between settling preferences and stylet sheath and egg counts. These findings provide a better understanding of AY epidemiology and suggest that after domesticated species germination, leafhoppers could move from nearby wild plants into the preferred cereals (Poales: Poaceae) to settle on them, influencing the risk of AYp infection in some of these species.
... The biological activity of KTIs has been demonstrated by using gut extracts in in vitro assays [16,29], as well as monitoring the fitness of herbivores feeding on KTI-enriched diets [2,6,22,25,26,30]. Since the first description of a KTI in soybean [19,24], most subsequent studies have also focused on KTIs from legume species [16,17,22,30,36,43]. However, KTIs in trees have gained more attention in past years. ...
... Species-specificity has been reported for the induction of PIs in other systems, though not in poplar trees. In soybean, damage by fall armyworm caterpillars increased the activity of PIs, whereas thrips damage did not [43]. De Oliveira et al. [11] even observed varying response of tomato PIs to damage by herbivores of the same genus. ...
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Background Protease inhibitors are defense proteins widely distributed in the plant kingdom. By reducing the activity of digestive enzymes in insect guts, they reduce the availability of nutrients and thus impair the growth and development of the attacking herbivore. One well-characterized class of protease inhibitors are Kunitz-type trypsin inhibitors (KTIs), which have been described in various plant species, including Populus spp . Long-lived woody perennials like poplar trees encounter a huge diversity of herbivores, but the specificity of tree defenses towards different herbivore species is hardly studied. We therefore aimed to investigate the induction of KTIs in black poplar ( P. nigra ) leaves upon herbivory by three different chewing herbivores, Lymantria dispar and Amata mogadorensis caterpillars, and Phratora vulgatissima beetles. Results We identified and generated full-length cDNA sequences of 17 KTIs that are upregulated upon herbivory in black poplar leaves, and analyzed the expression patterns of the eight most up-regulated KTI s via qRT-PCR. We found that beetles elicited higher transcriptional induction of KTI s than caterpillars, and that both caterpillar species induced similar KTI expression levels. Furthermore, KTI expression strongly correlated with the trypsin-inhibiting activity in the herbivore-damaged leaves, but was not dependent on damage severity, i.e. leaf area loss, for most of the genes. Conclusions We conclude that the induction of KTIs in black poplar is controlled at the transcriptional level in a threshold-based manner and is strongly influenced by the species identity of the herbivore. However, the underlying molecular mechanisms and ecological consequences of these patterns remain to be investigated.
... Over the past decades, great effort has been devoted developing plant varieties with resistance to viruses although, resistance to thrips feeding is recently gaining attention [4 ,5]. Empirical approaches to HPR often involves phenotypic screening, that is, evaluation of germplasm for resistant genotypes [6][7][8][9][10][11][12][13][14]. Advances in phenotyping technologies support high-throughput characterization of crop resistance to thrips [8,15]. ...
... HPR results from a complex set of interdependent mechanisms ( Figure 1) ranging from morphological barriers to the complex array of signaling molecules of the plant's immune system. These plant-defensive responses are associated with constitutive, thus always present traits, or induced plant traits shaped upon attack or elicitation in the plant's morphology, physiology and/or chemistry producing plant secondary metabolites [13,22]. Both ways are not mutually exclusive and lead to direct or indirect effects through attraction of natural enemies. ...
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Integrated Pest Management (IPM) is endorsed as the future standard for crop protection worldwide. This holistic concept integrates preventative and curative measures amongst which host plant resistance (HPR) plays an essential role. Up to now HPR has been a somewhat under-utilized tool in pest management due to widespread use of pesticides and technological hindrance. Thrips are key pests in agriculture and horticulture worldwide. Here we provide an overview on the current status of research on constitutive and induced HPR including thrips–host relationships and thrips as virus vectors. We stress modulation of plant defense responses by abiotic and biotic elicitors to increase HPR and provide an outlook on the increasing potential of HPR inspired by the fast advancement of –omics techniques.
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The southern green stink bug, Nezara viridula is one of the primary soybean pests and causes significant economic losses around the world. In spite of the high proteases inhibitor (PI) levels, N. viridula can feed on developing seeds of field-grown soybean and reduce crop yields. Although the PI-induced responses have been extensively investigated in many pest insects, there is lack of knowledge about the mechanisms that stink bugs employ to withstand cysteine PIs of soybean seeds. This study demonstrated that feeding on developing seeds of field-grown soybean inhibited total proteases activity of N. viridula, as result of inhibition of cathepsin B-like activity in the gut. In addition, from the 30 digestive cathepsins recognized in this study, 6 were identified as cathepsin B-like. Stink bugs that fed on growing seeds of field-grown soybean had similar gut pH to those reared in the laboratory, and both cathepsin B- and L-like had an optima pH of 6.5. Therefore, using specific proteases inhibitors we found that the main proteolytic activity in the gut is from cysteine proteases when N. viridula feeds on soybean crops. Since cathepsin L-like activity was not inhibited by soybean PIs, our results suggested that N. viridula relays on cathepsin L-like to feed on soybean. To our knowledge no study before has shown the impact of seed PIs of field-grown soybean on digestive proteases (cathepsin B- and L-like) of N. viridula. This study suggests that the activity of PI-insensitive cathepsins L-like in the gut would be part of an adaptive strategy to feed on developing soybean seeds. In agreement, the expansions of cathepsin L-like complement observed in pentatomids could confer to the insects a higher versatility to counteract the effects of different PIs.