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1.
Planta ; 254(5): 101, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34669050

RESUMO

MAIN CONCLUSION: Increased resistance to insect herbivory in grain amaranth plants is associated with increased betalain pigmentation, either naturally acquired or accumulated in response to blue-red light irradiation. Betalains are water-soluble pigments characteristic of plants of the Caryophyllales order. Their abiotic stress-induced accumulation is believed to protect against oxidative damage, while their defensive function against biotic aggressors is scarce. A previous observation of induced betalain-biosynthetic gene expression in stressed grain amaranth plants led to the proposal that these pigments play a defensive role against insect herbivory. This study provided further support for this premise. First, a comparison of "green" and "red" Amaranthus cruentus phenotypes showed that the latter suffered less insect herbivory damage. Coincidentally, growth and vitality of Manduca sexta larvae were more severely affected when fed on red-leafed A. cruentus plants or on an artificial diet supplemented with red-leaf pigment extracts. Second, the exposure of A. cruentus and A. caudatus plants, having contrasting pigmentation phenotypes, to light enriched in the blue and red wavelength spectra led to pigment accumulation throughout the plant and to increased resistance to insect herbivory. These events were accompanied by the induced expression of known betalain-biosynthetic genes, including uncharacterized DODA genes believed to participate in this biosynthetic pathway in a still undefined way. Finally, transient co-expression of different combinations of betalain-biosynthetic genes in Nicotiana benthamiana led to detectable accumulation of betalamic acid and betanidin. This outcome supported the participation of certain AhDODA and other genes in the grain amaranth betalain-biosynthetic pathway.


Assuntos
Caryophyllales , Herbivoria , Animais , Insetos , Pigmentação , Tabaco
2.
J Agric Food Chem ; 69(38): 11204-11215, 2021 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-34544239

RESUMO

Herbivore-induced plant volatiles (HIPVs) play an important role in insect resistance. As a common HIPV in tea plants (Camellia sinensis), ß-ocimene has shown anti-insect function in other plants. However, whether ß-ocimene in tea plants also provides insect resistance, and its mechanism of synthesis and emission are unknown. In this study, ß-ocimene was confirmed to interfere with tea geometrid growth via signaling. Light was identified as the key factor controlling regular emission of ß-ocimene induced by the wounding from tea geometrids. ß-Ocimene synthase (CsBOS1) was located in plastids and catalyzed ß-ocimene formation in overexpressed tobacco. CsBOS1 expression in tea leaves attacked by tea geometrids showed a day-low and night-high variation pattern, while CsABCG expression involved in volatile emission showed the opposite pattern. These two genes might regulate the regular ß-ocimene emission from tea plants induced by tea geometrid attack. This study advances the understanding on HIPV emission and signaling in tea plants.


Assuntos
Camellia sinensis , Monoterpenos Acíclicos , Alcenos , Animais , Herbivoria , Insetos , Folhas de Planta , Chá
3.
BMC Plant Biol ; 21(1): 436, 2021 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-34563114

RESUMO

BACKGROUND: Nitrogen, as a limiting factor for net primary productivity in grassland ecosystems, is an important link in material cycles in grassland ecosystems. However, the nitrogen assimilation efficiency and mechanisms of grassland plants under grazing disturbance are still unclear. This study investigated Stipa breviflora desert steppe which had been grazed for 17 years and sampled the root system and leaf of the constructive species Stipa breviflora during the peak growing season under no grazing, light grazing, moderate grazing and heavy grazing treatments. The activities of enzymes related to nitrogen assimilation in roots and leaves were measured. RESULTS: Compared with no grazing, light grazing and moderate grazing significantly increased the activities of nitrate reductase (NR), glutamine synthetase (GS), glutamic oxaloacetic transaminase (GOT) and glutamic pyruvate transaminase (GPT) in leaves, and GS, GOT and GPT in roots of Stipa breviflora, while heavy grazing significantly decreased the activities of GS in leaves and NR in roots of Stipa breviflora. NR, GOT and GPT activities in leaves and roots of Stipa breviflora were positively correlated with nitrogen content, soluble protein, free amino acid and nitrate content. CONCLUSIONS: Grazing disturbance changed the activities of nitrogen assimilation related enzymes of grassland plants, and emphasized that light grazing and moderate grazing were beneficial for nitrogen assimilation by grassland plants. Therefore, establishing appropriate stocking rates is of great significance for material flows in this grassland ecosystem and for the stability and sustainable utilization of grassland resources.


Assuntos
Ativação Enzimática/fisiologia , Pradaria , Herbivoria , Nitrogênio/metabolismo , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Poaceae/metabolismo , Alanina Transaminase/metabolismo , Aspartato Aminotransferases/metabolismo , China , Glutamato-Amônia Ligase/metabolismo , Nitrato Redutase/metabolismo
4.
BMC Plant Biol ; 21(1): 402, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34470613

RESUMO

BACKGROUND: Plant-parasitic nematodes and herbivorous insects have a significant negative impact on global crop production. A successful approach to protect crops from these pests is the in planta expression of nematotoxic or entomotoxic proteins such as crystal proteins from Bacillus thuringiensis (Bt) or plant lectins. However, the efficacy of this approach is threatened by emergence of resistance in nematode and insect populations to these proteins. To solve this problem, novel nematotoxic and entomotoxic proteins are needed. During the last two decades, several cytoplasmic lectins from mushrooms with nematicidal and insecticidal activity have been characterized. In this study, we tested the potential of Marasmius oreades agglutinin (MOA) to furnish Arabidopsis plants with resistance towards three economically important crop pests: the two plant-parasitic nematodes Heterodera schachtii and Meloidogyne incognita and the herbivorous diamondback moth Plutella xylostella. RESULTS: The expression of MOA does not affect plant growth under axenic conditions which is an essential parameter in the engineering of genetically modified crops. The transgenic Arabidopsis lines showed nearly complete resistance to H. schachtii, in that the number of female and male nematodes per cm root was reduced by 86-91 % and 43-93 % compared to WT, respectively. M. incognita proved to be less susceptible to the MOA protein in that 18-25 % and 26-35 % less galls and nematode egg masses, respectively, were observed in the transgenic lines. Larvae of the herbivorous P. xylostella foraging on MOA-expression lines showed a lower relative mass gain (22-38 %) and survival rate (15-24 %) than those feeding on WT plants. CONCLUSIONS: The results of our in planta experiments reveal a robust nematicidal and insecticidal activity of the fungal lectin MOA against important agricultural pests which may be exploited for crop protection.


Assuntos
Aglutininas/farmacologia , Arabidopsis/parasitologia , Herbivoria , Marasmius/química , Nematoides/fisiologia , Aglutininas/química , Animais , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Mariposas/fisiologia , Doenças das Plantas/prevenção & controle , Plantas Geneticamente Modificadas
5.
Planta ; 254(4): 70, 2021 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-34499214

RESUMO

MAIN CONCLUSION: With domestication, northward spread, and breeding, maize defence against root-herbivores relied on induced defences, decreasing levels of phytohormones involved in resistance, and increasing levels of a phytohormone involved in tolerance. We addressed whether a suite of maize (Zea mays mays) phytohormones and metabolites involved in herbivore defence were mediated by three successive processes: domestication, spread to North America, and modern breeding. With those processes, and following theoretical predictions, we expected to find: a change in defence strategy from reliance on induced defences to reliance on constitutive defences; decreasing levels of phytohormones involved in herbivore resistance, and; increasing levels of a phytohormone involved in herbivore tolerance. We tested those predictions by comparing phytohormone levels in seedlings exposed to root herbivory by Diabrotica virgifera virgifera among four plant types encompassing those processes: the maize ancestor Balsas teosinte (Zea mays parviglumis), Mexican maize landraces, USA maize landraces, and USA inbred maize cultivars. With domestication, maize transitioned from reliance on induced defences in teosinte to reliance on constitutive defences in maize, as predicted. One subset of metabolites putatively involved in herbivory defence (13-oxylipins) was suppressed with domestication, as predicted, though another was enhanced (9-oxylipins), and both were variably affected by spread and breeding. A phytohormone (indole-3-acetic acid) involved in tolerance was enhanced with domestication, and with spread and breeding, as predicted. These changes are consistent with documented changes in herbivory resistance and tolerance, and occurred coincidentally with cultivation in increasingly resource-rich environments, i.e., from wild to highly enriched agricultural environments. We concluded that herbivore defence evolution in crops may be mediated by processes spanning thousands of generations, e.g., domestication and spread, as well as by processes spanning tens of generations, e.g., breeding and agricultural intensification.


Assuntos
Herbivoria , Zea mays , Domesticação , Oxilipinas , Melhoramento Vegetal , Zea mays/genética
6.
J Agric Food Chem ; 69(34): 9743-9753, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34465092

RESUMO

Indirect defense is an important strategy employed by sessile plants to defend against herbivorous insects by recruiting the natural enemies of herbivores mediated by herbivore-induced plant volatiles (HIPVs). We aimed to determine whether indirect defense occurs in Compositae with Chrysanthemum morifolium as the model and elucidate the mechanisms underlying the biosynthesis of HIPVs. Using two-choice olfactometer bioassays, we showed that C. morifolium plants following infestation by larvae of the tobacco cutworm (Spodoptera litura, TCW) were significantly more attractive to two natural enemies of TCW larvae than control plants, indicating that indirect defense is an active defense strategy of C. morifolium. The chemical cue responsible for indirect defense in C. morifolium was identified as a complex blend of volatiles predominated by sesquiterpenes and monoterpenes. A total of 11 candidate terpene synthase (TPS) genes were identified by comparing the transcriptomes of healthy and TCW-infested plants. Gene expression analysis confirmed that up-regulated CmjTPS genes are consistent with the elevated emission of terpenes after herbivory treatment. Our study showed that the herbivore-induced emission of JA-dependent volatile terpenes attracted both predatory and parasitic enemies of herbivores. Generally, our findings indicate that indirect defense might be an important defense mechanism against insects in C. morifolium.


Assuntos
Chrysanthemum , Herbivoria , Animais , Chrysanthemum/genética , Larva , Spodoptera/genética , Terpenos
7.
New Phytol ; 232(3): 1414-1423, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34379798

RESUMO

Insect fluid-feeding on fossil vascular plants is an inconspicuous and underappreciated mode of herbivory that can provide novel data on the evolution of deep-time ecological associations and indicate the host-plant preferences of ancient insect herbivores. Previous fossil studies have documented piercing-and-sucking herbivory but often are unable to identify culprit insect taxa. One line of evidence are punctures and scale-insect impression marks made by piercing-and-sucking insects that occasionally provide clues to the systematic identities and relationships of particular insect herbivores. We report here the earliest occurrences of piercing and sucking on early angiosperms as evidenced by scale insect covers, impression marks, punctures and body fossils - notably a mealybug - from the Lower Cretaceous Rose Creek Flora of the Dakota Formation (c. 103 Ma), in southeastern Nebraska, USA. The mealybug, two other scale insect taxa, and several distinctive damage types on laurel leaves and seed-plant stems at Rose Creek document a diverse guild of piercing-and-sucking insects on early angiosperms. The discovery of an Early Cretaceous female mealybug indicates an early herbivorous association with a laurel host. These data provide direct evidence for co-associations and possible coevolution of scale insects and their plant hosts during early angiosperm diversification.


Assuntos
Hemípteros , Magnoliopsida , Animais , Evolução Biológica , Fósseis , Herbivoria , Insetos
8.
Mar Environ Res ; 170: 105435, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34385137

RESUMO

Sargassum horneri, a brown macroalga, recently invaded the California coast, including into critical foundational communities such as kelp (Macrocystis pyrifera) forests. Despite its rapid spread, empirical tests that evaluate mechanisms underlying S. horneri's invasion success are lacking. To fill this knowledge gap, we conducted three field experiments on temperate rocky reefs in southern California using growth as a proxy for invasion success. We first tested whether S. horneri success differed with herbivory strength and native diversity by conducting a 2-factor experiment varying site (with different baseline levels of urchin densities and native algal diversity) and urchin access. We found S. horneri growth only differed among urchin treatments and not sites. We then evaluated whether S. horneri could successfully invade established algal canopies as a driver or whether it required open space as a passenger via a 2-factor experiment varying S. horneri size (small, medium, large) and canopy type (S. horneri, kelp, -canopy). We found that all S. horneri sizes grew fastest when canopy was lacking and light was high and slower in both canopy habitats with lower light; overall, small S. horneri grew slowest. Finally, we evaluated whether herbivore consumption for native species could facilitate S. horneri's invasion by conducting a 2-factor experiment varying species (M. pyrifera, S. horneri) and herbivore access. We found uncaged algae were consumed and caged algae grew, but there was no difference between species. Taken together, our results suggest that S. horneri is a "passenger" invader that will take advantage of points in time and space where light is plentiful, such as when M. pyrifera is removed via disturbance. Further, our results suggest that herbivory and native algal diversity are likely not key determining factors of the invasion success of S. horneri.


Assuntos
Kelp , Macrocystis , Ecossistema , Florestas , Herbivoria
9.
J Environ Manage ; 298: 113554, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34426220

RESUMO

Carpobrotus edulis is an invasive clonal plant with drastic effects on biodiversity and functioning of coastal ecosystems. In recent years, authorities and land managers have implemented diverse management strategies that usually focus on mechanical removal and chemical control. However, applying mechanical control to remove C. edulis may cause indirect adverse effects since it could increase the probability of spreading new propagules, which do not lose their physiological activity. Therefore, reducing the physiological activity of these plant fragments should be a priority to avoid their spread and re-rooting. Our goal was to assess the plant regeneration capacity after applying mechanical control (i) when placing the plant material on different types of ground surface (on sand, on stones and using rooted plants as control) and (ii) combined with the attack of specialized herbivores (the soft scale Pulvinariella mesembryanthemi). To achieve this, we evaluated how these two factors (ground surface and herbivory) affected the plant physiological activity, its survival and re-rooting, biometric measurements, shoot and root nutrient composition and biochemical parameters (total phenols and tannins). Regardless of the ground surface type, our results indicated that the specialist herbivore greatly affected the C. edulis parameters studied. The attack of P. mesembryanthemi stimulated the plant defence mechanisms, even in those individuals with less photosynthetic activity. Furthermore, P. mesembryanthemi severely reduced the biomass and volume of plant material. Decomposition of C. edulis was accelerated by the combination between the inoculation of P. mesembryanthemi and placing the plants on the stones ground surface. Overall, preventing plant re-rooting by avoiding connection to the soil is an effective method of reducing its viability after the eighth-tenth month. After applying mechanical control, we recommend placing C. edulis fragments over an inert ground surface to avoid re-rooting, which would favour its death. We conclude that the combination of mechanical control and P. mesembryanthemi or even direct inoculation with this specialist herbivore could help authorities and land managers to improve management strategies for C. edulis.


Assuntos
Aizoaceae , Ecossistema , Herbivoria , Humanos , Plantas , Solo
10.
J Chem Ecol ; 47(8-9): 799-809, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34347233

RESUMO

Fall armyworm (Spodoptera frugiperda) is a major global pest of many crops, including maize (Zea mays). This insect is known to use host plant-derived volatile organic compounds to locate suitable hosts during both its adult and larval stages, yet the function of individual compounds remains mostly enigmatic. In this study, we use a combination of volatile profiling, electrophysiological assays, pair-wise choice behavioral assays, and chemical supplementation treatments to identify and assess specific compounds from maize that influence S. frugiperda host location. Our findings reveal that methyl salicylate and (E)-alpha-bergamotene are oviposition attractants for adult moths but do not impact larval behavior. While geranyl acetate can act as an oviposition attractant or repellent depending on the host volatile context and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) is an oviposition deterrent. These compounds can also be attractive to the larvae when applied to specific maize inbreds. These data show that S. frugiperda uses different plant volatile cues for host location in its adult and larval stage and that the background volatile context that specific volatiles are perceived in, alters their impact as behavioral cues.


Assuntos
Herbivoria/efeitos dos fármacos , Oviposição/efeitos dos fármacos , Spodoptera/fisiologia , Compostos Orgânicos Voláteis/farmacologia , Zea mays/química , Animais , Compostos Bicíclicos com Pontes/isolamento & purificação , Compostos Bicíclicos com Pontes/farmacologia , Cromatografia Gasosa-Espectrometria de Massas , Larva/fisiologia , Folhas de Planta/química , Folhas de Planta/metabolismo , Análise de Componente Principal , Salicilatos/isolamento & purificação , Salicilatos/farmacologia , Spodoptera/crescimento & desenvolvimento , Terpenos/isolamento & purificação , Terpenos/farmacologia , Compostos Orgânicos Voláteis/química , Zea mays/metabolismo
11.
Ecol Lett ; 24(11): 2439-2451, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34418263

RESUMO

Foraging trails of leafcutter colonies are iconic scenes in the Neotropics, with ants collecting freshly cut plant fragments to provision a fungal food crop. We hypothesised that the fungus-cultivar's requirements for macronutrients and minerals govern the foraging niche breadth of Atta colombica leafcutter ants. Analyses of plant fragments carried by foragers showed how nutrients from fruits, flowers and leaves combine to maximise cultivar performance. While the most commonly foraged leaves delivered excess protein relative to the cultivar's needs, in vitro experiments showed that the minerals P, Al and Fe may expand the leafcutter foraging niche by enhancing the cultivar's tolerance to protein-biased substrates. A suite of other minerals reduces cultivar performance in ways that may render plant fragments with optimal macronutrient blends unsuitable for provisioning. Our approach highlights how the nutritional challenges of provisioning a mutualist can govern the multidimensional realised niche available to a generalist insect herbivore.


Assuntos
Formigas , Animais , Fungos , Herbivoria , Folhas de Planta , Simbiose
12.
Int J Mol Sci ; 22(15)2021 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-34360628

RESUMO

Macroalgae are the source of many harmful allelopathic compounds, which are synthesized as a defense strategy against competitors and herbivores. Therefore, it can be predicted that certain species reduce aquaculture performance. Herein, the allelopathic ability of 123 different taxa of green, red, and brown algae have been summarized based on literature reports. Research on macroalgae and their allelopathic effects on other animal organisms was conducted primarily in Australia, Mexico, and the United States. Nevertheless, there are also several scientific reports in this field from South America and Asia; the study areas in the latter continents coincide with areas where aquaculture is highly developed and widely practiced. Therefore, the allelopathic activity of macroalgae on coexisting animals is an issue that is worth careful investigation. In this work, we characterize the distribution of allelopathic macroalgae and compare them with aquaculture locations, describe the methods for the study of macroalgal allelopathy, present the taxonomic position of allelopathic macroalgae and their impact on coexisting aquatic competitors (Cnidaria) and herbivores (Annelida, Echinodermata, Arthropoda, Mollusca, and Chordata), and compile information on allelopathic compounds produced by different macroalgae species. This work gathers the current knowledge on the phenomenon of macroalgal allelopathy and their allelochemicals affecting aquatic animal (competitors and predators) worldwide and it provides future research directions for this topic.


Assuntos
Alelopatia , Aquicultura , Invertebrados , Defesa das Plantas contra Herbivoria , Alga Marinha/metabolismo , Animais , Herbivoria , Alga Marinha/genética
13.
Oecologia ; 197(1): 243-257, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34370096

RESUMO

The diversity of endotherms and ectotherms may be differently affected by ambient temperature and net primary productivity (NPP). Additionally, little is known about how these drivers affect the diversity of guilds of different trophic levels. We assessed the relative role of temperature and NPP in multitrophic guilds of ectothermic (arthropods: ants, ground beetles, spiders, and harvestmen) and endothermic (large mammals) animals along a tropical elevational gradient. We sampled arthropods at eight elevation belts and large mammals at 14 elevation belts in Atlantic rainforest (ranging from 600 to 2450 m.a.s.l.) of Itatiaia National Park, Southeast Brazil. Overall arthropod species richness was more associated with temperature than overall large-mammal species richness, while the latter was more associated with NPP. When separated into trophic guilds, we found that the species richness associated with NPP increased across arthropod trophic levels from herbivores to predators. Conversely, although NPP influenced large-mammal herbivore species richness, its effects did not seem to accumulate across large-mammal trophic levels since the species richness of large-mammal omnivores was more associated with temperature and none of the variables we studied influenced large-mammal predators. We suggest that thermal physiological differences between ectotherms and endotherms are responsible for the way in which arthropods and large mammals interact with or are constrained by the environment. Furthermore, the inconsistency regarding the role of temperature and NPP on species richness across multitrophic guilds of ectotherms and endotherms could indicate that thermal physiological differences might also interfere with energy use and flux in the food web.


Assuntos
Artrópodes , Biodiversidade , Animais , Ecossistema , Herbivoria , Temperatura
14.
BMC Plant Biol ; 21(1): 401, 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-34461825

RESUMO

BACKGROUND: Timing is everything when it comes to the fitness outcome of a plant's ecological interactions, and accurate timing is particularly relevant for interactions with herbivores or mutualists that are based on ephemeral emissions of volatile organic compounds. Previous studies of the wild tobacco N. attenuata have found associations between the diurnal timing of volatile emissions, and daytime predation of herbivores by their natural enemies. RESULTS: Here, we investigated the role of light in regulating two biosynthetic groups of volatiles, terpenoids and green leaf volatiles (GLVs), which dominate the herbivore-induced bouquet of N. attenuata. Light deprivation strongly suppressed terpenoid emissions while enhancing GLV emissions, albeit with a time lag. Silencing the expression of photoreceptor genes did not alter terpenoid emission rhythms, but silencing expression of the phytochrome gene, NaPhyB1, disordered the emission of the GLV (Z)-3-hexenyl acetate. External abscisic acid (ABA) treatments increased stomatal resistance, but did not truncate the emission of terpenoid volatiles (recovered in the headspace). However, ABA treatment enhanced GLV emissions and leaf internal pools (recovered from tissue), and reduced internal linalool pools. In contrast to the pattern of diurnal terpenoid emissions and nocturnal GLV emissions, transcripts of herbivore-induced plant volatile (HIPV) biosynthetic genes peaked during the day. The promotor regions of these genes were populated with various cis-acting regulatory elements involved in light-, stress-, phytohormone- and circadian regulation. CONCLUSIONS: This research provides insights into the complexity of the mechanisms involved in the regulation of HIPV bouquets, a mechanistic complexity which rivals the functional complexity of HIPVs, which includes repelling herbivores, calling for body guards, and attracting pollinators.


Assuntos
Ritmo Circadiano , Herbivoria/fisiologia , Luz , Tabaco/fisiologia , Compostos Orgânicos Voláteis/metabolismo , Ácido Abscísico/farmacologia , Animais , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/fisiologia , Larva/fisiologia , Mariposas/fisiologia , Fitocromo B/genética , Fitocromo B/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Terpenos/metabolismo
15.
Biol Lett ; 17(8): 20210175, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34343435

RESUMO

The consequences of climate change for biogeographic range dynamics depend on the spatial scales at which climate influences focal species directly and indirectly via biotic interactions. An overlooked question concerns the extent to which microclimates modify specialist biotic interactions, with emergent properties for communities and range dynamics. Here, we use an in-field experiment to assess egg-laying behaviour of a range-expanding herbivore across a range of natural microclimatic conditions. We show that variation in microclimate, resource condition and individual fecundity can generate differences in egg-laying rates of almost two orders of magnitude in an exemplar species, the brown argus butterfly (Aricia agestis). This within-site variation in fecundity dwarfs variation resulting from differences in average ambient temperatures among populations. Although higher temperatures did not reduce female selection for host plants in good condition, the thermal sensitivities of egg-laying behaviours have the potential to accelerate climate-driven range expansion by increasing egg-laying encounters with novel hosts in increasingly suitable microclimates. Understanding the sensitivity of specialist biotic interactions to microclimatic variation is, therefore, critical to predict the outcomes of climate change across species' geographical ranges, and the resilience of ecological communities.


Assuntos
Borboletas , Microclima , Animais , Mudança Climática , Ecossistema , Feminino , Herbivoria , Plantas , Temperatura
16.
An Acad Bras Cienc ; 93(3): e20191456, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34378641

RESUMO

The spittlebugs Mahanarva spectabilis economically challenges cattle production of neotropical regions, due to its voracious feeding on tropical grasses. Here, we evaluated biochemical responses of the interaction between M. spectabilis and the widely cultivated tropical grasses Brachiaria spp. (i.e., brizantha and decumbens) and elephant grasses (cvs. Roxo de Botucatu and Pioneiro), regarding lipoxygenases, protease inhibitors, phytohormones, and proteolytic activities in the midgut of M. spectabilis. The M. spectabilis-infested grasses increased lipoxygenases activity, except for cv. Pioneiro. The levels of the phytohormones jasmonic and abscisic acids were similarly low in all genotypes and increased under herbivory. Furthermore, salicylic acid concentration was constitutively higher in Brachiaria sp., increasing only in spittlebug-infested B. decumbens. M. spectabilis infestations did not induce increases of protease inhibitors in any forage grass type. The trypsin activity remained unaltered, and the total proteolytic activity increased only in B. decumbens-fed insects. Our findings revealed that most forage grasses exposed to spittlebugs activate the lipoxygenases pathway, resulting in increased abscisic and jasmonic acids. However, greater amounts of these hormones do not induce protease inhibitory activity in response to spittlebug attack. This knowledge certainly helps to guide future projects aiming at reducing the impact of spittlebugs on forage production.


Assuntos
Brachiaria , Hemípteros , Pennisetum , Animais , Bovinos , Genótipo , Herbivoria
17.
Nat Commun ; 12(1): 4716, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-34354058

RESUMO

Habitat fragmentation and eutrophication have strong impacts on biodiversity. Metacommunity research demonstrated that reduction in landscape connectivity may cause biodiversity loss in fragmented landscapes. Food-web research addressed how eutrophication can cause local biodiversity declines. However, there is very limited understanding of their cumulative impacts as they could amplify or cancel each other. Our simulations of meta-food-webs show that dispersal and trophic processes interact through two complementary mechanisms. First, the 'rescue effect' maintains local biodiversity by rapid recolonization after a local crash in population densities. Second, the 'drainage effect' stabilizes biodiversity by preventing overshooting of population densities on eutrophic patches. In complex food webs on large spatial networks of habitat patches, these effects yield systematically higher biodiversity in heterogeneous than in homogeneous landscapes. Our meta-food-web approach reveals a strong interaction between habitat fragmentation and eutrophication and provides a mechanistic explanation of how landscape heterogeneity promotes biodiversity.


Assuntos
Biodiversidade , Ecossistema , Cadeia Alimentar , Modelos Biológicos , Migração Animal , Animais , Simulação por Computador , Eutrofização , Herbivoria , Recursos Naturais , Plantas , Densidade Demográfica , Comportamento Predatório
18.
An Acad Bras Cienc ; 93(suppl 2): e20201594, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34406219

RESUMO

Uruguaysuchidae was a diverse group of crocodyliforms with widespread Gondwanan distribution. Recent phylogenies recover a clade comprising six species of Araripesuchus and one Uruguaysuchus. We reviewed the morphological variation in the dentition of uruguaysuchid specimens, including unpublished fossils from the Crato (SMNK PAL 6404) and Romualdo (MN 7061-V) formations of the Araripe Basin. Dental patterns are clearly distinct between species, with important taxonomic and possible ecological implications. Neither Araripesuchus nor Uruguaysuchus have characters suggesting exclusive herbivory, even for species in which tooth-tooth occlusion is observed. New data on A. gomesii shows differences in teeth number between the new specimen MN 7061-V and the holotype, probably due to preservation. The specimen SMNK PAL 6404 has a unique combination of dental characters, which reinforces the hypothesis that it might belong to a new Araripesuchus species. The alveoli pattern of A. rattoides is very distinctive in comparison to other araripesuchids, what also suggests different taxonomic affinities. One interpretation for the morphological variation in the dentition of Uruguaysuchidae is foraging specializations for different life habits. Niche partitioning and ecological specialization could have been an important process in explaining the high taxonomic diversity and widespread spatial distribution of these animals in the Cretaceous of Gondwana.


Assuntos
Dentição , Fósseis , Animais , Herbivoria , Filogenia
19.
Neotrop Entomol ; 50(4): 643-653, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34212314

RESUMO

Host plant resistance mechanisms play an important role in developing cultivars with resistance to the target pests; information regarding morphological and biochemical factors contributing to the resistance is essential for developing pest-resistant cultivars. As a result, we investigated the contribution of various morphological and biochemical characters in forty-two eggplant genotypes against Leucinodes orbonalis Guenée, in Himachal Pradesh, India. Out of all the phenotypic parameters evaluated, pericarp thickness (r = 0.89) has significantly positive correlation with fruit infestation, whereas trichome density had significantly negative correlation (r = - 0.89). Analysis of the biochemical compounds in the eggplant genotypes revealed that total phenols (r = - 0.71), polyphenol oxidase (r = - 0.63), peroxidases (r = - 0.35), phenylalanine ammonium lyase (r = - 0.71) and solasodine (r = - 0.81) had significantly negative correlation with the per cent fruit infestation by L. orbonalis while the reducing sugars (r = 0.66) and non-reducing sugars (r = 0.62) showed a significantly positive correlation. Molecular characterization by random amplified polymorphic DNA (RAPD) primers also revealed the presence of high genetic diversity among different eggplant genotypes, where 17 polymorphic RAPD primers produced a total of 167 amplicons, among which 144 amplicons were polymorphic and 23 monomorphic bands. PCR-amplified DNA fragment size ranged from 100 to 2500 bp, mean polymorphism was 86.42% and the average PIC value was 0.444. Jaccards coefficient-based dendrogram grouped 40 eggplant genotypes into two major clusters. Results also revealed that the resistant genotypes accumulated higher levels of defensive biochemical enzymes such as phenols, PO, PPO, PAL and solasodine to confer insect resistance. Molecular characterization also revealed that genotypes in the present study were genetically diverse and could be used in future breeding and improvement programmes in this crop. Genotypes, IC411485 and IC090951, in particular, can be used as varied parents in breeding programmes to generate improved lines in terms of resistance to L. orbonalis.


Assuntos
Mariposas , Solanum melongena , Animais , Frutas , Variação Genética , Genótipo , Herbivoria , Técnica de Amplificação ao Acaso de DNA Polimórfico , Solanum melongena/genética
20.
Pest Manag Sci ; 77(11): 5255-5267, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34310838

RESUMO

BACKGROUND: Biological control plays a key role in reducing crop damage by Tuta absoluta (Meyrick) and Trialeurodes vaporariorum (Westwood), which cause huge yield losses in tomato (Solanum lycopersicum L.). The mirid predator Nesidiocoris tenuis (Reuter) preys heavily on these pests, with satisfying control levels in tomato greenhouses. Although N. tenuis is known to be attracted to volatiles of tomato plants infested by T. absoluta and whitefly, little is known about the specific attractive compounds and the effect of prey density on the predator response. RESULTS: Y-tube olfactometer bioassays revealed that the attraction of N. tenuis to tomato volatiles was positively correlated with the density of T. absoluta infestation, unlike T. vaporariorum infestation. The predator was also attracted to volatiles of T. absoluta larval frass, but not to T. vaporariorum honeydew or T. absoluta sex pheromone. Among the herbivore-induced plant volatiles (HIPVs) that characterised the attractive plants infested with 20 T. absoluta larvae, olfactometer bioassays revealed that N. tenuis is attracted to the monoterpenes α-pinene, α-phellandrene, 3-carene, ß-phellandrene and ß-ocimene, whereas (E)-ß-caryophyllene was found to repel the predator. In dose-response bioassays, the five-component blend of the attractants elicited a relatively low attraction in the predator, and removal of ß-phellandrene from the blend enhanced the attraction of the predator to the resulting four-component blend, suggesting synergism among four monoterpenes. CONCLUSION: These findings suggest that a four-component blend of α-pinene, α-phellandrene, 3-carene and ß-ocimene could be used as a kairomone-based lure to recruit the predator for the biological control of T. absoluta and T. vaporariorum.


Assuntos
Hemípteros , Heterópteros , Lycopersicon esculentum , Compostos Orgânicos Voláteis , Animais , Herbivoria , Terpenos , Compostos Orgânicos Voláteis/farmacologia
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