Earthquakes induce ultimate load conditions in most earthquake resistant structures and often lead to complete failure and disposal. Seismic sustainability is a limit state condition with a view to ...revival, reuse, and environmental protection. In the present context, sustainable seismic design implies planning for controlled energy dissipation, sequential failures, collapse prevention, construction economy and post-earthquake realignment and repairs. However, regardless of savings and environmental improvements unless an earthquake resistant structure is designed for the purpose, it would be disposable with greater monetary loss and harm to the environment. It has been found that steel mixed multiple seismic systems are well-suited for sustainable seismic design. Mixed multiple structures are combinations of two or more low/controlled damage ductile structures, an articulated gravity frame, a collapse preventive, hybrid, rigid rocking core, and a phantom P-delta system acting together to form a repairable archetype. Each earthquake resistant system is equipped with replaceable energy dissipating and fail-safe devices. Such arrangements call for applications of Plastic Design and Performance Control principles, rather than conventional methods of approach. This in turn calls for development of modern design rules, technologies and details that govern the behavior of such systems equipped with replaceable energy dissipating devices. In the interim several observations that reduce the task of otherwise cumbersome analysis to simple rules of response have been introduced.
Microplastics are very common contaminants in the environment. Despite increasing efforts to assess the effects of microplastics on soil organisms, there remains a lack of knowledge on how organisms ...respond to diverse types of microplastics after different exposure durations. In the present study, we investigated the immune response of the terrestrial crustacean Porcellio scaber exposed to the two most common microplastic particles in the environment: polyester fibres and tyre particles. We also tested two natural particles: wood dust and silica powder, with all treatments performed at 1.5% w/w. The response of P. scaber was evaluated at the level of the immune system, and also the biochemical, organism and population level, after different exposure durations (1, 2, 4, 7, 14, 21 days). These data reveal dynamic changes in the levels of some immune parameters shortly after exposure, with a gradual return to control values. The total number of haemocytes was significantly decreased after 4 days of exposure to tyre particles, while the proportion of different haemocyte types in the haemolymph was altered shortly after exposure to both polyester fibres and tyre particles. Moreover, 7 days of exposure to tyre particles resulted in increased superoxide dismutase activity in the haemolymph, while metabolic activity in whole woodlice (measured as electron transport system activity) was increased after exposure for 7, 14 and 21 days. In contrast, the natural particles did not elicit any significant changes in the measured parameters. Survival and feeding of P. scaber were not altered by exposure to the microplastics and natural particles in soil. Overall, this study defines a time-dependent transient immune response of P. scaber, which indicates that immune parameters represent sensitive biomarkers of exposure to microplastics. We discuss the importance of using natural particles in studies of microplastics exposure and their effects.
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•We studied natural particles and microplastics for immune effects in Porcellio scaber•Haemocyte proportions in haemolymph rapidly and transiently changed for microplastics•Exposure to tyre particles significantly increased whole woodlouse metabolic activity•There were no changes in measured parameters for exposure to natural particles
Thymus vulgaris and Tagetes minuta essential oils (EOs) are recognized due to their antibacterial activity against Streptomyces scabiei, the main causal agent of potato common scab disease. However, ...EOs have phytotoxic characteristics and are susceptible to degradation by environmental factors, which make their storage and application difficult. Microencapsulation technology represents an alternative for EOs handle, allowing their protection and gradual spread of their compounds. In the present work, microcapsules of maltodextrin and hydroxypropyl methylcellulose containing T. minuta and T. vulgaris EOs were evaluated, analyzing their features, their stability at storage conditions and the control release of their volatile compounds when they are applied on humid substrate. Additionally, the in vitro antibacterial activity of microencapsulated EOs against S. scabiei, and their effects on potato crop yield were evaluated. The obtained microcapsules presented good yield (48.28–51.01 %), low moisture (3.87–3.98 %), spherical shape, and variable size. The release rate of volatiles was high and constant over the 29 days of storage, for almost every compound detected from microcapsules containing T. vulgaris EO. Additionally, the microcapsules containing T. minuta EO showed a variable but high release rate of its main compound dihydrotagetone. The application of microcapsules on humid substrate resulted in a greater release of volatiles for 14 days. The application of T. vulgaris and T. minuta EOs on potato plants (var. Spunta) showed no effect on plant growth and photosynthetic activity, but reduced tuber yield (9.07 and 9.40 g tubers fresh weight/ plant, respectively). The microencapsulation of these EOs reduced this effect (10.14 and 10.29 g tubers fresh weight/plant, respectively), and maintained the bacteriostatic activity on S. scabiei, making them a promising tool for potato common scab control.
Natural control of phytopathogenic microorganisms is assumed as a priority function of the commensal plant microbiota. In this study, the suitability of fluorescent pseudomonads in the phyllosphere ...of crop plants as natural control agents was evaluated. Under field conditions, ears of winter wheat were found to be colonized with high consistency and at a high density by pseudomonads at the late milk dough stage. Isolates of these bacteria were evaluated for their potential to protect the plants from phytopathogenic
and
fungi. More
isolates were antagonistically active against alternaria than against fusaria in the dual culture test. The alternaria responded species-specifically and more sensitively to bacterial antagonism than the strain-specific reacting fusaria. A total of 110 randomly selected
isolates were screened for genes involved in the biosynthesis of the antibiotics 2,4-diacetylphloroglucinol, phenazine-1-carboxylic acid, pyoluteorin, and pyrrolnitrin. The key gene for production of the phloroglucinol was found in none of these isolates. At least one of the genes, encoding the biosynthesis of the other antibiotics was detected in 81% of the isolates tested. However, the antagonistic effect found in the dual culture assay was not necessarily associated with the presence of these antibiotic genes. Wheat grains as natural substrate were inoculated with selected antagonistic
isolates and
and
strains, respectively. The fungal growth was only slightly delayed, but the mycotoxin production was significantly reduced in most of these approaches. In conclusion, the distribution of phytopathogenic fungi of the genera
and
in the field is unlikely to be inhibited by naturally occurring pseudomonads, also because the bacterial antagonists were not evenly distributed in the field. However, pseudomonads can reduce the production of
and
mycotoxins in wheat grains and thus have the potential to improve the crop quality.
•We review models of natural pest control assessing usability across agroecosystems.•Ecological complexity and context sensitivity impede correlation-based predictions.•A trade-off of generality with ...realism hinders mechanistic modeling across systems.•Similarities in causal relationships can inform contextually bound generalizations.•This framework will allow knowledge synthesis and transfer in less studied regions.
Natural control of invertebrate crop pests has the potential to complement or replace conventional insecticide-based practices, but its mainstream application is hampered by predictive unreliability across agroecosystems. Inconsistent responses of natural pest control to changes in landscape characteristics have been attributed to ecological complexity and system-specific conditions. Here, we review agroecological models and their potential to provide predictions of natural pest control across agricultural landscapes. Existing models have used a multitude of techniques to represent specific crop-pest-enemy systems at various spatiotemporal scales, but less wealthy regions of the world are underrepresented. A realistic representation of natural pest control across systems appears to be hindered by a practical trade-off between generality and realism. Nonetheless, observations of context-sensitive, trait-mediated responses of natural pest control to land-use gradients indicate the potential of ecological models that explicitly represent the underlying mechanisms. We conclude that modelling natural pest control across agroecosystems should exploit existing mechanistic techniques towards a framework of contextually bound generalizations. Observed similarities in causal relationships can inform the functional grouping of diverse agroecosystems worldwide and the development of the respective models based on general, but context-sensitive, ecological mechanisms. The combined use of qualitative and quantitative techniques should allow the flexible integration of empirical evidence and ecological theory for robust predictions of natural pest control across a wide range of agroecological contexts and levels of knowledge availability. We highlight challenges and promising directions towards developing such a general modelling framework.
ABSTRACT Fungi are the primary infectious agents in plants causing significant economic losses in agroindustry. Traditionally, these pathogens have been treated with different synthetic fungicides ...such as hydroxianilides, anilinopyrimidines, and azoles, to name a few. However, the indiscriminate use of these chemicals has increased fungi resistance in plants. Natural products have been researched as a control, and an alternative to these synthetic fungicides since they are not harmful to health and contribute to the environment caring. This review describes plants extracts, essential oils, and active compounds or secondary metabolites as antifungal agents both, in vitro and in vivo. Active compounds have been recently described as the best candidates for the control of phytopathogenic fungi. When metabolized by plants, these compounds concentrations rely on the environmental conditions and pathogens incidence. However, one issue regarding the direct application of these preformed compounds in plants touch upon their low persistence in the environment, and their even lower bioavailability than synthetic fungicides. Hence the challenge is to develop useful formulations based on natural products to increase the compounds solubility facilitating thus their application in the field while maintaining their properties.
Insecticide overuse in crop production systems often results in detrimental effects on predators and parasitoids, which regulate important insect pests. The natural enemies are also unable to survive ...in monocrop landscapes with the absence of shelter or food sources. Diversified vegetation, especially with flowering plants, can enhance natural enemy abundance and diversity, thus strengthening biological control, enabling farmers to reduce insecticides. In this study, we conserved bund vegetation and manipulated the existing rice landscapes with flowering plants to provide food and shelter for the biological control agents. Our study revealed significant positive relationships between predator densities and bund plant diversity. The abundance of predators significantly increased in the eco-engineered plots, especially at the flowering peaks compared to the insecticide-treated and control plots, while parasitoids were more diverse in both the eco-engineered and control plots. There were no significant differences in planthopper and leafhopper densities among the treatments during the rice early and maximum tillering stages, suggesting effective natural control of these herbivore pests in the eco-engineered plots at the early rice-growing season. However, at the heading stage relatively higher planthopper and leafhopper populations in the control and eco-engineered plots than in the insecticide-sprayed plots were recorded, suggesting perhaps the need for insecticide interventions if exceeding the threshold at this time. Our study indicates that manipulating the habitats surrounding the rice fields to enhance natural enemies is a sustainable practice in rice production as it can enhance the natural suppression of pests and thus reducing the need for insecticide.
Algunas especies de Pseudococcidae y Putoidae (Hemiptera: Coccomorpha), son plagas importantes de las raíces del café en varias partes del mundo, para su manejo el control biológico es una ...alternativa; por lo tanto, en ocho departamentos cafeteros de Colombia se realizó la búsqueda e identificación de enemigos naturales de cochinillas harinosas de las raíces del café. Se recolectaron y depositaron en alcohol muestras de pseudocóccidos y putoideos de 520 fincas, las cuales se limpiaron y se separaron por color y tamaño. Se encontraron 120 especímenes de enemigos naturales en 44 fincas parasitando cochinillas harinosas de las familias Putoidae y Pseudococcidae. Caldas presentó el mayor porcentaje de fincas con parasitoides con 15,3%, le sigue Antioquia con 14,1%, Cauca con 13,8%, Valle del Cauca con 10,4 %, Tolima con 4,2%, Risaralda con 3,8 % y por último Quindío con 1,2%. Posteriormente, se visitaron nuevamente 20 de los predios donde hubo parasitismo y se recolectaron individuos de cochinillas harinosas, las cuales se transportaron vivas al laboratorio. En las cámaras de cría de las cochinillas harinosas emergieron 28 avispas parasitoides adultas, i.e. Aenasius caeruleus Brues, 1910, Aenasius bolowi Mercet, 1947, Aenasius tachigaliae (Brues, 1922), Aenasius af. mitchellae Noyes and Ren, 1995, Zarhopalus putophilus Bennett, 1957, Hambletonia pseudococcina Compere, 1936, Hambletonia sp., Prochiloneurus af. dactylopii (Howard, 1885), Leptomastix sp., Cicoencyrtus sp. (Hymenoptera: Encyrtidae) y cinco adultos cecidómidos (Diptera: Cecidomyiidae). También se registraron dos especies de coccinélidos (Coleoptera: Coccinellidae) y un hongo antagonístico Trichoderma sp. De estos hallazgos puede concluirse que existen varias especies de enemigos naturales que están ejerciendo control natural en campo sobre las cochinillas harinosas que infestan las raíces del café. Se recomienda explorar una alternativa de control biológico por aumentación.
Abstract The sugarcane shoot borer ( Scirpophaga excerptalis ) is an herbivorous insect that primarily infests sugarcane plants, leading to the development of dead heart symptoms. This study aimed to ...investigate the contribution of egg parasitoids in mitigating the occurrence of dead heart caused by S. excerptalis infestation. The research was conducted in Asembagus and Malang, East Java, Indonesia. The samples collection of shoot borer eggs were done twice in Asembagus, and three times in Malang. The collected eggs were examined to determine the percentage of parasitism, and the emerged parasitoids were identified. The infestation level of shoot borers was evaluated by counting the dead heart symptoms within 5 m 2 observation units, comprising 18 and 15 units in Asembagus and Karangploso, respectively. Three species of parasitoids, namely Telenomus sp., Trichogramma chilonis , and Tetrastichus sp., were found to parasitize S. excerptalis eggs. The average parasitism levels by Telenomus sp., T. chilonis , and Tetrastichus sp. were 74% (ranged: 50-100%), 0.6% (ranged: 0-4.4%), and 14.3% (ranged: 0-100%), respectively. Telenomus sp. was the predominant egg parasitoid observed in all observations at both sites. There was an inverse relationship between the mortality of shoot borer eggs by parasitoids and the occurrence of dead heart symptoms. Higher levels of parasitism were associated with reduced dead shoot symptoms. The natural control of S. excerptalis through the complex of egg parasitoids holds a promise for effective management of sugarcane shoot borers and promoting sustainable agriculture.
•The carvacrol was dose-dependent in the oocytes of semi-engorged females of Rhipicephalus sanguineus sensu lato.•The results showed that the lower concentration (20 μL/mL), the main alterations ...were: folds at the cellular boundary, irregularities in the germinal vesicle and cytoplasmic vacuolations.•The highest concentration (100 μL/mL), inhibiting the oocyte development, since in this dosage only oocytes were found in the initial stage (I and II).
Currently, the most commonly used method to control ticks is the use of synthetic acaricides. However, these compounds are potentially harmful to hosts and the environment, in addition to causing the selection of resistant individuals. Therefore, several studies have been conducted to find sustainable methods to control ticks, such as Rhipicephalus sanguineus sensu lato, the most important vectors of pathogens for dogs. There has been increasing research on natural products with acaricidal action, especially with regard to plant-derived compounds as carvacrol, an aromatic monoterpene with several biological properties, including repellent and acaricidal activities, besides exerting cytotoxic effects on the exposed ticks. The objective of the present study was to evaluate the action of different carvacrol concentrations on the ovaries morphophysiology in semi-engorged R. sanguineus s.l. females to determine its effect on oocyte development. The results showed the occurrence of significant morphological alterations in the shape of oocytes (from round-shaped to irregular) and in the germinal vesicles, in addition to extensive cytoplasmic vacuolation.These effects were observed after the application of carvacrol at a concentration of 20 μL/mL. The most significant alterations were observed at the highest concentration (100 μL/mL), at which the oocytes could not develop further than stage II (total absence of oocytes III, IV and V). These data showed that even though carvacrol was unable to kill all ticks at these concentrations, surviving females could have had an altered reproduction, which would hinder the generation of new individuals, resulting in a long-term control. Data regarding the inhibition of oocyte development are unprecedented and indicate the use of carvacrol as a natural product with the potential to control R. sanguineus s.l. ticks.
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