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Relevance. Trophic relationships along with competition and mutualism are the most basic and significant interactions in ecosystems. To develop, survive, and multiply, insects need to consume a certain amount of nutrients at a certain ratio. Food products are complex mixes of nutrients and non-nutritive substances (sometimes toxic ones): macronutrients (proteins, carbohydrates, and lipids), micronutrients (vitamins and minerals), and water. Some nutrients are essential; insects lack the ability to synthesize them in their bodies and must obtain them from their diet or through symbiosis with beneficial organisms. Identification mechanisms being well developed in the system “phytophagous insect – plant” allow insects to successfully spread, multiply, and feed on certain plant species. The complex of hydrolytic enzymes in the insect intestine is one of the main targets for plant defense responses because these enzymes determine the availability of structural compounds for phytophagous insects. For this reason, enzymes in the insect intestine play a key role in the adaptation of insects to the pest resistance of fodder plants. For instance, when proteinase inhibitors are synthesized in a fodder plant as the result of induced insect resistance the complex of enzymes in an insect intestine might change negating the effect of these inhibitors. The development of co-adaptations due to interactions among species in food chains depends on a complicated constellation of conflicting relationships between consumers and food objects. The mechanisms of this influence may be rooted in the allelochemical interactions in the system “phytophagous insect – plant recipient”. Allelopathic interactions are among the most complex interactions because they are constituted by direct and indirect effects. Plants when damaged by phytophagous insects activate defense responses, which incorporate several mechanisms, including an increase in the concentration of secondary metabolites, many of which are phenolic compounds.The aim of the work is to describe the mechanisms of relationships in the system “phytophage-plant”. Conclusion. Management of processes of intra-water divergence of insect-phytophages in agrobiocoenoses in order to prevent the emergence of races and populations of pests adapted to live on initially resistant to them plant forms is possible in compliance with the transition to a targeted selection of agricultural crops for resistance to a complex of pests.

The exploration of natural plant growth enhancers is crucial for sustainable agriculture and environmental conservation, as well as for discovering new sources of bioactive compounds with pharmacological potential. In this study, we aimed to investigate growth-promoting effect of Dermatocarpon miniatum and Parmelia saxatilis lichens on Ceratophyllum demersum propagated in vitro. Furthermore, we revealed antioxidant capacity variation (DPPH scavenging and metal chelating activities, as well as total phenol and flavonoid contents) in lichen-treated plant (allelopathic plant). C. demersum was subjected to methanol and water extracts from lichens, specifically D. miniatum and P. saxatilis. For P. saxatilis, the methanol extract at 90 mg/L achieved the highest shoot number (189.13 shoots) and the longest shoot length (4.86 cm) using a 50 mg/L water extract. Notably, IC50 values revealed that water extracts from allelopathic plants were the most effective, with the lowest IC50 value of 48.20 mg/L for metal chelation and 53.60 mg/L for DPPH scavenging. In addition, the total phenol and flavonoid contents were significantly higher in allelopathic plants than in control plants. The methanol extract from allelopathic samples contained the highest phenol content (73.93 µg gallic acid equivalent/mg extract) and flavonoid content (66.26 µg µg quercetin equivalent/mg extract). In conclusion, this study will provide valuable input for future investigation in domain of plant development control and augmentation of biologically active substance propagation in plants, with a particular focus on utilizing P. saxatilis lichen.Key message: Since Ceratophyllum demersum L. is important as a medicinal and ornamental plant, the allelopathic mechanism is important to increase its production efficiency. [ABSTRACT FROM AUTHOR]

Agriculture runoffs and discharge of wastewaters are the major causes of eutrophication. Although eutrophication could promote the thriving of any phytoplankter, harmful algal blooms (HABs) are dominated frequently by cyanobacteria. Currently, HABs dominated by the toxigenic cyanobacterium Microcystis aeruginosa in lakes and reservoirs are the main environmental concerns worldwide. This study aimed to determine how M. aeruginosa (Ma) modifies the population growth of Pseudokirchneriella subcapitata (Ps) and Ankistrodesmus falcatus (Af). Growth kinetics were determined for each species and in the combinations: Ps–Ma, Af–Ma, Af–Ps, and Ps–Af–Ma. At the end of experiments, photosynthetic pigments, phycobiliproteins, and microcystins were quantified. A logistic equation significantly described the growth trend for all of the tested species, enabling the identification of negative effects on early stages in the population growth of co‐cultures with the cyanobacterium; in addition, the interaction effects on the growth rate and in the maximum attainable population density were determined. The biomasses of A. falcatus and P. subcapitata were significantly higher when cultured individually than in all of the combinations with the cyanobacterium. The concentrations of chlorophyll a and b, as well as carotenoids, were lower in combined cultures, but phycobiliprotein content in the cultures with M. aeruginosa was not significantly affected. Microcystis aeruginosa negatively affected the growth of the microalgae, but A. falcatus was significantly more inhibited than P. subcapitata; however, microcystin concentrations were significantly reduced in the co‐cultures with microalgae. These results could help to explain the displacements of microalgae when cyanobacteria are present, giving rise to cyanobacterial blooms in eutrophic freshwaters. [ABSTRACT FROM AUTHOR]

The pine engraver beetle, Ips acuminatus Gyll, is a bark beetle that causes important damages in Scots pine (Pinus sylvestris) forests and plantations. As almost all higher organisms, Ips acuminatus harbours a microbiome, although the role of most members of its microbiome is not well understood. As part of a work in which we analysed the bacterial diversity associated to Ips acuminatus, we isolated the strain Arthrobacter sp. IA7. In order to study its potential role within the bark beetle holobiont, we sequenced and explored its genome and performed a pan-genome analysis of the genus Arthrobacter, showing specific genes of strain IA7 that might be related with its particular role in its niche. Based on these investigations, we suggest several potential roles of the bacterium within the beetle. Analysis of genes related to secondary metabolism indicated potential antifungal capability, confirmed by the inhibition of several entomopathogenic fungal strains (Metarhizium anisopliae CCF0966, Lecanicillium muscarium CCF6041, L. muscarium CCF3297, Isaria fumosorosea CCF4401, I. farinosa CCF4808, Beauveria bassiana CCF4422 and B. brongniartii CCF1547). Phylogenetic analyses of the 16S rRNA gene, six concatenated housekeeping genes (tuf-secY-rpoB-recA-fusA-atpD) and genome sequences indicated that strain IA7 is closely related to A. globiformis NBRC 12137T but forms a new species within the genus Arthrobacter; this was confirmed by digital DNA-DNA hybridization (37.10%) and average nucleotide identity (ANIb) (88.9%). Based on phenotypic and genotypic features, we propose strain IA7T as the novel species Arthrobacter ipsi sp. nov. (type strain IA7T = CECT 30100T = LMG 31782T) and suggest its protective role for its host. [ABSTRACT FROM AUTHOR]

Marine sessile organisms often inhabit rocky substrata, which are crowded by other sessile organisms. They acquire living space via growth interactions and/or by allelopathy. They are known to secrete toxic compounds having multiple roles. These compounds have been explored for their possible applications in cancer chemotherapy, because of their ability to kill rapidly dividing cells of competitor organisms. As compared to the therapeutic applications of these compounds, their possible ecological role in competition for space has received little attention. To select the potential candidate organisms for the isolation of lead cytotoxic molecules, it is important to understand their chemical ecology with special emphasis on their allelopathic interactions with their competitors. Knowledge of the ecological role of allelopathic compounds will contribute significantly to an understanding of their natural variability and help us to plan effective and sustainable wild harvests to obtain novel cytotoxic chemicals. This review highlights the significance of studying allelopathic interactions of marine invertebrates in the discovery of cytotoxic compounds, by selecting sponge as a model organism. [ABSTRACT FROM AUTHOR]

Natural herbicides may be more sustainable than their chemical homologues, but they are still toxic substances that can affect humans and animals. Implementation of natural herbicides may require just as many safety precautions as the application of commercial herbicides, hence the need not to confuse the term "organic" with "non toxic". Allelopathy is accomplished through chemical inhibition of species towards each other, being an antagonistic phenomenon. Response and adaptation of Zea mays plants under optimal conditions are assured by the existence of a complex system of adjustment at different levels of organization. At the molecular level, the negative impact of the stressor can be to some extent a consequence of oxidative damage, as biologically important molecules following imbalances between the productions of reactive oxygen species and antioxidative protection. The subject of this survey consists in assessing the action of extractive solutions produced from Aesculus hippocastanum on the enzymatic activity, the amount of chlorophyll, and the root elongation for the mitotic film the plant cells, performed by phytobiological Mays test using Zea mays ssp.. In this context, the purpose of the present study consists in assessing the role of antioxidant enzymes in the formation and development tolerance of Zea mays plants throughout their development. [ABSTRACT FROM AUTHOR]

The paralytic shellfish toxin (PST) producing dinoflagellate Alexandrium ostenfeldii forms dense, recurrent blooms during summer in shallow coastal areas of the Baltic Sea. We studied the intra-population variability of its allelochemical potency and the responses of co-occurring and potentially competing dinoflagellates to the allelochemicals. The lytic activity of 10 northern Baltic A. ostenfeldii strains was evaluated by their EC 50 values (i.e. the cell concentration yielding a 50% decline in cryptophyte density), which were found to vary between 236 and 1726 cells ml −1 . When co-occurring dinoflagellates ( Kryptoperidinium foliaceum , Levanderina fissa and Heterocapsa triquetra ) were exposed to filtrate of A. ostenfeldii , short-term (<1 h) responses of the target species after an initial immobilization were species-specific. Almost all of the K. foliaceum cells formed cysts, L. fissa cells lost their cell shape and lysed, whereas H. triquetra cells shed their thecae. After 24 h, K. foliaceum had returned into vegetative cells and the number of immotile L. fissa and H. triquetra cells had significantly decreased. The results indicate that A. ostenfeldii can disturb the growth of competing dinoflagellates by excreting allelochemicals at bloom concentrations and that co-occurring species may develop efficient means to escape and recover from the allelochemicals, allowing them to coexist with A. ostenfeldii . [ABSTRACT FROM AUTHOR]

4-Nonylphenol (4-NP) is an anthropogenic contaminant found in different environmental matrices that has an effect over the biotic and abiotic factors within the environment. Bioremediation by microorganisms can be used as a potential treatment to remove this pollutant. In this work, a consortium of two microorganisms, Arthrospira maxima and Chlorella vulgaris, was employed to remove 4-NP from water. The parameters analyzed included cell growth, removal of 4-NP, and 4-NP remnant in the biomass. In addition, the metabolites produced in the process by this consortium were identified. It was found that C. vulgaris is more resistant to 4-NP than A. maxima (cell growth inhibition by 4-NP of 99%). The consortium used in this study had an IC 50 greater than any strain of microalgae or cyanobacteria reported for 4-NP removal (9.29 mg/L) and reduced up to 96% of 4-NP in water in the first 48 h of culture. It was also observed that there is a bio-transformation of 4-NP, comparable with the process carried out by another bacterium, in which three similar metabolites were found (4-(1-methyl-octyl)-4-hydroxy-cyclohex-2-enone, 4-nonyl-4-hydroxy-ciclohexa-2,5-dienone and 4-nonyl-4-hydroxy- ciclohex-2-enone) and one that is similar to plant metabolism (4-nonyl-(1-methyl,6,8-metoxy)-hydroxybenzene). These results indicate that microalgae and cyanobacteria consortium can be used to remove 4-NP from water. • The consortium of A. maxima and C. vulgaris was able to remove 4-NP in water. • A. maxima and C. vulgaris consortium had an IC 50 of 9.29 mg/L for 4-NP. • A. maxima and C. vulgaris consortium showed an allelopathic interaction. • The maximum removal efficiency of 98% was noted for 4-NP under the optimized conditions. [ABSTRACT FROM AUTHOR]