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Amitraz and tau-fluvalinate are veterinary treatments administered for the control of Varroa destructor in honey bee colonies. These treatments can generate harmful residues for bees. This field study addresses the issue under two scenarios: 1) administration according to the posology and 2) placing contaminated wax containing the treatments. Tau-fluvalinate (Apistan®) residues were detected in larval stages from 25.34 to 84.72 ng g−1 in scenario 1 and from 29.63 to 173.97 ng g−1 in scenario 2. In addition, it was detected in bee bread in scenario 2 from 55.72 to 573.79 ng g−1. In scenario 1, DMPF + DMF (amitraz metabolites) were found from 37.09 to 171.58 ng g−1 (Amicel®) and from 36.74 to 42.64 ng g−1 (Apivar®) in bee bread. In honey, DMPF + DMF ranged from 19.96 to 145.30 ng g−1 (Amicel®) and from 32.20 to 78.43 ng g−1 from (Apivar®). With these treatments, a significant reduction in the population of Varroa mites (mean ± s.d.) was observed between 95.15 ± 2.56% and 98.29 ± 1.97%. There were significant positive correlations between Amicel®, the population of adult bees and the population of brood during evaluation 2 showing a higher effectiveness. According to both RQ (Risk Quotient) and SRA (Standard Risk Approach) values for adult bees and larvae, there is no risk when considering exposure by contact or by ingestion of bee bread or honey. In scenario 2, there is no risk for most of the larval stages, except in two bee hives treated with tau-fluvalinate, where the SRA values were 1.73 and 1.29%, indicating a moderate risk due to acute oral exposure.

Democracy matters for international merger activity. Using a sample of 101,834 cross-border deals announced between 1985 and 2018, we show that merger flows predominantly involve acquirers from more democratic countries than their targets. This result is primarily driven by a “pull” factor: firms in countries with weaker democratic institutions attract more cross-border deals. We find evidence of bonding as the key mechanism behind this effect. The democracy effect is stronger when target countries have weaker corporate governance standards. Furthermore, target abnormal returns around deal announcements increase with the difference in democracy between acquirer and target countries. Importantly, differences in investor protection or economic development do not directly explain the democracy effect. Combined, our findings imply that democracy is a fundamental, yet previously overlooked, determinant of cross-border mergers.

Chloride (Cl) is traditionally categorized as an antagonist of nitrate (NO3¿) because Cl¿ hinders plant NO3¿ transport and accumulation. However, we have recently defined Cl¿ as a beneficial macronutrient for higher plants, due to specific functions that lead to more efficient use of water, nitrogen (N) and CO2 under optimal N and water supply. When accumulated in leaves at macronutrient levels, Cl¿ promotes growth through osmotic, physiological, metabolic, anatomical and cellular changes that improve plant performance under optimal NO3¿ nutrition. Nitrate over-fertilization in agriculture can adversely affect crop yield and nature, while its deficiency limits plant growth. To study the relationship between Cl¿ nutrition and NO3¿ availability, we have characterized different physiological responses such as growth and yield, N-use efficiency, water status, photosynthesis, leaf anatomy, pigments and antioxidants in tomato plants treated with or without 5 mM Cl¿ salts and increasing NO3¿ treatments (3¿15 mM). First, we have demonstrated that 5 mM Cl¿ application can reduce the use of NO3¿ in the nutrient solution by up to half without detriment to plant growth and yield in tomato and other horticultural plants. Second, Cl¿ application reduced stress symptoms and improved plant growth under low-NO3¿ conditions. The Cl¿-dependent resistance to low-N stress resulted from: more efficient use of the available NO3¿; improved plant osmotic and water status regulation; improved stomatal conductance and photosynthetic rate; and better antioxidant response. We proposed that beneficial Cl¿ levels increase the crop ability to grow better with lower NO3¿ requirements and withstand N deficiency, promoting a more sustainable and resilient agriculture.

Coumaphos is a veterinary treatment administered for the control of Varroa destructor in honey bee colonies. The detection of its residues, however, has been frequently reported in beeswax. This study is pioneer to investigate whether the honey bee brood is exposed to coumaphos via contact or by ingestion of food resources due to a residue transfer inside the bee hive. This field study addresses two scenarios: 1) after its administration according to the posology using strips inside the bee hives and, 2) placing contaminated wax containing coumaphos at 10 mg/Kg into the bee hives (simulating the use of recycled wax). In bee bread, the average concentrations of residues (mean ± s.d.) were 246.66 ± 772.29 ng/g and 192.55 ± 320.19 ng/g in scenario 1 and 2, respectively. In honey, residue concentration was 1.98 ± 5.41 ng/g and 1.93 ± 6.59 ng/g. In scenario 2, exposure has led to residue detection in all larval stages at concentrations ranging from 51.93 to 383.42 ng/g (larvae), 42.20-58.54 ng/g (prepupae), 18.35-26.24 ng/g (pupae) to 21.92-35.92 ng/g (born bee). This study shows that there is a high risk for the bee brood (larvae) by ingestion of bee bread when the residue concentration is >251.31 ng/g. Residue levels in larvae or in prepupae >42.20 ng/g give rise to a moderate risk.

Chloride (Cl−) and nitrate (NO−3) are closely related anions involved in plant growth. Their similar physical and chemical properties make them to interact in cellular processes like electrical balance and osmoregulation. Since both anions share transport mechanisms, Cl− has been considered to antagonize NO−3 uptake and accumulation in plants. However, we have recently demonstrated that Cl− provided at beneficial macronutrient levels improves nitrogen (N) use efficiency (NUE). Biochemical mechanisms by which beneficial Cl− nutrition improves NUE in plants are poorly understood. First, we determined that Cl− nutrition at beneficial macronutrient levels did not impair the NO−3 uptake efficiency, maintaining similar NO−3 content in the root and in the xylem sap. Second, leaf NO−3 content was significantly reduced by the treatment of 6 mM Cl− in parallel with an increase in NO−3 utilization and NUE. To verify whether Cl− nutrition reduces leaf NO−3 accumulation by inducing its assimilation, we analysed the content of N forms and the activity of different enzymes and genes involved in N metabolism. Chloride supply increased transcript accumulation and activity of most enzymes involved in NO−3 assimilation into amino acids, along with a greater accumulation of organic N (mostly proteins). A reduced glycine/serine ratio and a greater ammonium accumulation pointed to a higher activity of the photorespiration pathway in leaves of Cl−-treated plants. Chloride, in turn, promoted higher transcript levels of genes encoding enzymes of the photorespiration pathway. Accordingly, microscopy observations suggested strong interactions between different cellular organelles involved in photorespiration. Therefore, in this work we demonstrate for the first time that the greater NO−3 utilization and NUE induced by beneficial Cl− nutrition is mainly due to the stimulation of NO−3 assimilation and photorespiration, possibly favouring the production of ammonia, reductants and intermediates t

The functions of iron, manganese, copper, zinc, nickel, molybdenum, boron, and chlorine in plants are discussed. Iron (Fe) plays a crucial role in redox systems in cells and various enzymes. The strategies of dicotyledonous and graminaceous plants to acquire Fe are described. Manganese (Mn) and copper (Cu) are important for redox systems and as activators of various enzymes involved in photosynthesis, detoxification of superoxide radicals and the synthesis of lignin. Zinc (Zn) plays a key role in the structural and functional integrity of cell membranes, biosynthesis of proteins, and detoxification of superoxide radicals. Nickel (Ni) is involved in nitrogen (N) metabolism as metal component of the enzyme urease. Molybdenum (Mo) is important for N metabolism as metal component of nitrogenase (N2 fixation) and nitrate reductase. Boron (B) is crucial for the stability and function of cell wall and membranes, whereas chlorine (Cl) is essential for the proper functioning of photosystem II and cell osmotic regulation. For each micronutrient, the effects of deficiency and toxicity are described.

The use of peat in traditional cultivation systems and in commercial nurseries is an environmental problem. In this work, we evaluated the partial replacement of peat with different amounts of biochar sourced from vineyard pruning as plant growing substrates. We studied its effect on the growth of lettuce plants under greenhouse and semi-hydroponic conditions. Substrate mixtures contained 30% (v/v) of vermiculite and 70% (v/v) of different biochar:peat treatments as follows: 0:70 (B0), 15:55 (B15), 30:40 (B30), 50:20 (B50), and 70:0 (B70). Higher biochar treatments increased the pH and electrical conductivity of the substrate, negatively affecting plant growth and germination (especially in B70). The partial substitution of peat by 30% biochar (B30) delayed seed germination but improved plant growth and nitrogen use efficiency (NUE), with shoots containing higher levels of organic nitrogen and nitrate. Moreover, it increased the water holding capacity (WHC) and led to an efficient use of nutrients. Our study demonstrates that biochar can successfully replace and reduce peat and N fertilizer consumption. This has the potential to promote more sustainable farming with positive impacts on both plant growth and the environment.

The identification of rootstocks of low susceptibility to Verticillium dahliae can become a valuable procedure to achieve effective control of Verticillium wilt in the olive grove. This not only involves the identification of suitable genotypes, but also the study of the interaction between the rootstock and the grafted scion. Thus, a rootstock that prevents or minimizes V. dahliae proliferation (avoidance/resistance strategy) can have very different effects on a susceptible scion compared to a rootstock that shows few or no symptoms despite being infected (tolerance strategy). Both resistance and tolerance mechanisms have been recently identified in wild olive genotypes with low susceptibility to V. dahliae. When used as rootstocks of the highly susceptible variety ‘Picual’, we found that resistant genotypes, including the cultivar ‘Frantoio’, were more effective than tolerant genotypes in controlling Verticillium wilt. Furthermore, tolerant genotypes were as ineffective as susceptible or extremely susceptible genotypes in controlling Verticillium wilt. We also identified rootstock-scion combinations with behaviours that were not expected according to the degree of susceptibility previously observed in the non-grafted rootstock. Although the rootstocks were able to control Verticillium wilt according to its degree of susceptibility to V. dahliae, the ability to control the infection was not adequately transferred to the grafted scion. Our results confirmed that: the degree of susceptibility to Verticillium wilt of an olive variety does not predict its performance as a rootstock; to use a very low susceptible genotype as rootstock of a susceptible scion increases the susceptibility of the genotype used as rootstock; in any case, avoidant/resistant rootstocks are more effective than tolerant rootstocks in reducing the susceptibility of the grafted plant to V. dahliae. Copyright © 2022 Díaz-Rueda, Peinado-Torrubia, Durán-Gutiérrez, Alcántara-Romano, Aguado, Capote and

Chloride (Cl−) and nitrate ((Formula presented.)) are closely related anions involved in plant growth. Their similar physical and chemical properties make them to interact in cellular processes like electrical balance and osmoregulation. Since both anions share transport mechanisms, Cl− has been considered to antagonize (Formula presented.) uptake and accumulation in plants. However, we have recently demonstrated that Cl− provided at beneficial macronutrient levels improves nitrogen (N) use efficiency (NUE). Biochemical mechanisms by which beneficial Cl− nutrition improves NUE in plants are poorly understood. First, we determined that Cl− nutrition at beneficial macronutrient levels did not impair the (Formula presented.) uptake efficiency, maintaining similar (Formula presented.) content in the root and in the xylem sap. Second, leaf (Formula presented.) content was significantly reduced by the treatment of 6 mM Cl− in parallel with an increase in (Formula presented.) utilization and NUE. To verify whether Cl− nutrition reduces leaf (Formula presented.) accumulation by inducing its assimilation, we analysed the content of N forms and the activity of different enzymes and genes involved in N metabolism. Chloride supply increased transcript accumulation and activity of most enzymes involved in (Formula presented.) assimilation into amino acids, along with a greater accumulation of organic N (mostly proteins). A reduced glycine/serine ratio and a greater ammonium accumulation pointed to a higher activity of the photorespiration pathway in leaves of Cl−-treated plants. Chloride, in turn, promoted higher transcript levels of genes encoding enzymes of the photorespiration pathway. Accordingly, microscopy observations suggested strong interactions between different cellular organelles involved in photorespiration. Therefore, in this work we demonstrate for the first time that the greater (Formula presented.) utilization and NUE induced by beneficial Cl− nutrition is mainl