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Trioza erytreae (Del Guercio) is one of the psyllid insect vectors of the causal agents of huanglongbing. This paper proposes an assessment of the effectiveness of several pesticides with and without a pine oil-based organic adjuvant, in order to contain the spread and population of this pest and reduce the side effects on the Tamarixia dryi parasitoid. Five insecticides and their combinations with pine oil were sprayed against T. erytreae on citrus trees under semi-field and field conditions. The effect of the same treatments was assessed on T. dryi under laboratory conditions. All insecticides, except for acetamiprid, increased their effectiveness when combined with pine oil under both conditions. Cyantraniliprole, dimethoate, and their respective combinations with the organic adjuvant showed the highest efficacies against T. erytreae. Under laboratory conditions, dimethoate reported the most negative effect on T. dryi activity whereas cyantraniliprole and its combination with pine oil yielded a low toxicity effect on this parasitoid. Our results recommend the development of an integrated control approach for citrus growers based on an insecticide rotation program, preventing the emergence of pest resistance to one substance. In this sense, other insecticides, such as lambda-cyhalothrin with pine oil adjuvant or acetamiprid, could be considered.

The second generation of Eurocode 2 incorporates formulations based on physical models which are general enough for the assessment of existing structures but can be simplified for the design of new structures, in order to improve the ease-of-use. One of the areas where these improvements are addressed is the shear verification of members without shear reinforcement, such as solid slabs, walls, cut-and-cover tunnels, precast ribs or hollow core slabs, which in some cases are prestressed or subjected to external axial loading.In current Eurocode 2, the shear verification of these structures is based on an empirical formulation proposed by Zsutty in 1968. The final draft of the new version of Eurocode 2 has adopted the Critical Shear Crack Theory (CSCT) as the theoretical basis for the formulation of the shear resistance, which allows a better understanding of structural behaviour in many different conditions, not only for the design of new structures, but also for the assessment of existing structures. This formulation accounts for some aspects that are not well considered in current Eurocode 2, which have been underlined as shortcomings in recent years.The formulation for design of new structures in the final draft of the new version of Eurocode 2 (General Model) is easy to use for the verification of the shear resistance, but requires an iterative process to calculate the shear capacity of sections in the presence of axial forces. For this reason, the final draft of the new version of Eurocode 2 also provides an alternative non-iterative formulation (Linear Approach) to calculate the shear capacity in presence of compressive axial forces, based on the linearisation of the CSCT shear failure criterion and formulated with the same additive structure as in the current Eurocode 2, useful for the most common cases.This paper presents the General Model formulation provided in the next Eurocode 2 for the shear verification of axially loaded members without shear reinforcement, as well as the alternative formulation (linear approach). In addition, the agreement of both formulations with experimental results from an available shear test database on prestressed concrete beams is shown and the consistency of the safety treatment between the two formulations is also discussed.

We consider a fully discrete loosely coupled scheme for incompressible fluid-structure interaction based on the time semi-discrete splitting method introduced in [Burman, Durst & Guzmán, arXiv:1911.06760] . The splittling method uses a Robin-Robin type coupling that allows for a segregated solution of the solid and the fluid systems, without inner iterations. For the discretisation in space we consider piecewise affine continuous finite elements for all the fields and ensure the infsup condition by using a Brezzi-Pitkäranta type pressure stabilization. The interfacial fluid-stresses are evaluated in a variationally consistent fashion, that is shown to admit an equivalent Lagrange multiplier formulation. We prove that the method is unconditionally stable and robust with respect to the amount of added-mass in the system. Furthermore, we provide an error estimate that shows the error in the natural energy norm for the system is O √ T ( √ ∆t + h) where T is the final time, ∆t the time-step length and h the space discretization parameter.

RESUMENEl trigo pan es el cultivo invernal más importante en la región semiárida pampeana, aún con el escenario de alta volatilidad de precios. Existen alternativas como la cebada forrajera y cervecera, avena, centeno, trigo candeal, alpiste, triticale, colza, cártamo y lino. El objetivo fue evaluar la factibilidad de producción de éstos. Los ensayos se realizaron en el campo de la Facultad de Agronomía de la UNLPam (36º32'54" S; 64º18'16" W), sobre un suelo Paleustol petrocálcico. Se utilizó un diseño de bloques completos al azar con 3 réplicas. Se sembraron tres épocas (2/06, 21/06 y 14/08). Las lluvias fueron suficientes para todos los cultivos, excepto para el cártamo en diciembre y enero. Los mayores rindes se lograron con el trigo pan, la cebada cervecera y forrajera de la tercera época y el triticale en la segunda. La avena, la cebada forrajera y cervecera, el centeno, el trigo candeal, el trigo pan y el cártamo tuvieron mayor rendimiento en la tercera época. El alpiste, el triticale y el lino rindieron más en la segunda época. El alpiste, el cártamo y el lino tuvieron menores rindes; su evaluación por parte del agricultor dependería de la visión de cadena de valor, nicho de mercado y rentabilidad empresarial. PALABRAS CLAVE: adaptación, cultivos alternativos, trigo pan ABSTRACTBread wheat is the most important winter crop in the Pampean Semiarid Region, even under a scenario of high volatility in commodity prices. Other crops such as feed and malting barleys, oats, rye, durum wheat, canarygrass, triticale, rapeseed, safflower and flax can be grown alternatively in that season. The objective of this study was to evaluate the production performance of those alternative winter crops. Tests were conducted in the experimental field of the Agronomy Faculty of the Universidad Nacional de La Pampa (36º32'54" S; 64º18'16" W) on a Petrocalcic Paleoustoll soil. The experiment was run using a randomized complete block design with three replicates, and three dates of sowing were assayed: june 2, june 21 and august 14. Rain falling during the trial period was enough to meet the needs for all the crops, excepting for safflower in December and January. Bread wheat and the two types of barleys sown in the latest date, and triticale sown in the second date, showed the highest grain yield. Oats, feed and malting barleys, rye, durum and bread wheats, and safflower showed their highest grain yield when sown in the third date. The highest performance for canarygrass, triticale and flax was observed for the second date of sowing. The yield of the last ones was lower than that showed by the rest of crops assayed. Therefore, their choosing by the farmer