Eficiencia agronómica de la fertilización nitrogenada del cultivo de trigo, con dos fuentes y en dos zonas del sur bonarense

La eficiencia de uso de nitrógeno (EUN) aplicado con el fertilizante es un dato importante para maximizar la inversión de esta práctica. Existen opiniones encontradas en cuanto a que las diferentes fuentes presentarían diferencias respecto de este parámetro. El objetivo del presente trabajo fue determinar la EUN de dos fertilizantes nitrogenados (urea y nitrato de amonio calcáreo-CAN) aplicados en el cultivo de trigo en dos zonas del sudeste bonaerense, Necochea y Pigüé. Para ello, se realizó un ensayo de fertilización nitrogenada aplicado en cobertura con dosis crecientes de ambos fertilizantes (100, 150 y 250 kg ha-1 en Necochea y 50, 100, 150 y 200 kg ha-1.en Pigüé). Las dosis de fertilizantes se fijaron tomando como referencia las dosis más utilizadas en cada zona. Los resultados evidenciaron diferencias en EUN de los dos fertilizantes evaluados, siendo de 36.2, 37 y 20.7 kg de trigo kg N aplicado-1 para las dosis de 100, 150 y 250 kg ha-1 de CAN y 16.3, 15.1 y 12.2 de trigo kg N aplicado-1 para las dosis de 100, 150 y 250 kg ha-1 de urea respectivamente. Para la localidad de Pigüe se obtuvieron 22.7, 19.2, 19.2, 21.8 kg de trigo kg N apliacado-1 para las dosis de 50, 100, 150 y 200 kg ha-1 de CAN y 6.7, 14.4, 10.4 y 11.7 de trigo kg N aplicado-1 para las dosis de 50, 100, 150 y 200 kg ha-1 de urea respectivamente. En base a los resultados obtenidos se aceptaría la hipótesis de que en ambos ambientes existirán diferencias a favor del CAN en la EUN en fertilizaciones de trigo en cobertura

Electrophysiological and Behavioral Responses of Theocolax elegans (Westwood) (Hymenoptera: Pteromalidae) to Cereal Grain Volatiles

Volatiles emitted by the host's food would be the first signals used by parasitoids in the host location process and are thought to play an important role in host habitat location. In this study, the olfactory responses of Theocolax elegans (Westwood), a Pteromalid wasp that parasitizes immature stages of stored-product insect pests developing inside cereal or leguminous grains, to volatiles emitted by healthy wheat grains, their hexane extracts, and different doses of three individual compounds previously identified in cereal grain odors were investigated in Y-tube olfactometer and Petri dish arena behavioral bioassays and electroantennogram recordings. In Y-tube olfactometer bioassays, odors from healthy wheat grains and their hexane extracts were attractive to both sexes of T. elegans. Moreover, hexane extracts elicited arresting effects in Petri dish arena. The three synthetic compounds valeraldehyde, maltol, and vanillin elicited dose-dependent responses in both male and female adult wasps confirming the capability of the peripheral olfactory systems to perceive cereal volatiles. In behavioral bioassays, different doses of vanillin were significantly attractive to both sexes

Electroantennographic responses of Aromia bungii (Faldermann, 1835) (Coleoptera, Cerambycidae) to a range of volatile compounds

The red-necked longhorn beetle, Aromia bungii, is one of the most damaging pests of stone fruit trees. Native to the south-eastern Palearctic and Oriental regions, it invaded and is established to some extent in the Campania Region (Southern Italy). In several cerambycid species, volatile organic compounds (VOCs) have been shown to play a role in mate and host plant location. Increasing EAG amplitudes from the basal to the distal antennal segments were recorded in response to six selected plant volatiles. From the distal flagellomeres, the largest EAG responses (>0.8 mV) were elicited by 2-hexanol, octanal, sulcatone, guaiacol, sulcatol, 2,4-dimethyl-3-hexanol, 2,4-dimethyl-2-hexanone, heptanal, nonanal, (Z)-3-hexenol, and 1-heptanol in both sexes, and by linalool, (E)-2-heptenal, 1-octen-3-ol, (E)-2-octenal, 3-octanol, (E)-2-octen-1-ol, alfa-phellandrene, and alfa-terpinene in males. The olfactory system of both sexes proved to be sensitive to changes in stimulus concentration and compound structure. This study demonstrates the capability of A. bungii males and females to detect and discriminate among a wide range of VOCs and provides a basis for further olfactometer and field trapping experiments aimed at identifying behaviorally-active compounds useful for the implementation of semiochemical-based control strategies for this pest

Electrophysiological and behavioral activity of (E)-2-hexenal in the granary weevil and its application in food packaging.

The purpose of this work was to develop a biodegradable carrier material to control insect pests in cereal products. To this aim, (E)-2-hexenal was used, being a natural compound with antimicrobial activity that is also commonly adopted as a flavoring agent. Three coating layers of polycaprolactone (PCL) were spread onto the internal side of a paperboard carton, the first being the active coating containing (E)-2-hexenal. The antennal sensitivity of Sitophilus granarius to a broad range of doses of (E)-2-hexenal was first demonstrated. Next, the ability of different concentrations of this compound to disrupt the orientation of adult S. granarius beetles to odors of intact wheat kernels was established in a two-choice pitfall bioassay. In addition, invasion tests were carried out over an 8-week period to highlight the effects of the biobased repellent packaging and their potential persistence. The results demonstrated that during the entire monitoring period, the percentage of S. granarius adults found in cartons coated with (E)-2-hexenal-loaded multilayer PCL was about 10 % of the total number of insects used in the bioassay, very low compared with the respective control samples, thus assessing both the effectiveness and persistence of the repellent system developed. Although the infestation level of treated packages was reduced relative to the infestation levels in the controls, any infestation of food packages is unacceptable to consumers, so further tests are required to determine whether infestation can be completely prevented using (E)-2-hexenal

Intruding into a conversation: how behavioral manipulation could support management of Xylella fastidiosa and its insect vectors

Behavioral manipulation (BM) is a multimodal control approach based on the interference with the stimuli mediating insect perception and interaction with the surroundings. BM could represent a win–win strategy for the management of vector-borne plant pathogens as the bacterium Xylella fastidiosa, since it could reduce the number of vectors alighting on host plants and, consequently, the chances for transmission to occur. In this review, we summarized current knowledge and highlighted gaps in information on (i) how insect vectors of X. fastidiosa in general, and more specifcally the meadow spittlebug Philaenus spumarius, locate and accept the host plant; and (ii) how behavioral manipulation techniques could be applied to disrupt the vector–host plant interaction. Finally, we discussed how diverse BM strategies could be combined with other integrated pest management tools to protect olive groves from inoculation with the fastidious bacterium

Climate and landscape composition explain agronomic practices, pesticide use and grape yield in vineyards across Italy

Context Worldwide, organic farming is being promoted as one of the main alternatives to intensive conventional farming. However, the benefits of organic agriculture are still controversial and need to be tested across wide environmental gradients. Objective Here, we carried out an observational study to test how agronomic practices, pest management, environmental impact and yield of conventional and organic vineyards changed along wide climatic and landscape gradients across Italy. Methods We used a block design with 38 pairs of conventional and organic vineyards across Italy. Results and conclusions Most agronomic practices did not differ between conventional and organic vineyards. By contrast, landscape composition and climate were strong predictors of management in both systems. First, increasing semi-natural areas around the vineyards reduced pesticide pressure and related environmental impacts, but was also associated with lower yield. Second, irrespective of the farming system, a warm and dry climate was associated with reduced fungicide pressure. Conventional farming had a yield gain of 40% in cold and wet climate compared to organic but the yield gap disappeared in the warmest regions. Significance In both farming systems, we observed a large variability in management practices that was mainly explained by climate and landscape composition. This large variability should be considered when evaluating the benefits and drawbacks of different farming systems under contrasting environmental contexts

Fertilización fosforada y nitrogenada en el cultivo de maíz dulce (Zea mays L. var. saccharata Bailey)

To evaluate the effect of combining different levels of P and N fertilisation on yield and uniformity of a sweet corncrop hybrid Freshy, a factorial trial combining three levels of N (0, 100 and 200 kg of N ha-1) and three levels of P (0,40 and 80 kg of P2O5 ha-1) was carried out. Total leaf number, height up to ear insertion, leaf width and length, leaf area,plant height, stem diameter, biomass production, shoot dry matter content, harvest index and yield with and withouthusk, husk proportion and ear diameter were measured. Significant differences in leaf width and length, leaf area, plantheight, ear diameter, biomass production and yield with and without husk were observed with N fertilisation. On theother hand, significant differences in leaf length, unit leaf area, ear diameter and biomass production were observedwith P fertilisation. A N x P interaction was only observed for shoot dry matter contentEl objetivo de este trabajo fue evaluar el efecto de la fertilización fosforada y nitrogenada sobre la uniformidad y rendimiento del cultivo de maíz dulce híbrido Freshy. Los tratamientos de fertilización fueron: 0, 100 y 200 kg de N ha sup(-1) combinados con 0, 40 y 80 kg de P2O5 ha sup(-1). Se utilizó un diseño en bloques completamente aleatorizados con tres repeticiones. Las mediciones y determinaciones fueron número total de hojas, altura hasta inserción de la espiga, ancho y longitud de hoja, área foliar, altura de planta, diámetro de tallo, producción de biomasa, porcentual de materia seca en vástago, índice de cosecha y rendimiento con y sin chala, proporción de chala y diámetro de espiga. Con la aplicación de nitrógeno se encontraron diferencias significativas para ancho y largo de hoja, área foliar, altura de planta (...

Electroantennographic Responses of Aromia bungii (Faldermann, 1835) (Coleoptera, Cerambycidae) to a Range of Volatile Compounds

Background: The red-necked longhorn beetle, Aromia bungii, is one of the most damaging pests of stone fruit trees. Native to the south-eastern Palearctic and Oriental regions, it invaded and is established to some extent in the Campania Region (Southern Italy). In several cerambycid species, volatile organic compounds (VOCs) have been shown to play a role in mate and host plant location. Methods: The electroantennographic (EAG) technique was employed to explore the antennal chemoreceptivity of male and female A. bungii antennae to 90 VOCs. Results: Increasing EAG amplitudes from the basal to the distal antennal segments were recorded in response to six selected plant volatiles. From the distal flagellomeres, the largest EAG responses (>0.8 mV) were elicited by 2-hexanol, octanal, sulcatone, guaiacol, sulcatol, 2,4-dimethyl-3-hexanol, 2,4-dimethyl-2-hexanone, heptanal, nonanal, (Z)-3-hexenol, and 1-heptanol in both sexes, and by linalool, (E)-2-heptenal, 1-octen-3-ol, (E)-2-octenal, 3-octanol, (E)-2-octen-1-ol, α-phellandrene, and α-terpinene in males. The olfactory system of both sexes proved to be sensitive to changes in stimulus concentration and compound structure. Conclusions: this study demonstrates the capability of A. bungii males and females to detect and discriminate among a wide range of VOCs and provides a basis for further olfactometer and field trapping experiments aimed at identifying behaviorally-active compounds useful for the implementation of semiochemical-based control strategies for this pest