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 (...

Behavioural and electrophysiological responses to overlooked female pheromone components in the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae)

The olive fruit fly, Bactrocera oleae, has a peculiar sexual chemoecology, guided by both male- and female-borne olfactory cues, mostly produced in rectal glands. Despite the research on B. oleae female pheromones has a long history, only few components (mainly 1,7-dioxaspiro[5.5]undecane) have been deeply investigated. Detailed evidences about the chemical identity and bioactivity of several others C10–C18 molecules produced in female rectal glands are lacking. We conducted GC and GC/EI–MS, identifying nine sex-specific chemicals and an additional compound [ethyl(Z)-9-octadecenoate], less abundant in females over males. Age-related production of all compounds raised over time. In 21-day-old females, it reached amounts from a minimum of 8.08 ng/fly (n-butyl dodecanoate) to a maximum of 87.19 ng/fly (ethyl hexadecanoate). In EAG experiments, all chemicals were perceived by both sexes. Methyl hexadecanoate and ethyl decanoate attracted males and females, respectively. This is the first report on a female-borne compound attracting conspecific females in Tephritidae. Our study sheds light on the bioactivity of female-borne pheromones involved in the B. oleae chemoecology. Further research is ongoing to test methyl hexadecanoate and ethyl decanoate as lures to enhance sex pheromone blends used in IPM programmes against B. oleae, thus improving control tools against this key pest

Electrophysiological and behavioural response of Philaenus spumarius to essential oils and aromatic plants

The meadow spittlebug, Philaenus spumarius, is a highly polyphagous widespread species, playing a major role in the transmission of the bacterium Xylella fastidiosa subspecies pauca, the agent of the “Olive Quick Decline Syndrome”. Essential oils (EOs) are an important source of bio-active volatile compounds that could interfere with basic metabolic, biochemical, physiological, and behavioural functions of insects. Here, we report the electrophysiological and behavioural responses of adult P. spumarius towards some EOs and related plants. Electroantennographic tests demonstrated that the peripheral olfactory system of P. spumarius females and males perceives volatile organic compounds present in the EOs of Pelargonium graveolens, Cymbopogon nardus and Lavandula officinalis in a dose-dependent manner. In behavioral bioassays, evaluating the adult responses towards EOs and related plants, both at close (Y-tube) and long range (wind tunnel), males and females responded differently to the same odorant. Using EOs, a clear attraction was noted only for males towards lavender EO. Conversely, plants elicited responses that varied upon the plant species, testing device and adult sex. Both lavender and geranium repelled females at any distance range. On the contrary, males were attracted by geranium and repelled by citronella. Finally, at close distance, lavender and citronella were repellent for females and males, respectively. Our results contribute to the development of innovative tools and approaches, alternative to the use of synthetic pesticides, for the sustainable control of P. spumarius aiming to contrasting the expansion of X. fastidiosa