Fusarium head blight (FHB) of wheat, is caused by fungal populations belonging to the Fusarium graminearum species complex. Although triazole fungicides are widely used in FHB management, information about the sensitivity of F. graminearum populations to such fungicides is scarce, particularly in Brazil. This work aimed at determining the sensitivity of pathogenic populations of F. graminearum to metconazole and tebuconazole. Fungal isolates were obtained from diseased wheat heads collected in commercial fields at the northern region of Rio Grande do Sul state, Brazil, along the 2009 and 2010 growing seasons. Fifty isolates obtained from eleven locations were grown in media amended with increasing fungicide dosages and the effective concentration reducing mycelial growth to 50% (EC 50 ) was determined. The median of the EC 50 values was 0.001 mg/L (<0.001-0.152 mg/L) and 0.037 mg/L (<0.001-0.324), for tebuconazole and metconazole, respectively. Cross-resistance was detected based on significance of correlation analysis (r s = 0.46; P < 0.0001) between the log-transformed EC 50 of the two triazoles. The mean EC 50 for a group of ten isolates classified as "more sensitive" differed statistically from the ten isolates representing the "less sensitive" group. Nevertheless, these groups did not differ in terms of mycelial growth on PDA in the absence of fungicides. It was concluded that pathogenic populations of F. graminearum are sensitive to the triazoles at various levels due to the intrinsic characteristics of the isolates or to selection pressure by the increasing fungicide use.

Pear psyllids are the main vectors of the pathogen ‘Candidatus Phytoplasma pyri’ causing pear decline. Based on earlier reports, we tested the behavioral activity of the major synthetic compounds of clove essential oil (eugenol, eugenyl acetate, and β-caryophyllene) against Cacopsylla pyri and C. pyricola. Of six mixtures tested in olfactometer assays, a formulation consisting of three specific compounds (M6 mixture) demonstrated a repellent effect on both psyllid species. In addition, this formulation masked the odor of the host Pyrus communis cv. Williams Christ, disturbing the host finding ability of C. pyri. Electrospun fibers were produced with biocompatible polymers poly(ε-caprolactone), cellulose acetate, and solvents formic acid and acetic acid, loaded with the repellent mixture to test their efficacy as dispensers of repellents in laboratory and field. The fibers produced were repellent to C. pyri and effectively masked the odors of pear plants in olfactometer tests. In a pear orchard, we compared the captures of pear psyllids in green-colored attractive traps treated with nanofibers loaded with M6 mixture or unloaded nanofibers (blank). The result showed no differences in the captures of C. pyri between treatments. The release rates of volatiles from the fibers were evaluated weekly over 56 days. The fibers were able to entrap the major compound of the M6 mixture, eugenol, but the release rates were significantly reduced after 21 days. Our results suggest that biodegradable dispensers could be produced with electrospinning, but further improvements are necessary to use repellents as a management tool for pear psyllids in the field.

Incorporation of cypermethrin in nanofibres did not interfere with G. molesta attractiveness. Both aspects of the strategy, the attractant and killing effects, were recorded using innovative nanofibres, and long-term effects suggest a controlled release of pheromone and insecticide. © 2017 Society of Chemical Industry.

The Mediterranean fruit fly (medfly), Ceratitis capitata (Wied.) is considered a serious pest of citrus fruits in the southeast of Brazil because of the direct economic impact they have on fruit production and quarantine restrictions for fruit exports. Monitoring and detection of the medfly, using food bait and synthetic attractants, is a key step towards signalling the need for management and control. The aim of this study has been to verify the attractiveness of innovative nanofiber formulations with Trimedlure (TML) for the male of C. capitata in laboratory and field cage tests. Material and Methods:The nanofibers were produced by solution or emulsion electrospinning, containing TML and polymers, such as polycaprolactone, PEG-polycaprolactone, ethyl cellulose and polyvinyl acetate-PVP.Results: At the laboratory the electrophysiological responses were accessed by the eletroanntenogram technique and in the field by the cage test. The bioactivity of C. capitata antennae was highest when stimulated with all TML nanofiber treatments rather than their controls. There were no differences among the TML nanofiber treatments. In the field cages the same number of medflies were found on the adhesive traps baited with one of each of the TML nanofibers.