Zeolites as pheromone dispensers

Modification of the chemical and structural properties of zeolites has led to the preparation of an optimized zeolitic dispenser for insect attractants such as n-decanol and trimedlure. The impact of zeolite variables such as the framework Si/Al ratio, nature of compensating cation, nature and strength of acid groups, and pore dimensions on the kinetics of emission has been studied, and the results are as follows. Zeolite pore dimensions and the presence or absence of acid sites have the greatest effect on the rate of release, decreasing with decreasing pore diameter and increasing acidity. Further tuning of the release characteristics is achieved by controlling the polarity and the polarizability of the framework by increasing the Si/Al ratio and nature of the compensating cations, i.e., the higher the polarizability and the lower the polarity, the slower the release of attractants.     

Mating disruption for the control of Aonidiella aurantii Maskell (Hemiptera: Diaspididae) may contribute to increased effectiveness of natural enemies

BACKGROUND: New directives on sustainable use of pesticides have encouraged research on efficient alternative pest control methods. In the case of the California red scale (CRS), Aonidiella aurantii (Maskell), this imperative, along with the many difficulties in controlling this pest, have led to the investigation of new approaches. Previously developed mating disruption (MD) dispensers, together with the augmentative releases of the parasitoid Aphytis melinus DeBach, are here considered as a combined strategy for use against A. aurantii. RESULTS: Efficacy of MD was demonstrated by a mean reduction of 80% in CRS male catches and a mean fruit damage reduction of 83% compared with the control. A delay in the development of A. aurantii instars was observed in the MD plot. This delay increased the period of exposure of the susceptible instars to natural enemies, which resulted in higher predation and parasitism levels in the MD plot. Under laboratory conditions, A. melinus mating behaviour and effects on A. aurantii were not significantly altered in a CRS-pheromone-saturated environment. CONCLUSION: Mating disruption pheromone did not affect the behaviour or level of parasitism by A. melinus or the incidence of other generalist predators. Therefore, A. aurantii pheromone appears to be compatible with augmentative releases and biological control, making its use a good strategy for CRS management. Copyright © 2011 Society of Chemical Industry     

Water status and drought stress in experimental gaps in managed and semi-natural silver fir--beech forests

The effect of gap characteristics, including gap age, vegetation cover, and stage of regeneration, on water balance and drought stress was studied over a four-year period in natural and experimental gaps of various sizes in Dinaric silver fir--beech forest in Slovenia. A medium gap, two experimental clear-cut gaps, and a closed stand were selected in a traditional irregular shelterwood managed forest, and an irregular-shaped natural gap and part of the stand were selected in a semi-natural forest. Soil moisture, throughfall, and stemflow were measured in the gaps and stands, and incident precipitation was monitored in the open area. Evapotranspiration and drainage water fluxes were estimated using the water balance model BROOK90. To estimate drought stress, the ratio between simulated actual and potential evapotranspiration was used. Precipitation in the 2001 and 2003 growing seasons was considerably less than that in 2002 and 2004. The highest drainage fluxes were in the newly created clear-cut gaps with sparse ground vegetation cover, followed by the natural gap and medium gap, which had older and denser natural tree regeneration. On average, the clear-cut gap drainage fluxes were 18% (164?mm) higher than those in the forest stands. Evapotranspiration was lower in the natural gap and higher in the managed gap compared with the experimental clear-cut gaps. Water supply stress was greater for the forest stands than for the vegetation in the gaps. Drought stress was indicated to be lowest in the natural gap, which had patches of varying development phases and the highest water storage capacity of the soil and vegetation.     

A flexible unmanned aerial vehicle for precision agriculture

An unmanned aerial vehicle (??VIPtero??) was assembled and tested with the aim of developing a flexible and powerful tool for site-specific vineyard management. The system comprised a six-rotor aerial platform capable of flying autonomously to a predetermined point in space, and of a pitch and roll compensated multi-spectral camera for vegetation canopy reflectance recording. Before the flight campaign, the camera accuracy was evaluated against high resolution ground-based measurements, made with a field spectrometer. Then, ??VIPtero?? performed the flight in an experimental vineyard in Central Italy, acquiring 63 multi-spectral images during 10?min of flight completed almost autonomously. Images were analysed and classified vigour maps were produced based on normalized difference vegetation index. The resulting vigour maps showed clearly crop heterogeneity conditions, in good agreement with ground-based observations. The system provided very promising results that encourage its development as a tool for precision agriculture application in small crops.     

White clover selected for enhanced competitive ability widens the compatibility with grasses and favours the optimization of legume content and forage yield in mown clover‐grass mixtures

White clover‐grass mixtures should provide swards with a high dry matter (DM) yield with a clover proportion of at least 0·30. This study assessed the compatibility of one white clover variety selected for competitive ability (Giga) and four other large‐leaved clover varieties (Aran, Espanso, Fantastico and Regal) in mown binary mixtures with each of four grass companions (cocksfoot cv. Padania, hybrid ryegrass cv. AberExcel, Italian ryegrass cv. Crema, and tall fescue cv. Magno) over 3 years in northern Italy. On average, the mixtures including Giga had at least a two‐fold greater clover proportion in the total harvested DM (P < 0·01) and contained fewer weeds (P < 0·10) than those with other clover varieties, and also tended to have the highest total DM yields. On average, mixtures containing AberExcel had clover proportions of >0·25 but gave the lowest total DM yields, whereas those of Magno maximized total DM and had a higher proportion of clover than Padania or Crema. No clover × grass interaction was detected (P > 0·05). The association with Giga allowed the tall fescue‐based mixture to attain a clover proportion 0·331 along with a top‐yielding total DM. This mixture, compared with the only one without Giga that displayed a near‐sufficient clover proportion (Espanso with AberExcel), exhibited a 21·7% higher total DM (P < 0·05) and had far fewer weeds.     

Mating disruption of California red scale,Aonidiella aurantii Maskell (Homoptera: Diaspididae), using biodegradable mesoporous pheromone dispensers

BACKGROUND: The control of California red scale, Aonidiella aurantii (Maskell), has encountered many difficulties, which has raised interest in alternative control methods. Up to now, the A. aurantii sex pheromone has been used only for monitoring. In a previous work the authors described a biodegradable mesoporous pheromone dispenser for mating disruption. To verify the efficacy of these dispensers, three field trials were conducted, and the results are shown in this paper. RESULTS: The study of the release profile of these dispensers revealed a mean pheromone emission value of 269 µg day^?1 and levels of residual pheromone of 10% at the end of 250 days. During the second flight, an A. aurantii male catch reduction of 98% was achieved in the mating disruption plot of trial 1, 93.5% in trial 2 and 76.7% in trial 3. During the third flight, reductions were 94.1, 82.9 and 68.1% in trials 1, 2 and 3 respectively. Considering damaged fruit with more than five scales, reductions of about 80 and 60% were obtained in the mating disruption plots of trials 2 and 3, respectively, compared with an untreated plot, and a reduction of about 70% in trial 1 compared with an oil‐treated plot. CONCLUSION: Mating disruption has been found to be an efficient technique to control this pest, working equally well to a correctly sprayed oil treatment. Further studies are needed to improve the determination of the time of dispenser application and evaluate the effects of the pheromone on natural enemies. Copyright © 2010 Society of Chemical Industry     

Molecular characterisation of vegetative compatibility groups in Fusarium oxysporum f. sp. radicis-lycopersici and f. sp. lycopersici by random amplification of polymorphic DNA and microsatellite-primed PCR

Random amplification of polymorphic DNA (RAPD-PCR) analysis was conducted on 48 isolates of Fusarium oxysporum f. sp. radicis-lycopersici (F.o.r.l.) from different geographic regions, representing all known vegetative compatibility groups (VCGs) except VCG 0097 and VCG 0099 and on eight isolates of F.oxysporum f. sp. lycopersici (F.o.l.), representing VCGs 0030, 0031, 0032 and 0033. Upon UPGMA (unweighted pair-group method with arithmetic averages) analysis of 86 RAPD-PCR markers generated by 16 informative primers and 44 markers obtained with eight microsatellite primers, a close relatedness was evident for F.o.r.l. isolates in VCGs 0090, 0092, 0096, and, to a lesser extent, for those in VCG 0093. Representatives of VCG 0091 formed a distinct group, while F.o.r.l. isolates in VCGs 0094 and 0098 were not distinguishable by the tested markers, most of which were also shared by F.o.l. isolates belonging to VCGs 0031 and 0033. F.o.l. isolates in VCGs 0030 and 0032 shared most of the molecular markers. The correlation between RAPD-PCR and microsatellite genetic distance was highly significant (R² = 0.77; P by Mantel test < 0.001). The molecular variability observed in both formae speciales is discussed in relation to the development of F.o.r.l.- and F.o.l.-specific diagnostic tools.     

Experimental trial in heifers vaccinated with Staphylococcus aureus avirulent mutant against bovine mastitis

Staphylococcus aureus, is the most frequently isolated pathogen from cases of bovine mastitis. Vaccination against S. aureus seems to be a rational approach for the control of staphylococcal mastitis. In the present work we evaluate the response of heifers vaccinated with a S. aureus avirulent mutant to the intramammary challenge with a S. aureus virulent strain. Clinical signs, production of milk, shedding of S. aureus cells, somatic cell count (SCC) and antigen-specific IgG in blood and milk, were determined. Two subcutaneous doses of a culture of the mutant, used as vaccine, was administered to four pregnant heifers 30 and 10 days before calving. The vaccinated heifers and four non-vaccinated were challenged 10 days after calving with the homologous virulent S. aureus strain, which was inoculated by intramammary route into two quarters of each animal. No local tissue damage was observed due to the administration of the vaccine. A significantly increase of specific IgG to S. aureus RC122 was detected in blood and milk of vaccinate heifers as well as a slight increase in daily milk yield during the trial. No significant difference on shedding of bacteria in milk and SCC were found among groups. In conclusion, vaccination of heifers before calving by an avirulent mutant vaccine of S. aureus, induced specific and significant antibody responses and provide better post-challenge conditions in vaccinated heifers.     

The occurrence of phosphoenolpyruvate carboxykinase (PEPCK) in the pericarp of different grapevine genotypes and in grape leaves and developing seeds

The occurrence of phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate orthophosphate dikinase (PPDK) was determined in the ripe pericarps of several grape genotypes. Moreover, the abundance pattern of PEPCK during the development of grape berries was studied in a range of cultivars. In addition, the presence of PEPCK in grape leaves and the location/abundance of PEPCK in developing grape seeds were investigated. PEPCK was present in the pericarp of all the cultivars of Vitis vinifera studied and in that of the hybrid 420A (Vitis berlandieri × Vitis riparia). By contrast, PPDK was either not present or present at very low abundance. The results strongly indicated that the PEPCK and not the PPDK pathway is the predominant one utilised in gluconeogenesis in the berry pericarp of grape genotypes. Further, the results showed that the abundance of PEPCK increased greatly at the start of ripening in all the cultivars, showing a similar pattern in all of them. PEPCK was not present (or at very low abundance) in grape leaves throughout their development. In developing grape seeds, the results indicated a similar abundance of PEPCK in both the seed coat and the tissues enclosed by it.