Susceptibility of ostrinia nubilalis to bacillus thuringiensis var. kurstaki

Baseline susceptibility of European corn borer larvae, Ostrinia nubilalis (Hübner), to a commercial formulation of Bacillus thuringiensis var. kurstaki was determined for different strains in 7 geographic locations in the corn area of North Italy (Po Valley). For the bioassay 7 different doses, raised on a meredic diet, were used and the data was analysed with the Probit analysis. Differences in the susceptibility among the northern Italian populations of O. nubilalis were recorded, which can be attributed to natural variability. The ECB collected near Como and Torino was the most susceptible, respectively with LC50 of 0.23 and 0.57 mg/ml. The most tolerant ones were the larvae coming from the area of Vicenza (LC50 = 3.40 mg/ml). Baseline susceptibility was also determined for one population originally from Iowa but reared for more than 20 years in the laboratory and which had never experimented Bt. The LC50 calculated for this last one was compared to the Italian situation

Evaluation of phenolic composition and biological activity of honey

Honey is a natural food largely known as a sweetener, produced by Apis mellifera bees by collecting nectar from flowers. The use of honey in the treatment and prevention of numerous diseases such as respiratory disorders has been known since ancient times. It has been well documented the role of oxidative stress in many diseases and several studies demonstrated that honey contain a great number of metabolites that can scavenge free radicals. In this study, we investigated and compared phenolic content, antioxidant capacity and in vitro biological activities of multifloral commercial and artisanal Italian honey samples. Total phenolic content and radical-scavenging activity were analysed by Folin-Ciocalteu reagent and by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays, respectively. Phenolic compounds were extracted using Amberlite XAD-2 resin and a RP-HPLC method involving gradient elution and UV detection was applied to their separation [1]. The antimicrobial activity of the phenolic extracts was tested by means of a luminescence bacterial biosensor [2]. A strain of Streptococcus pyogenes isolated from human throat containing a firefly luciferase reporter gene was incubated with the honey phenolic fractions. A luminometer was used to quantify bioluminescence, which is directly connected to the cell metabolic state. The results demonstrated remarkable difference in bioactivity properties of honey from different sources. Total phenolic content, antioxidant and antibacterial activities were higher in artisanal honey samples, suggesting their richness in bioactive compounds that might exert potential health-promoting effects and increase its nutraceutical value. Acknowledgements: Dipartimento di Agronomia Ambientale e Produzioni Vegetali, Università di Padova, AGRIPOLIS, Viale dell'Università n. 16, 35020 Legnaro (PD), Italia, Prof. Stefano Bona, Dr.ssa Sara Sandrini. References: [1] Küçük, M. et al. (2007) Food Chem. 100:526-534. [2] Wilson, T. et al. (1998) Annu. Rev. Cell Dev. Bi. 14:197-230

Comments on the dynamics of insect population assemblages and sampling plans for aphids in commercial alpine yarrow fields

Achillea collina Becker ex Rchb. (yarrow) is a medicinal plant grown for commercial purposes in southern Switzerland and northern Italy. The economically most relevant population assemblage is organized around the phloem feeding aphids Macrosiphoniella millefolii (De Geer), Aphis spiraecola Patch and Coloradoa achilleae Hille Ris Lambers. The study is a contribution to explaining the dynamics of this assemblage in two Alpine fields, on the basis of multitrophic population interactions. The method consisted in stratifying the field and taking random samples of yarrow stems and leaves, aphid numbers, and numbers of adult coccinellids and mummified aphids throughout the growing period. There were no significant differences in aphid densities between the strata (\u3b1 = 0.05; F = 1.561; P = 0.138). Once the photoperiod reaches 14 h, a time window opens for stem elongation and reproductive development that creates suitable conditions for the aphids. There are indications for an influence of the plant and a possibly limited effect of natural enemies on aphid infestations. The coefficients b (1.920, 1.917) and a (3.911, 14.539) of Taylor's power law indicate aggregated distributions of M. millefolii and A. spiraecola. To obtain a reliable density estimate, 100 or 400 plants should be sampled for M. millefolii and A. spiraecola, respectively. An enumerative sequential sampling plan appears to be more efficient than the enumerative fixed sample size sampling plan

On the transmissibility of PPV by Myzus varians Davidson (Homoptera: Aphididae) to Clematis vitalba L. (Ranunculaceae)

Sharka is one of the most important diseases of stone fruits in Europe and plum pox virus (PPV) is its causal agent. Nowadays, such disease represents a major constraint for the production of peach fruits in Italy. Moreover, such virus systematically infects several herbaceous plants and more than 20 aphid species are known to be able to transmit the disease. Among them, M. varians has become an increasingly severe pest of peach orchards in Italy; its secondary food plants are Clematis spp. Therefore, we carried out specific experiments to verify the capacity of C. vitalba to host the virus. M. varians have been allowed to feed upon on PPV (serotype M) infected peach plants (GF305) and placed in plants in small glasshouses together with healthy C. vitalba plants thus only the alates could reach the herbaceous plants, reproducing the natural cycle of the peach-clematis aphid. A reverse transcription polymerase chain reaction (RT-PCR) assay was applied to detect the presence of PPV in C. vitalba plants. The obtained results confirm the transmission of PPV from peach to C. vitalba by alates of M. varians. This paper reports also, for the first time, that C. vitalba is a suitable alternative host for PPV-M virus serotype

Comparative evaluation of VOCs emitted by Achillea collina infested by aphids and mechanically damaged

Plants along the centuries evolved wide range of mechanisms to cope with biotic and abiotic stresses, including the emission of induced volatile organic compounds (VOCs), whose production is trigged by mechanical damage or pathogen infestation of plant tissues, providing them defensive tools (Arimura et al. 2005). This study focuses on VOCs emitted by Achillea collina Becker ex Rchb. as a results of aphid infestation and mechanical damages. In particular it takes account of differences between compounds induced by the generalist Myzus persicae (Sulzer), the specialist Macrosiphoniella millefolii DeGeer aphid species infestation and two different types of mechanical injury (pin shoot and extended pressure). Headspace Solid-Phase-Microexctraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC/MS) \u201cin vivo\u201d method was used to evaluate A. collina VOCs. We observe, in both aphids infestation a decrease of trans-2-hexenal associate with an increase of 2-hexen-1-ol and 1-hexanol, suggesting the activation of the methabolic pathway that leads to production of green leaf volatile compounds (Gatehouse 2002). The same result was recorded in mechanically induced damages suggesting that in A. collina the production of these compounds is a non specific response to induced both by mechanically and aphids provoked injuries. Furthermore a decrease of some terpenes (\u3b2 and \u3b3-pinene) and the increase of others (\u3b1-phellandrene and isocaryophyllene) were recorded. The involvement of significantly varying compounds in tritrophic interaction mechanisms is also discussed

Barcoding chrysomelidae: a resource for taxonomy and biodiversity conservation in the Mediterranean Region

The Mediterranean Region is one of the world’s biodiversity hot-spots, which is also characterized by high level of endemism. Approximately 2100 species of leaf beetle (Coleoptera; Chrysomelidae) are known from this area, a number that increases year after year and represents 5/6% of the known species. These features, associated with the urgent need to develop a DNA-based species identification approach for a broad spectrum of leaf beetle species, prompted us to develop a database of nucleotide sequences, with a solid taxonomic background, for all the Chrysomelidae Latreille, 1802 sensu latu inhabiting the Mediter­ranean region. The Mediterranean Chrysomelidae Barcoding project, which has started in 2009, involves more than fifty entomologists and molecular biologists from different European countries. Numerous collecting campaigns have been organized during the first seven years of the project, which led to the collection of more than 5000 leaf beetle specimens. In addition, during these collecting campaigns two new allochthonous species for Europe, namely Ophraella communa LeSage, 1986 and Colasposoma dauricum Mannerheim, 1849, were intercepted and some species new to science were discovered (e.g., Pachybrachis sassii Montagna, 2011 and Pachybrachis holerorum Montagna et al., 2013). DNA was extracted from 1006 specimens (~13% of the species inhabiting the Mediterranean region) and a total of 910 cox1 gene sequences were obtained (PCR amplification efficiency of 93.8%). Here we report the list of the bar­coded subfamilies, genera and the number of species for which cox1 gene sequences were obtained; the metadata associated with each specimen and a list of problematic species for which marker amplification failed. In addition, the nucleotide divergence within and between species and genera was estimated and values of intraspecific nucleotide divergence greater than the average have been discussed. Cryptocephalus quadripunctatus G. A. Olivier, 1808, Cryptocephalus rugicollis G. A. Olivier, 1791 and Exosoma lusitanicum Linnaeus, 1767) are representatives of these cases