Geographical cline of DNA variation within the F intersterility group of Heterobasidion annosum in Italy

Eighty-six Heterobasidion annosum isolates, mainly belonging to the F intersterility group and obtained from 32 different geographical localities in Italy, were subjected to genetic analysis by the Random Amplified Polymorphic DNA (RAPD) markers. The similarity between F and S groups was higher than that between F and P. In UPGMA Cluster Analysis, the F isolates originating from the same locality usually grouped in the same cluster. The isolates also showed a tendency to group at the level of larger geographical areas. Within the F group, isolates from the south of the Italian peninsula showed the highest genetic variation and northern isolates from the Alpine regions showed the lowest. This indicates a gradual cline along the peninsula. The genetic variability in the Italian F group is discussed in relation to the past and present distribution of the host species in Italy and Europe.     

Emergence of tomato leaf curl New Delhi virus in Italy: estimation of incidence and genetic diversity

Tomato leaf curl New Delhi virus (ToLCNDV) is a bipartite begomovirus (family Geminiviridae) identified for the first time in 1995 in Asia, from where it spread into several countries of the Mediterranean basin. ToLCNDV was found in Spain in 2012, and subsequently in Tunisia and Italy. The first outbreak in Italy occurred at the end of 2015 in Trapani province (Sicily) on zucchini squashes. Then in 2016, ToLCNDV was found in infected zucchini plants in Campania, Lazio and Sardinia regions, and in 2017 in Calabria. This study addressed the dispersion and genetic diversity of ToLCNDV isolates in Italy. A total of 1400 plants were analysed. Phylogenetic analysis showed low variability among the Italian isolates, probably as a consequence of the recent introduction and rapid spread of this virus in Italy. Two statistically significant clusters were reported: one grouping only Italian isolates and the other grouping Italian, Spanish, Tunisian and Moroccan isolates. Furthermore, the highest incidence of ToLCNDV was observed in Sicily, although the disease also appears to be critical in other Italian regions. In this work, a high efficiency of ToLCNDV mechanical transmission into Cucurbita pepo, Cucumis melo inodorus and Cucumis melo cantalupensis has been demonstrated. The rapid spread of ToLCNDV in the Mediterranean basin represents a threat for horticultural production, thus it is very important to develop suitable crop management practices, applying genetic resistance strategies and more restrictive phytosanitary measures.     

Evolutionary analysis of Citrus tristeza virus outbreaks in Calabria,Italy: two rapidly spreading and independent introductions of mild and severe isolates

The evolution of citrus tristeza virus (CTV) from outbreaks occurred in Calabria, Italy, was compared with that of CTV outbreaks reported previously in another two proximal Italian regions, Sicily and Apulia. Examination of four genomic regions (genes p20, p25 and p23, and one fragment of open reading frame 1) showed two recombination events, and phylogenetic analysis disclosed two divergent CTV groups in Calabria: one formed by severe and the other by mild isolates. This analysis, together with others involving population genetic parameters, revealed a low migration rate of CTV between the three Italian regions, as well as significant differences in selective pressures, epidemiology and demography, all affecting the genetic structure of CTV populations.     

Population dynamics and spread of Unaspis yanonensis in Calabria, Italy

The occurrence of Unaspis yanonensis (Kuwana) (Hemiptera: Diaspididae) in Calabria (southern Italy) poses a serious threat to citrus cultivation. A regional survey was performed to record information about its distribution in local citrus orchards. Field population dynamics were also studied. The arrowhead scale, U. yanonensis, was recorded in the two main citrus cultivation areas of Calabria. In the investigated environments U. yanonensis completed two generations per year; a typical bi-modal oviposition was recorded. The arrowhead scale overwintered as second-instar males and pre-ovipositing females.     

Noctuid Species Causing Damage to Maize in Turkey1

In Turkey, maize is grown in the Black Sea, Marmara and Aegean Regions as well as in the southern part of the country, with a total area of 600,000 ha. Control measures againsts pests play an important part in maize production. Noctuid species are important maize pests in Turkey, and the following species occur: Scotia ipsilon, Scotia segetum, Sesamia nonagrioides, Sesamia cretica, Mythimna loreyi, Mythimna unipuncta, Spodoptera exigua. Research on the ecology of S. ipsilon is being conducted in the Black Sea Region. This species passes through 4 to 5 generations annually. In recent years, S. nonagrioides has been found in the Aegean Region and studies on this pest have started. S. cretica is widely distributed in the Marmara, Mediterranean and South-eastern Regions of Turkey. This species produces two generations annually. M. loreyi and M. unipuncta cause damage only in limited areas. Helicoverpa armigera and S. exigua are widely distributed throughout the maize-growing regions, but cause considerable damage only in limited areas.     

Infections of Glomerella cingulata on olive in Italy1

Olive anthracnose, caused by strains or populations of Glomerella cingulata (anamorph Colletotrichum gloeosporioides) pathogenic for olive, was introduced into southern Italy before or during the 2nd World War presumably from Albania or Greece. In the following 20 years, severe outbreaks of fruit rot and dieback of twigs and branches were recorded in several areas of Puglia, Calabria, Sicilia and Sardegna. After the 1970s, the epidemics gradually regressed. At present, the disease is restricted to certain humid areas of southern Italy. Factors associated with this regression are discussed, including a supposed change in virulence of the fungus, possibly as a consequence of mixing of the introduced strains infecting olive trees with local, less pathogenic populations of G. cingulata. The first results of a comparison of olive isolates with isolates of the pathogen from citrus and Annona muricata in Calabria suggest that the population from olive is relatively homogeneous and can be distinguished from the population infecting other hosts by a number of morphological, pathogenic and biochemical characteristics.     

Phytophthora species causing crown and root rot of tomato in southern Italy*

Phytophthora capsici, Phytophthora cryptogea and Phytophthora nicotianae were isolated from tomato plants with symptoms of crown and root rot in plastic‐house crops in Sicilia and Calabria (southern Italy). The species were identified primarily on the basis of morphological and cultural characteristics. The identification was confirmed using molecular methods, polyacrylamide gel electrophoresis (PAGE) of mycelial proteins and polymorphism of DNA sequences amplified by polymerase chain reaction using random primers (RAPD‐PCR). P. capsici caused significant losses in tomato crops that had succeeded capsicum crops. P. cryptogea was found to be the most frequent species causing basal stem rot of tomato, a disease of increasing importance in commercial tomato crops in plastic houses in Sicilia. P. nicotianae was common in plastic houses where poor drainage resulted in standing water.     

Detection and Identification of <Emphasis Type="Italic">Phytophthora</Emphasis> Species in Southern Italy by RFLP and Sequence Analysis of PCR-amplified Nuclear Ribosomal DNA

In four neighbouring regions of southern Italy, Basilicata, Campania, Apulia and Calabria, pepper and zucchini plants showing Phytophthora blight symptoms, tomato plants with either late blight or buckeye rot symptoms, plants of strawberry showing crown rot symptoms and declining clementine trees with root and fruit rot were examined for Phytophthora infections by means of polymerase chain reaction (PCR) assays, using primers directed to nuclear ribosomal DNA (rDNA) repeat sequences. All diseased plants and trees examined tested positive. The detected fungal-like organisms were differentiated and characterized on the basis of primer specificity as well as through extensive restriction fragment length polymorphism (RFLP) and sequence analysis of PCR-amplified rDNA. Phytophthora capsici was identified in diseased pepper and zucchini plants, P. infestans was identified in tomato with late blight symptoms whereas buckeye rot-affected tomatoes and diseased strawberry plants proved to be infected by P. nicotianae and P. cactorum, respectively. Declining clementine trees were infected with P. citrophthora and P. nicotianae in about the same proportion. Also, thirty-one pure culture-maintained isolates of Phytophthora which had previously been identified in southern Italy by traditional methods but were never examined molecularly, were examined by RFLP and sequence analysis of PCR-amplified nuclear rDNA. Among these, an isolate from gerbera which had previously been identified by traditional methods only at genus level, was assigned to P. tentaculata. For the remaining pure culture-maintained isolates examined, the molecular identification data obtained corresponded with those delineated by traditional methods. Most of the diseases examined were already known to occur in southern Italy but the pathogens were molecularly detected and fully characterized at nuclear rDNA repeat level only from other geographic areas, very often outside Italy. A new disease to southern Italy was the Phytophthora blight of zucchini. This is also the first report on the presence and molecular identification of P. tentaculata from Italy.     

Hymenoptera wasps associated with the Asian gall wasp of chestnut (Dryocosmus kuriphilus) in Calabria,Italy

The parasitoid complex of the Asian chestnut gall wasp Drycosmus kuriphilus Yasumatsu was studied in Calabria (Italy). A total of 14 different species of parasitoids were collected, of which three are recorded on the Asian gall wasp for the first time. The composition of the parasitoid complex collected in Calabria was compared with that reported from Italy and from Europe. The altitude of the sites of collection seemed to have an effect on the distribution and abundance of the single species of parasitoids.     

Sequence and simple-sequence repeat analyses of the fungal pathogen Seiridium cardinale indicate California is the most likely source of the cypress canker epidemic for the Mediterranean region

Seiridium cardinale is the pathogenic fungus of unknown origin responsible for a world pandemic known as cypress canker affecting several species of Cupressaceae in both the Northern and Southern Hemisphere. In this study, a comparative genetic analysis of worldwide populations was performed using sequence analysis of a portion of the ?-tubulin locus and seven polymorphic simple-sequence repeat (SSR) loci on 96 isolates. Sequence analysis identified two distinct ?-tubulin alleles, both present in California. Only one of the two alleles was detected in the Mediterranean basin, while two isolates from the Southern Hemisphere were characterized by the presence of the allele absent from the Mediterranean. SSRs identified a total of 46 multilocus genotypes (MGs): genotypic diversity was always higher in the California population, and calculations of the index of association (I(A)) determined the presence of linkage disequilibrium associated with the absence of sexual reproduction only in the Mediterranean population but not in California. In 50 instances, the same MG was found at great geographic distances, implying a role played by humans in spreading the disease. Network analysis performed on SSR data identified three clusters of MGs: California, Morocco, and the rest of the Mediterranean. Both the Morocco and the Mediterranean clusters were linked to the California cluster. Coalescent analysis identified insignificant migration between California and Italy, as expected in the presence of a single introduction event, and very high migration from Italy into Greece, as expected of an outbreak still in exponential growth phase and starting from an Italian source.     

Site‐specific reproductive performance of an invasive fleshy‐fruited tree in remnant grasslands of the Argentinean Pampas

Prunus mahaleb (Saint Lucie's cherry) is a fleshy‐fruited small rosaceous tree, native to the Mediterranean region that has been extensively used as a rootstock species for commercial orchard trees. It has been widely introduced in several countries, becoming invasive in many regions, including the Pampas region of southern Argentina. We studied the reproductive performance of trees spontaneously growing in natural grasslands inside a protected area, estimating age at first reproduction and analysing changes in fruit production, age, canopy volume and basal stem diameter associated with different soil types: rock crevices on hillsides, deep soils in valleys and deep soils in stream‐side habitats. Fruit production starts at the age of 3–6 years, and it can be abundant, even for young plants. We found evidence that fecundity is related to plant size, and that the age at which individuals reach a particular size and begin fruiting differs depending on the soil type where they grow. Trees in the study area show an order of magnitude increase in fruit production on reaching ages from 7 to 10 years for plants growing in deep soils at stream‐side habitats and 13–16 years for plants growing in rock crevices. Invasive trees should be felled before they reach a basal stem diameter of c. 9 cm to avoid this increase in propagule pressure. Considering that the age at which this stage is reached depends on soil type, the streams could act as dispersal corridors for the spread and invasion of this species.     

Mycelial compatibility groups and pathogenic diversity in Sclerotium rolfsii populations from sugar beet crops in Mediterranean‐type climate regions

The population structure of Sclerotium rolfsii from autumn‐sown sugar beet crops in Mediterranean‐type climate regions of Chile, Italy, Portugal and Spain was determined by analyses of mycelial compatibility groups (MCGs) and pathogenicity to 11 economically important plant species. Twelve MCGs (i–xii) were identified among 459 S. rolfsii isolates. MCG iii was the most prevalent group in all countries except Italy. MCG i, the most abundant group (64·7% of isolates) was identified in Portugal and Spain. The remaining MCGs were restricted to various regions within one country (ii, vi, ix) or different countries (v), or to specific localities (iv, vii, viii, x, xi, xii). MCGs iv, vii and x each comprised one isolate. Fields extensively sampled in southern Spain were infected with one to three MCGs. Plant species differed in susceptibility to MCG tester isolates with a MCG by species interaction. Cluster analyses allowed selection into five MCG groupings and grouped plant species into species‐groups 1 (broccoli, chickpea, sunflower, tomato) and 2 (cotton, pepper, sugar beet, watermelon). MCG groupings 1 (i, ix), 2 (ii, iii, vi, viii) and 5 (x, xii) were moderately virulent to species‐group 1 and mildly virulent to species‐group 2. MCG groupings 3 (iv, v, xi) and 4 (vii) were mildly virulent to both species‐groups. Across MCG groups, species were rated highly susceptible (chickpea, sunflower), susceptible (cotton, pepper, tomato, watermelon), moderately resistant (broccoli, melon, sugar beet) and resistant (corn, wheat). Establishing the MCG population structure and virulence variability among S. rolfsii isolates should help in the management of sclerotium root rot diseases.     

Molecular characteristics of phytoplasmas associated with Flavescence dorée in clematis and grapevine and preliminary results on the role of Dictyophara europaea as a vector

A survey was conducted over several years in Italy and the Balkans in order to gain an understanding of the relationship between the Flavescence dorée (FD) phytoplasma isolates found in clematis and grapevine. A total of 399 clematis and 107 grapevine samples were analyzed. The results showed that 36% of the Clematis vitalba plant samples were infected by phytoplasmas which, in grapevine, are associated with FD, a quarantine disease in Europe. Infected clematis plants were also found in areas where FD phytoplasma had never previously been reported to infect grapevine, such as Macedonia, Croatia and some areas of Italy and Serbia. Molecular data from three phytoplasma genomic fragments showed the presence of different FD phytoplasma isolates, all belonging to the 16SrV-C subgroup, including the Italian FD-C isolate, the isolate found in Serbia, an isolate similar to the French FD2000 and a new isolate typical of central Italy. A few clematis plants were infected with single nucleotide polymorphism, insertion or deletion mutants of the FD-C isolate. Of all the potential Hemipteran vector species surveyed in Italy and Serbia, only 18 of 527 Dictyophara europaea individuals tested proved to be infected with the FD phytoplasma. Preliminary transmission experiments showed that this species is able to transmit the FD phytoplasma from clematis to grapevine. The presence of FD-infected clematis and of D. europaea could, therefore, constitute a risk for FD epidemics in the European viticultural regions.     

Pest risk analysis for Solanum elaeagnifolium and international management measures proposed

Solanum elaeagnifolium Cav., originating from the Americas, has been unintentionally introduced in all the other continents as a contaminant of commodities, and is considered one of the most invasive plants worldwide. In the Euro‐Mediterranean area, it is a huge threat in North African countries. It is also present in European Mediterranean countries (France, Greece, Italy and Spain), but still has a limited distribution. Through a logical sequence of questions, pest risk analysis (PRA) assessed the probability of S. elaeagnifolium entering, establishing, spreading and having negative impacts in European and Mediterranean countries. As this assessment revealed that the entry of the pest would result in an unacceptable risk, pest risk management options were selected to prevent the introduction of the plant. Preventive measures on plants or plant products traded internationally may directly or indirectly affect international trade. According to international treaties, PRA is a technical justification of such international preventive measures.     

European Field Voles of the Genus Pitymys McMurtrie and their Damage in Agriculture,Horticulture and Forestry1

Research has been carried out to establish the actual incidence in European agriculture and forestry of damage by voles belonging to the genus Pitymys McMurtrie. Unfortunately, the great uncertainty remaining in the taxonomy of these voles and the practical difficulty of recognizing the species responsible for specific damage do not allow us to form, as yet, a complete picture of the situation. Nevertheless, it has been shown that, in Europe, Pitymys voles which are responsible for damage to agricultural crops (irregularly and with varying intensities) can, essentially, be placed in one of the following fundamental species groups:subterruneus (de Sélys Longcharnps), savii (de Séys Longchamps) or duodecimcostutus (de Sélys Longchamps). Without doubt, greatest damage appears to be done by voles of the species group savii which, in a decidedly more southern distribution area, brings about serious damage, particularly to horti-floricultural crops in the Italian peninsula. In Italy, where the Pitymys problem is perhaps more noticeable than anywhere else, the control methods used tend to be inefficacious and do not answer the problem. We hope, therefore, besides conducting a comprehensive biological study of this species group, to carry out adequate experimentation towards developing methods for testing the latest rodenticides as to their efficacy against Pitymys and to develop an adequate application technique.     

Rare and endangered plant species of the Chinese Altai Mountains

Altai (also named Altay in China) Mountain Country (Mountain System) is a unique natural region,located on the border between different floristic regimes of the Boreal and ancient Mediterranean sub-kingdoms,where distribution of plant species is actually limited. It is known to have sufficient endemic floral biodiversity in the Northern Asia. Many plants of Altai Mountain System need effective care and proper conservation measures for their survival and longer-term protection. Important Plant Area identified as the IUCN (the International Union for Conservation of Nature),specified criteria attract global attention for protection of floral biodiversity across the world. The records of 71 plant species from the Chinese Altai Mountains attributed to the criterion A and the dark conifer forests of Chinese Altai Mountains satisfied the criterion C,which may help qualify to fulfill the national obligation of the Convention on Biological Diversity.     

First data on the flight activity and distribution of the ambrosia beetle Xylosandrus compactus (Eichhoff) on carob trees in Sicily

The factors influencing the entry and the spread of the black twig borer, Xylosandrus compactus (Eichhoff), in the Mediterranean environment have not yet been characterized. Following its first report in Sicily (southern Italy) in 2016, and due to the high level of damage it causes on one of its host plants (Ceratonia siliqua L.), the flight activity of the pest was studied there. Monitoring was performed from spring 2017 to summer 2018 by exposing red cross‐shaped sticky traps combined with ethanol‐baited bottle traps. The three monitored sites were selected at different altitudes, representing the southern Mediterranean environment where the carob tree is widely present. The results showed that the pest populations are influenced by climatic factors. In particular, the first adults were caught when the maximum daily temperatures were stably higher than 20°C over several continuous days. Xylosandrus compactus occurred widely in the monitored territory and was continuously caught from spring to autumn. Furthermore, the traps used proved to be effective for intercepting the spring flight of the overwintering females. Moreover, the ability of the beetle to spread from a new infested area was also studied. It seems that the pest can spread more than 8 km from the last infested site of the previous flying season. It was not present above altitudes of 400 m in the conditions of the present study. This study represents the first step to better understand the behaviour of X. compactus in a newly colonized environment.     

Incidence of ‘Candidatus Liberibacter europaeus’ and phytoplasmas in Cacopsylla species (Hemiptera: Psyllidae) and their host/shelter plants

Psyllids, as vectors of phloem-restricted plant pathogens, are serious agricultural pests. Fruit tree phytoplasmas are transmitted by different Cacopsylla spp., while other psyllids are known vectors of liberibacters. Recently, the bacterium ??Candidatus Liberibacter europaeus?? was found in pear trees and in Cacopsylla pyri (Linnaeus), the vector of ??Ca. Phytoplasma pyri??. This new species does not cause symptoms in plants and is probably a symbiont rather than a pathogen. Based on these findings and the assumption that ??Ca. Liberibacter europaeus?? is widespread, we studied its distribution in the genus Cacopsylla and in the respective host and shelter plants (where psyllids aestivate and overwinter), as well as its possible co-presence with ??Ca. Phytoplasma?? spp. We tested 14 Cacopsylla species and 11 plant species from northwestern Italy, Hungary and Israel, characterized by warm oceanic, temperate continental and warm Mediterranean climatic conditions, respectively. ??Ca. Liberibacter europaeus?? was common within the Cacopsylla genus, being present in nine of the 14 species screened as well as in most host plants, whereas none of the shelter plants tested positive for this bacterium. Altogether, these findings indicate the presence of ??Ca. Liberibacter europaeus?? in continental zones, whereas it does not seem to be widespread in the Mediterranean region. Furthermore, lack of specific symptoms in all infected plants confirms an endophytic relationship with this bacterium, while its abundance in insects suggests a beneficial role for the host. Co-infections with phytoplasmas, observed in insects and plants, require further study to evaluate the possible interactions between them.     

Genetic variability and population structure of <Emphasis Type="Italic">Grapevine virus A</Emphasis> coat protein gene from naturally infected Italian vines

Grapevine virus A (GVA) is considered one of the viruses associated with rugose wood (RW), one of the most economically important diseases of grapevine. Thirty-seven GVA isolates collected from grapevine cultivars from Marche (central-eastern Italy), Apulia and Campania (southern Italy), were subjected to molecular characterization. The genetic and population diversity was studied in the coat protein (CP) gene by RT-PCR-RFLP analysis with three restriction enzymes (MseI, AluI, and AciI), and nucleotide sequencing. A new primer pair (CP1F/R) allowing amplification of the whole CP gene (621 bp) was developed. RFLP with AciI yielded the highest number of variants in GVA isolates, showing seven different ‘simple’ profiles (A, B, C, D, E, F, and G). ‘Complex’ profiles were also found, and the most common variant combination was A + B in 39% of isolates. The analysis of GVA sequences confirmed the presence of plants infected with more than one GVA variant and suggested that RT-PCR-RFLP is suitable for evaluating population diversity of GVA enabling a screening of different haplotypes. The distribution of RFLP profiles and the phylogenetic analysis were not correlated with the location of infected plants, showing the presence of a GVA population with genetic diversity in the average with those of RNA viruses.