Pio Federico Roversi

Occurrence and transmission of mycovirus Cryphonectria hypovirus 1 from dejecta of Thyreophagus corticalis (Acari, Acaridae).

The natural spread of virus-induced hypovirulence is highly involved in the recovery of blighted chestnut stands and orchards in Italy and in Europe. The potential role of corticolous mites as vectors of hypovirulence in blighted chestnut Castanea sativa (Mill.) stands was pointed out in previous reports. Here, by using RT-PCR, mycovirus Cryphonectria hypovirus (CHV1) was detected in Thyreophagus corticalis mites reared on a hypovirulent strain in monoxenic cultures and in their faecal pellets. Cryphonectria parasitica mycelium derived from mites dejecta was able to transmit CHV1 to the virulent strain determining its conversion to hypovirulent one. This converted strain induced healing cankers on excised stems, differently from the un-converted virulent strain. Our findings prove the spread of CHV1 by corticolous mites that feed on virus-infected fungus and emphasize their potential role as vectors.

Computer-aided photographic identification of Rosalia alpina (Coleoptera: Cerambycidae) applied to a mark-recapture study

Assessing the conservation status of protected species needs quantitative population data, generally obtained using Capture‐Mark‐Recapture methods (CMR). The exploitation of natural marking (e.g. individual morphological traits) offers an interesting alternative, based on image analyses, which may result in a less manipulation of protected species compared to the typical artificial marking method. In our 2‐year CMR study, we tested for the first time in the natural setting the feasibility and the application of the computer‐aided photographic identification method of Rosalia alpina using the individual elytral spots as the natural marking. The I3SC software was used for the photographic analysis. Data were collected from populations of two National Parks of central Italy during July–August in 2014 and 2015. We developed a standard procedure in order to optimise the image acquisition in the field and to acquire clear and comparable images, facilitating the I3SC screening process. The results demonstrated that the computer‐aided photographic identification of natural markings can be implemented in a CMR population study of R. alpina. Our image processing approach showed that using only the elytral central spot contours made the tracing contour process less time‐consuming obtaining reliable results. Furthermore, I3SC output scores were used to identify a threshold value for the identification of new individuals or recaptures, facilitating the final identification proposed by operators. Finally, we assessed the possibility of performing the methodology using a Citizen Science approach.

Differential susceptibility of Popillia japonica 3rd instars to Heterorhabditis bacteriophora (Italian strain) at three different seasons

ABSTRACT The scarab beetle Popillia japonica, a pest native to northern Japan, has been recently found in Italy. Entomopathogenic nematodes are useful for biological control of this invasive insect. Previous work showed that 1st and 2nd larval stages are more susceptible to nematodes than 3rd instars. We tested the effectiveness of Heterorhabditis bacteriophora in the laboratory against P. japonica 3rd instars. Experiments were conducted in Italy with larvae field collected in the fall, winter and spring, showing a significant decrease in effectiveness from the fall to spring.

Lethal and sublethal effects of long-lasting insecticide-treated nets on the invasive bug Halyomorpha halys

Halyomorpha halys is a polyphagous insect species with an original eastern Asiatic distribution, which was recently and accidentally introduced in the USA and Europe, where it became a serious agricultural pest. Chemicals have been widely used for its control leading often to failure of IPM programmes. Several approaches aimed at pest monitoring and control are currently under investigation, for example trapping, screening, border management and biological control. In the present work, we investigated the lethal and sublethal effects of the use of a long‐lasting insecticide‐treated net (LLIN with α‐cypermethrin), focusing on the perspective to control H. halys in an integrated approach. All experiments were carried out in the laboratory either in small arenas, at five exposure times (5, 15, 30, 45 and 60 min) or in large cages at 8 hr exposure. In small arenas, the LLIN induced sublethal effects and/or effectively killed the adults. A higher adult mortality was observed after longer exposure times (LT90 was 51.64 min for females and 40.83 min for males). However, several specimens recovered from sublethal effects, with higher recovery rates after shorter exposure times. In the cage experiments, a significantly higher mortality (65% males and 75% of females) was recorded compared with controls. LLINs are physical barriers that can improve crop protection due to their insecticidal activity, and can be reasonably applied in various attract‐and‐kill systems both in glasshouses and in the field.

Hexamermis popilliae n. sp. (Nematoda: Mermithidae) parasitizing the Japanese beetle Popillia japonica Newman (Coleoptera: Scarabaeidae) in Italy

A new species of mermithid nematode, Hexamermis popilliae n. sp. (Nematoda: Mermithidae) is described from the Japanese beetle Popillia japonica Newman in Italy, an area of new introduction for this invasive pest. The combination of the following characters separates H. popilliae from other members of the genus Hexamermis Steiner, 1924: adult head obtuse; amphidial pouches slightly posterior to lateral head papillae in female but adjacent to lateral head papillae in males; amphidial openings large, well developed; amphidial pouches elliptical in females and oblong in males; cuticular vulvar cone well developed, vulvar lips greatly reduced or lacking, vagina curved at tip where meeting uteri, without reverse bend (not S-shaped), spicules slightly curved, with a slight bend in the basal portion, approximately equal to body width at cloaca. This is the first record of a species of Hexamermis parasitizing the Japanese beetle Popillia japonica. The only previous mention of mermithid nematodes from P. japonica was an undescribed species of Psammomermis in North America. Hexamermis popilliae will be evaluated as a potential biological control agent in an integrated control program of the Japanese beetle in Italy.

How ecosystems change following invasion by Robinia pseudoacacia : Insights from soil chemical properties and soil microbial, nematode, microarthropod and plant communities

Biological invasions are a global threat to biodiversity. Since the spread of invasive alien plants may have many impacts, an integrated approach, assessing effects across various ecosystem components, is needed for a correct understanding of the invasion process and its consequences. The nitrogen-fixing tree Robinia pseudoacacia (black locust) is a major invasive species worldwide and is used in forestry production. While its effects on plant communities and soils are well known, there have been few studies on soil fauna and microbes. We investigated the impacts of the tree on several ecosystem components, using a multi-trophic approach to combine evidence of soil chemical properties and soil microbial, nematode, microarthropod and plant communities. We sampled soil and vegetation in managed forests, comparing those dominated by black locust with native deciduous oak stands. We found qualitative and quantitative changes in all components analysed, such as the well-known soil nitrification and acidification in stands invaded by black locust. Bacterial richness was the only component favoured by the invasion. On the contrary, abundance and richness of microarthropods, richness of nematodes, and richness and diversity of plant communities decreased significantly in invaded stands. The invasion process caused a compositional shift in all studied biotic communities and in relationships between the different ecosystem components. We obtained clear insights into the effects of invasion of managed native forests by black locust. Our data confirms that the alien species transforms several ecosystem components, modifying the plant-soil community and affecting biodiversity at different levels. Correct management of this aggressive invader in temperate forests is urgently required.

A first assessment of genetic variability in the longhorn beetle Rosalia alpina (Coleoptera: Cerambycidae) from the Italian Apennines

Abstract The Rosalia longicorn (Rosalia alpina) is a strictly protected saproxylic beetle, widely distributed in Central and Southern Europe and mainly associated with ancient beech forests. To improve knowledge about the conservation status of R. alpina in Italy, available molecular markers (microsatellites and mitochondrial cytochrome c oxidase I(COI)) were tested for the first time on Italian populations. The study was performed in four sampling sites distributed in two areas placed in Northern (“Foreste Casentinesi” National Park) and Central Apennines (“Abruzzo, Lazio and Molise” National Park) where populational data about Rosalia longicorn were collected in the framework of the European LIFE MIPP Project. The genetic relationship among Apennine and Central/South-eastern European populations was explored by a comparison with mitochondrial DNA (mtDNA) data from literature. Microsatellite markers were only partially informative when applied to R. alpina Italian individuals, although providing some preliminary indication on an extensive gene flow among populations from the Apennines and local ongoing processes of genetic erosion. Genetic data are consistent with previous ecological data suggesting that the maintenance of variability in this species could be related to both habitat continuity and preservation of large senescent or standing dead trees in forests. Finally, a peculiar origin of the Apennine populations of R. alpina from a putative “Glacial Refugium” in Italy was inferred through COI data. The high genetic distance scored among the analysed populations and those from Central and South-eastern Europe indicates that the R. alpina deme from Apennine Mountains might represent a relevant conservation unit in Europe. Further genetic analyses will allow assessing other possible conservation units of R. alpina and, thus, defining large-scale conservation strategies to protect this endangered longhorn beetle in Europe.

Graphosoma lineatum (Hemiptera: Pentatomidae): a suitable host for mass rearing Ooencyrtus telenomicida (Hymenoptera: Encyrtidae)

ABSTRACT The species Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae) is currently being considered as a candidate for augmentative biological control agent (BCA) against several pests, including Halyomorpha halys (Stål) (Heteroptera: Pentatomidae). Protocols for mass production of a BCA need fundamental information on its biological attributes. Here we tested a possible laboratory host for the rearing of O. telenomicida: the common bug Graphosoma lineatum L. (Heteroptera: Pentatomidae). At tested conditions, O. telenomicida biological parameters were: rm 0.154, offspring production 84.07 specimens/female, sex ratio (% females) 71%, juvenile development time about 16 days, population doubling time 4.52 days, emergence rate about 90%.

Adaptive management of invasive pests in natural protected areas: the case of Matsucoccus feytaudi in Central Italy.

Invasive species are a significant threat to affected ecosystems, having serious environmental, economic and social impacts. The maritime pine bast scale, Matsucoccus feytaudi Ducasse (Hemiptera: Matsucoccidae), causes serious damage to Pinus pinaster forests in SE France, Corsica and Italy where it has been introduced. This study illustrates the adaptive management plan implemented in the Migliarino, San Rossore, Massaciuccoli Regional Natural Park in Tuscany, Italy, where M. feytaudi arrived in 2004, leading to the decay of local P. pinaster stands. The management programme, aimed at slowing the establishment and growth of M. feytaudi, was carried out in the main sector of the park, Tenuta di San Rossore, to retard the destruction of the P. pinaster coastal strip protecting the more internal woodland from sea salt and to allow replacement of P. pinaster trees with a more stable broad-leaved wood. The combined use of mass trapping and silvicultural interventions, applied in a targeted manner according to distribution maps of pest captures and damage, helped to delay forest destruction compared with a nearby unmanaged area of the park Tenuta di Tombolo. Although M. feytaudi continued to spread during the management period, the populations remained at low levels for 6 years, showing a marked increase in 2012. During this period, the P. pinaster stands were reduced from 320 to 249 ha. The final result of this ongoing gradual conversion process will be transformation of the P. pinaster forest into Holm oak woods and Mediterranean shrub land, while P. pinaster will survive as clusters or blocks of trees.

Entomopathogenic fungi and nematodes against larvae of the chestnut weevil, Curculio elephas (Coleoptera: Curculionidae): a laboratory evaluation

ABSTRACT Pest control in chestnut orchards is mainly achieved by chemicals, but there is growing focus on the potential use of biological control agents. The larval susceptibility of the chestnut weevil Curculio elephas L. (Coleoptera: Curculionidae) to different strains/species of entomopathogenic fungi and nematodes was evaluated in laboratory by soil cup bioassays. In the experiments with fungi, a wild strain of Metarhizium anisopliae caused the highest larval mortality (about 90%) compared with a commercial and a wild strain of Beauveria bassiana (80% and 77% respectively). Regarding nematodes, the commercial strain of Heterorhabditis bacteriophora was more effective in the control of chestnut larvae (77% insect mortality) than Steinernema carpocapsae (43%).