Aleurocanthus spiniferus, an alien invasive threat to Europe. AssociatEd bacterial community and natural enemies

Aleurocanthus spiniferus also known as orange spiny whitefly (OSW), is a pest native to tropical Asia that in the last century has spread throughout Asia, reaching Africa, Australia, and Pacific islands. In 2008 the first European OSW population was recorded in Apulia region (South East Italy) and allowed EPPO to add the species as a quarantine threat to Europe now in the A2 list. In the following years OSW spread and invaded new territories of Italy, Croatia and Montenegro. Although OSW polyphagy is already well-known, new associations with autochthonous and allochthonous plants have been reported showing its host-shifting ability. To counteract an upcoming pan-Mediterranean invasion updated bio-ethological information of the pest and the role of possible natural enemies are essential to implement a correct IPM strategy. Field samplings have been aimed at the identification of natural enemies and the evaluation of their efficacy. Furthermore, through insect small-RNA sequencing and by Denaturing Gradient Gel Electrophoresis (DGGE) technique coupled with 16S-rRNA gene sequencing, the primary symbiotic bacteria of OSW have been identified. Sampling on natural enemies highlighted the presence of predatory species belonging to the Coccinellidae family. Besides to the almost ineffective populations of Oenopia conglobata and Clithostetus arcuatus, new findings detected scattered Delphastus sp. populations along the western coast of Italy. Both adult and larvae of this ladybird species preyed OSW developmental stages. The evaluation of the role of Delphastus sp. as biocontrol agent is underway. The first study on OSW microbiota allowed to find symbiotic bacteria commonly associated with the genus Aleurocanthus: Portiera sp., Serratia sp., Wolbachia sp., Rickettsia sp. and, although sporadically, other species. Further studies will target the functional role of these symbionts to develop an effective IPM tailored for Countries at risk

Postharvest Diseases of Pomegranate: Alternative Control Means and a Spiderweb Effect

The pomegranate is a fruit known since ancient times for its beneficial properties. It has recently aroused great interest in the industry and among consumers, leading to a significant increase in demand. Consequently, its cultivation has been boosted all over the world. The pomegranate crop suffers considerable yield losses, especially at the postharvest stage, because it is a “minor crop” with few permitted control means. To control latent (Alternaria spp., Botrytis spp., Coniella spp., Colletotrichum spp., and Cytospora spp.) and wound (Aspergillus spp., Penicillium spp., and Talaromyces spp.) fungal pathogens, different alternative compounds, previously evaluated in vitro, were tested in the field on pomegranate cv. Wonderful. A chitosan solution, a plant protein hydrolysate, and a red seaweed extract were compared with a chemical control treatment, all as preharvest (field application) and postharvest treatments and their combinations. At the end of the storage period, the incidence of stamen infections and external and internal rots, and the severity of internal decay were evaluated. Obtained data revealed that pre- and postharvest application of all substances reduced the epiphytic population on stamens. Preharvest applications of seaweed extract and plant hydrolysate were the most effective treatments to reduce the severity of internal pomegranate decays. Furthermore, the influence of spider (Cheiracanthium mildei) cocoons on the fruit calyx as a possible barrier against postharvest fungal pathogens was assessed in a ‘Mollar de Elche’ pomegranate organic orchard. Compared to no-cocoon fruit (control), the incidence of infected stamens and internal molds in those with spiderwebs was reduced by about 30%, and the mean severity of internal rots was halved. Spiderwebs analyzed via Scanning Electron Microscopy (SEM) disclosed a layered, unordered structure that did not allow for the passage of fungal spores due to its mean mesh size (1 to 20 µm ca). The aims of this research were (I) to evaluate alternative compounds useful to control postharvest pomegranate decays and (II) to evaluate the effectiveness of spiders in reducing postharvest fungal infections by analyzing related mechanisms of action. Alternative control means proposed in the present work and calyx spider colonization may be helpful to reduce postharvest pomegranate diseases, yield losses, and waste production in an integrated control strategy, satisfying organic agriculture and the planned goals of Zero Hunger Challenge launched by the United Nations

“Ectomosphere”: Insects and Microorganism Interactions

This study focuses on interacting with insects and their ectosymbiont (lato sensu) microorganisms for environmentally safe plant production and protection. Some cases help compare insect-bearing, -driving, or -spreading relevant ectosymbiont microorganisms to endosymbionts’ behaviour. Ectosymbiotic bacteria can interact with insects by allowing them to improve the value of their pabula. In addition, some bacteria are essential for creating ecological niches that can host the development of pests. Insect-borne plant pathogens include bacteria, viruses, and fungi. These pathogens interact with their vectors to enhance reciprocal fitness. Knowing vector-phoront interaction could considerably increase chances for outbreak management, notably when sustained by quarantine vector ectosymbiont pathogens, such as the actual Xylella fastidiosa Mediterranean invasion episode. Insect pathogenic viruses have a close evolutionary relationship with their hosts, also being highly specific and obligate parasites. Sixteen virus families have been reported to infect insects and may be involved in the biological control of specific pests, including some economic weevils. Insects and fungi are among the most widespread organisms in nature and interact with each other, establishing symbiotic relationships ranging from mutualism to antagonism. The associations can influence the extent to which interacting organisms can exert their effects on plants and the proper management practices. Sustainable pest management also relies on entomopathogenic fungi; research on these species starts from their isolation from insect carcasses, followed by identification using conventional light or electron microscopy techniques. Thanks to the development of omics sciences, it is possible to identify entomopathogenic fungi with evolutionary histories that are less-shared with the target insect and can be proposed as pest antagonists. Many interesting omics can help detect the presence of entomopathogens in different natural matrices, such as soil or plants. The same techniques will help localize ectosymbionts, localization of recesses, or specialized morphological adaptation, greatly supporting the robust interpretation of the symbiont role. The manipulation and modulation of ectosymbionts could be a more promising way to counteract pests and borne pathogens, mitigating the impact of formulates and reducing food insecurity due to the lesser impact of direct damage and diseases. The promise has a preventive intent for more manageable and broader implications for pests, comparing what we can obtain using simpler, less-specific techniques and a less comprehensive approach to Integrated Pest Management (IPM).The present work acknowledges the support from: European Union’s Horizon 2020 research and innovation programme under Grant Agreements No. 635646-POnTE “Pest Organisms Threatening Europe”, No. 727987-XF-ACTORS “Xylella Fastidiosa Active Containment Through a multidisciplinary-Oriented Research Strategy”, Grant number 952337-MycoTWIN “Enhancing Research and Innovation Capacity of Tubitak MAM Food Institute on Management of Mycotoxigenic Fungi and Mycotoxins”, and CURE-Xf, H2020-Marie Sklodowska-Curie Actions—Research and Innovation Staff Exchange. Reference number: 634353, coordinated by CIHEAM Bari. The EU Funding Agency is not responsible for any use that may be made of the information it contains. European Union’s StopMedWaste “Innovative Sustainable technologies TO extend the shelf-life of Perishable MEDiterranean fresh fruit, vegetables and aromatic plants and to reduce WASTE” a PRIMA project ID: 1556. European Union’s Euphresco BasicS “Basic substances as an environmentally friendly alternative to synthetic pesticides for plant protection” project ID: 2020-C-353. The work was partially carried out in the framework of the National Projects: RIGENERA, granted by MASAF n. 207631, 9 May 2022, and GENFORAGRIS, granted by MASAF n. 207631, 9 May 2022; and regional projects “Laboratory network for the selection, characterisation and conservation of germplasm and for preventing the spread of economically-relevant and quarantine pests (SELGE) No. 14”, founded by the Apulia Region, PO FESR 2007–2013—Axis I, Line of intervention 1.2., Action 1.2.1; Research for Innovation (REFIN) POR Puglia 2014–2020 Project: 8C6E699D, and PON AIM, COD. AIM 1809249-Attività 1 Linea 1

First report of Curvularia spicifera causing brown rot of citrus in Southern Italy

In 2014, rot symptoms were observed on mandarin fruits (Citrus reticulata) in a grove of Metaponto (southern Italy). Five to 7 mm lesions, colonized by a brown mycelium characterized diseased tissues. Fruit was collected, and surface-sterilized in 2% sodium hypochlorite. Tissue portions, removed in between symptomatic and healthy areas, were placed on potato dextrose agar (PDA) selective for yeasts and fungi and incubated at 24°C. The obtained fungal isolate was deposited in the collection of DISSPA, University of Bari, Italy, in its monoconidial form. On PDA, colonies were fast growing, initially light brown, turning dark brown after 7 days, raised and lobate-undulate. The aerial mycelium was cottony. Conidia were 18.5 ± 3 μm long × 7 ± 3.4 μm wide, ellipsoidal or oblong, straight, with rounded ends, light brown, 3-transverse septated, with an evident hilum and walls fairly thick, thinner towards the ends. Conidiophore light to medium brown, of variable length, scattered or clustered, often branching were observed. Based on these morphological characters, the fungus was identified as Curvularia spicifera (Bainier) Boedijn

A biological control model to manage the vector and the infection of Xylella fastidiosa on olive trees

Xylella fastidiosa pauca ST53 is the bacterium responsible for the Olive Quick Decline Syn- drome that has killed millions of olive trees in Southern Italy. A recent work demonstrates that a rational integration of vector and transmission control measures, into a strategy based on chemical and physical control means, can manage Xylella fastidiosa invasion and impact below an acceptable economic threshold. In the present study, we propose a biological alternative to the chemical control action, which involves the predetermined use of an avail- able natural enemy of Philaenus spumarius, i.e., Zelus renardii, for adult vector population and infection biocontrol. The paper combines two different approaches: a laboratory experi- ment to test the predation dynamics of Zelus renardii on Philaenus spumarius and its atti- tude as candidate for an inundation strategy; a simulated experiment of inundation, to preliminary test the efficacy of such strategy, before eventually proceeding to an in-field experimentation. With this double-fold approach we show that an inundation strategy with Zelus renardii has the potential to furnish an efficient and “green” solution to Xylella fasti- diosa invasion, with a reduction of the pathogen incidence below 10%. The biocontrol model presented here could be promising for containing the impact and spread of Xylella fasti- diosa, after an in-field validation of the inundation technique. Saving the fruit orchard, the production and the industry in susceptible areas could thus become an attainable goal, within comfortable parameters for sustainability, environmental safety, and effective plant health protection in organic orchard management

Morphs of Philaenus species, candidate Xylella fastidiosa vectors

The genus Philaenus presents a well-known colour polymorphism, allowing discrimination of morphs and engaging non-skilled practitioners in species identification. This study considers a collection of approximately 2500 Philaenus spp. individuals from southern Italy and northern Tunisia. We felt a morph valid if in our collection or recorded in a minimum of two different references from different geographical locations or timepoints. Reviewing the literature for phenotypes allowed the development of a key to discriminate between the 25 available phenotypes. The study suggests that Philaenus spumarius has twenty-three morphs, followed by the eight morphs of Philaenus signatus, the seven of Philaenus tesselatus, the six of Philaenus italosignus, Philaenus maghresignus, and Philaenus tarifa, the two of Philaenus loukasi, and one of Philaenus arslani. P. maghresignus and P. tesselatus show all morphs cited in the literature plus a gibba morph based on single female individuals. P. spumarius was absent from Tunisian collections; therefore, all data on P. spumarius rely on Italian specimens. De-greasing revealed the true phenology of individuals, allowing the classification of ambiguous individuals. Light microscope and SEM observations in P. spumarius recently collected in southern Italy (Apulia region) revealed six concave hairless spots on the pronotum corresponding to the dark spots of impressa morph, a morph hitherto only known from North America only. Xylella fastidiosa was isolated and described in Nearctic. The recent finding of impressa morph in Italy may suggest a different route of bacterium introduction in the Old Word by adult vector importation

First Report of Aleurocanthus spiniferus on Ailanthus altissima: Profiling of the Insect Microbiome and MicroRNAs

We report the first occurrence of the orange spiny whitefly (Aleurocanthus spiniferus; OSW) on the tree of heaven (Ailanthus altissima) in Bari, Apulia region, Italy. After our first observation in 2016, the infestation recurred regularly during the following years and expanded to the neighboring trees. Since then, we have also found the insect on numerous patches of the tree of heaven and other plant species in the Bari province. Nevertheless, the tree of heaven was not particularly threatened by the insect, so that a possible contribution by OSW for the control of such an invasive plant cannot be hypothesized hitherto. This work was also aimed at profiling the microbiome of OSW feeding on A. altissima. For this purpose, we used the denaturing gradient gel electrophoresis (DGGE) and the deep sequencing of small RNAs (sRNAs). Both techniques unveiled the presence of “Candidatus Portiera” (primary endosymbiont), Wolbachia sp. and Rickettsia sp., endosymbionts already reported for other Aleyrodidae. Deep sequencing data were analyzed by four computational pipelines in order to understand the reliability of the detection of fungi, bacteria, and viruses: Kraken, Kaiju, Velvet, and VelvetOptimiser. Some contigs assembled by Velvet or VelvetOptimiser were associated with insects, but not necessarily in the Aleurocanthus genus or Aleyrodidae family, suggesting the non-specificity of sRNAs or possible traces of parasitoids in the sample (e.g., Eretmocerus sp.). Finally, deep sequencing data were used to describe the microtranscriptome of OSW: 56 canonical and at least four high-confidence novel microRNAs (miRNAs) were identified. The overall miRNA abundance in OSW was in agreement with previous works on Bemisia tabaci, and bantam-3p, miR-276a-3p, miR-317-3p, miR-750-3p, and mir-8-3p were the most represented miRNAs

<i>Zelus renardii</i> Roaming in Southern Italy

This study collects data from the literature and updates our Zelus renardii Kolenati, 1856 (Leafhopper Assassin Bug, LAB) prey knowledge. The literature consists of ca. 170 entries encompassing the years 1856 to 2021. This reduviid originated in the Nearctic region, but has entered and acclimatised in many Mediterranean countries. Our quantitative predation experiments—in the laboratory on caged plants plus field or environmental observations—confirm that LAB prefers a selected array of prey. Laboratory predation tests on living targets (Hemiptera, Coleoptera, Diptera, and Hymenoptera) agree with the literature. Zelus renardii prefers comparatively large, highly mobile, and readily available prey. LAB preferences on available hemipterans targets suggest that Zelus renardii is a good inundative biocontrol agent for Xylella fastidiosapauca ST53 infections. LAB also prey on other important olive pests, such as Bactrocera oleae. Therefore, Zelus renardii is a major integrated pest management (IPM) component to limit Xylella fastidiosa pandemics and other pest invasions

Contamination of fresh and dried tomato by Alternaria toxins in southern Italy

In the present investigation, fresh and dried tomato samples from markets and packinghouses located in Apulia region (southern Italy) were analysed for Alternaria toxins. All samples proved to be contaminated by tenuazonic acid (TeA); in particular, dried tomatoes were contaminated in the range 425–81,592 μg/kg, while fresh tomatoes were in the range 11–4560 μg/kg. The second most abundant toxin was alternariol monomethyl ether (AME), followed by tentoxin (TEN) and alternariol (AOH). Overall dried tomatoes were more contaminated than fresh ones, although this seemed not directly related to the presence of sodium chloride, utilized in the drying process. Five representative Alternaria isolates within those collected from samples proved to be one Alternaria arborescens (A215) and four Alternaria alternata. Within the latter species, one strain belonged to morphotype tenuissima A216), and three to alternata (A214, A217 and A218). They were confirmed to produce TeA, AOH, and AME in vitro. This study demonstrates the possible risk for consumers’ health related to the consumption of contaminated fresh and dried tomatoes, and thus the need for suitable control strategies

EFFICACY OF A NEW SO2 GENERATOR PAD IN MAINTAINING POSTHARVEST QUALITY OF TABLE GRAPES

Gray mold is the most damaging postharvest disease of table grapes, due to the ability of the causal agent, Botrytis cinerea Pers., to adapt to different environmental conditions. A success factor in long-term storage of table grapes is the application of SO2 generator pads. Our research aimed at testing the activity of a new SO2 generator pad (Decco, Italia) on gray mold and quality of table grapes cv. Italia and Red Globe stored for 90 days. The test involved the application of the pad in three different moments: in the field, prior to precooling, and immediately after precooling. In addition, three different bags were used for packaging: perforated and unperforated plastic liners and the new Decco MAP (modified atmosphere packaging) bag. At 30 days of storage, ‘Red Globe’ packed in the field or just before precooling with SO2 generator, showed no infection by B. cinerea; while 23-33% of clusters were infected when the pad was inserted after precooling, with no significant differences among the various plastic liners used. Clusters cv. Italia showed a similar trend but a lower disease incidence as compared to ‘Red Globe’, with a maximum of 10% of infection in presence of SO2. The highest incidence of rots was recorded at 90 days on cv. Red Globe with increasing values moving from perforated to unperforated plastic liners and the new Decco MAP bag. In absence of SO2 generators, the infections on both cultivars reached 100%. Clusters of ‘Italia’ and ‘Red Globe’ packed with Decco MAP showed the best quality