Volatile Organic Compounds from Entomopathogenic and Nematophagous Fungi, Repel Banana Black Weevil (Cosmopolites sordidus)

Fungal Volatile Organic Compounds (VOCs) repel banana black weevil (BW), Cosmopolites sordidus (Germar, 1824), the key-pest of banana [Musa sp. (Linnaeus, 1753)]. The entomopathogens Beauveria bassiana (Bb1TS11) and Metarhizium robertsii (Mr4TS04) were isolated from banana plantation soils using an insect bait. Bb1TS11 and Mr4TS04 were pathogenic to BW adults. Bb1TS11, Bb203 (from infected palm weevils), Mr4TS04 and the nematophagous fungus Pochonia clamydosporia (Pc123), were tested for VOCs production. VOCs were identified by Gas Chromatography/Mass Spectrometry–Solid-Phase Micro Extraction (GC/MS-SPME). GC/MS-SPME identified a total of 97 VOCs in all strains tested. Seven VOCs (styrene, benzothiazole, camphor, borneol, 1,3-dimethoxy-benzene, 1-octen-3-ol and 3-cyclohepten-1-one) were selected for their abundance or previous record as insect repellents. BW-starved adults in the dark showed the highest mobility to banana corm in olfactometry bioassays. 3-cyclohepten-1-one (C7), produced by all fungal strains, is the best BW repellent (p < 0.05), followed by 1,3-dimethoxy-benzene (C5). The rest of the VOCs have a milder repellency to BW. Styrene (C1) and benzothiazole (C2) (known to repel palm weevil) block the attraction of banana corm and BW pheromone to BW adults in bioassays. Therefore, VOCs from biocontrol fungi can be used in future studies for the biomanagement of BW in the field.This research was funded by H2020 European Project Microbial Uptakes for Sustainable management of major bananA pests and diseases with project number 727624

The Aleurocanthus spiniferus (OSW) in Europe: a becoming invasive threat to citrus also.

The orange spiny whitefly (OSW), Aleurocanthus spiniferus, is a worldwide known citrus pest native to tropical Asia. Since the beginning of the 20th century, OSW spread throughout Asia, the Pacific, central and Southern Africa and from 2008 it was intercepted many times in EPPO area (Italy, Croatia and Montenegro). OSW polyphagy is well known, being able to infest more than 90 host plants belonging to unrelated botanical families, although Citrus spp. are considered the primary hosts. Accurate samplings highlighted OSW new host associations extending the range of plant families potentially exploitable and confirming the existence of host-shift phenomena. Analyses of the mitochondrial COI gene revealed that OSW Apulian population belongs solely to one of the two haplogroups present in China. Furthermore, the study of microbiota allowed us to identify the principal endosymbiotic bacteria in OSW. So far, field samplings confirmed the presence of predators belonging to Coccinellidae family able to prey on different evelopmental stages of A. spiniferus. These findings could be considered as an opportunity for biological control of OSW. Results laid solid foundations in the knowledge of European OSW populations now invading Italy and neighbouring countries to counteract a pan-Mediterranean invasion of this harmful whitefly. Further studies are essential for the assessment of an effective IPM strategy tailored either for organic or intensive agricultural context

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

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

<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

Correction: Lozano-Soria et al. Volatile Organic Compounds from Entomopathogenic and Nematophagous Fungi, Repel Banana Black Weevil (Cosmopolites sordidus). Insects 2020, 11, 509

Fungal Volatile Organic Compounds (VOCs) repel banana black weevil (BW), Cosmopolites sordidus (Germar, 1824), the key-pest of banana [Musa sp. (Linnaeus, 1753)]. The entomopathogens Beauveria bassiana (Bb1TS11) and Metarhizium robertsii (Mr4TS04) were isolated from banana plantation soils using an insect bait. Bb1TS11 and Mr4TS04 were pathogenic to BW adults. Bb1TS11, Bb203 (from infected palm weevils), Mr4TS04 and the nematophagous fungus Pochonia clamydosporia (Pc123), were tested for VOCs production. VOCs were identified by Gas Chromatography/Mass Spectrometry–Solid-Phase Micro Extraction (GC/MS-SPME). GC/MS-SPME identified a total of 97 VOCs in all strains tested. Seven VOCs (styrene, benzothiazole, camphor, borneol, 1,3-dimethoxy-benzene, 1-octen-3-ol and 3-cyclohepten-1-one) were selected for their abundance or previous record as insect repellents. In olfactometry bioassays, BW- starved adults in the dark showed the highest mobility to banana corm. 2-cyclohepten-1-one (C7), commercially available isomer of 3-cyclohepten-1-one, is the best BW repellent (p &lt; 0.05), followed by 1,3-dimethoxy-benzene (C5). The rest of the VOCs have a milder repellency to BW. Styrene (C1) and benzothiazole (C2) (known to repel palm weevil) block the attraction of banana corm and BW pheromone to BW adults in bioassays. Therefore, VOCs from biocontrol fungi can be used in future studies to biomanage BW in the field

An Eretmocerus Species, Parasitoid of Aleurocanthus spiniferus, Was Found in Europe: The Secret Savior of Threatened Plants

This study focuses on the first detection in Europe of a parasitoid Eretmocerus sp. gr. serius (Hymenoptera: Aphelinidae) on the Orange Spiny Whitefly, Aleurocanthus spiniferus (Quaintance) (Hemiptera: Aleyrodidae). Through extensive field surveys, this study investigates the occurrence of the aphelinid in several regions across central and southern Italy. Different sites were monitored to investigate the Eretmocerus sp. gr. serius parasitization rate on A. spiniferus, shedding light on its potential as a biological control agent against the invasive whitefly pest. The research results offer a hopeful prospect for progressing sustainable and eco-friendly methods in handling A. spiniferus infestations in citrus crops, highlighting the importance of natural enemies in integrated pest man- agement programs. The research emphasizes the importance of the recently discovered parasitoid for European agriculture, paving the way for inventive approaches in pest control and cultivation practices

Brindley’s Glands Volatilome of the Predator <i>Zelus renardii</i> Interacting with <i>Xylella</i> Vectors

Alien species must adapt to new biogeographical regions to acclimatise and survive. We consider a species to have become invasive if it establishes negative interactions after acclimatisation. Xylella fastidiosa Wells, Raju et al., 1986 (XF) represents Italy’s and Europe’s most recent biological invasion. In Apulia (southern Italy), the XF-encountered Philaenus spumarius L. 1758 (Spittlebugs, Hemiptera: Auchenorrhyncha) can acquire and transmit the bacterium to Olea europaea L., 1753. The management of XF invasion involves various transmission control means, including inundative biological control using Zelus renardii (ZR) Kolenati, 1856 (Hemiptera: Reduviidae). ZR is an alien stenophagous predator of Xylella vectors, recently entered from the Nearctic and acclimated in Europe. Zelus spp. can secrete semiochemicals during interactions with conspecifics and prey, including volatile organic compounds (VOCs) that elicit conspecific defence behavioural responses. Our study describes ZR Brindley’s glands, present in males and females of ZR, which can produce semiochemicals, eliciting conspecific behavioural responses. We scrutinised ZR secretion alone or interacting with P. spumarius. The ZR volatilome includes 2-methyl-propanoic acid, 2-methyl-butanoic acid, and 3-methyl-1-butanol, which are consistent for Z. renardii alone. Olfactometric tests show that these three VOCs, individually tested, generate an avoidance (alarm) response in Z. renardii. 3-Methyl-1-butanol elicited the highest significant repellence, followed by 2-methyl-butanoic and 2-methyl-propanoic acids. The concentrations of the VOCs of ZR decrease during the interaction with P. spumarius. We discuss the potential effects of VOC secretions on the interaction of Z. renardii with P. spumarius