Search

Scaphoideus titanus Ball (Hemiptera: Cicadellidae) is a major pest for European viticulture due to its high efficiency in the transmission of one of the most destructive pathogens for grapevine, namely flavescence dorée phytoplasmas. Although it plays a major role in spreading this disease, S. titanus is part of a complex epidemiological cycle involving several alternative vectors with variable relevance for phytoplasma spread. Here we provide an updated review on S. titanus monitoring and modelling, as well as the available tools for management of this pest and for limiting phytoplasma transmission and, thus, also spread. Insecticide-based control is examined; additional emphasis is placed on innovative and low-impact control approaches, such as vibrational mating disruption, biocontrol, and methods to reduce vector competence. We also discuss the main emerging challenges to the implementation of effective and sustainable control programs against S. titanus.

Native to the Nearctic region, Scaphoideus titanus Ball (Hemiptera: Cicadellidae) has become a major threat for grapevine production after being unintentionally introduced into Europe, where it became the main vector of flavescence dorée phytoplasma, being mainly associated with the genus Vitis. Scaphoideus titanus is a highly efficient vector of the most important phytoplasma affecting grapevine. For this reason, compulsory insecticide treatments have been introduced against this pest in many European countries. Moreover, the continuous expansion of its geographical distribution makes this leafhopper a serious threat for several non-European Countries. In this article, we review the current knowledge about its taxonomy, morphology, biology, ecology, and its role as a vector. Finally, we point out the main challenges for research aimed at reducing S. titanus and flavescence dorée expansion across Europe and avoiding spread of the disease outside the Old World.

Pentatomid insects harbour an obligate gut symbiont, vertically transmitted via egg smearing by the females. The disruption of symbiont acquisition can be exploited for pest management, by spraying the egg surface with anti-symbiont agents, yet the insect response to symbiont deprivation remains a determining aspect of the success of this strategy. Here the effect of anti-symbiont egg masses treatment was assessed in an Italian population of the southern green stink bug Nezara viridula under field and laboratory conditions. In soybean fields, N. viridula was poorly affected by treatment, whereas in laboratory, nymphs deriving from treated egg masses underwent increased mortality and symbiont abundance decline. The primary symbiont dominated the microbiome of non-treated nymphs showing low mortality. Conversely, dysbiosis was recorded in treated samples as well as in control nymphs with high mortality. Nonetheless, dysbiosis induced by treatment was not in all cases associated with high mortality, and symbiont was missing in some non-treated samples as well. Five variants of a Pantoea symbiont were found, with higher variant diversity in untreated samples with low mortality. Altogether, our results provide information about the gut microbiota dynamics in the early nymphal instars of N. viridula and suggest a still incomplete dependence on the symbiont. However, egg masses anti-symbiont treatment increased mortality, therefore symbiont-targeted control may be used against N. viridula as a supplementary tool under high pest pressure.

Background: In this study, a probiotic mixture (Honeybeeotic) consisting of seven bacterial strains isolated from a unique population of honeybees (Apis mellifera ligustica) was used. That honeybee population was located in the Roti Abbey locality of the Marche Region in Italy, an area isolated from human activities, and genetic contamination from other honeybee populations. The aim was to investigate the effects of this probiotic mixture on the innate immunity and intestinal microbiome of healthy common honeybees in two hives of the same apiary. Hive A received a diet of 50% glucose syrup, while hive B received the same syrup supplemented with the probiotics, both administered daily for 1 month. To determine whether the probiotic altered the immune response, phenoloxidase activity and hemolymph cellular subtype count were investigated. Additionally, metagenomic approaches were used to analyze the effects on gut microbiota composition and function, considering the critical role the gut microbiota plays in modulating host physiology. Results: The results revealed differences in hemocyte populations between the two hives, as hive A exhibited higher counts of oenocytoids and granulocytes. These findings indicated that the dietary supplementation with the probiotic mixture was safe and well-tolerated. Furthermore, phenoloxidase activity significantly decreased in hive B (1.75 ± 0.19 U/mg) compared to hive A (3.62 ± 0.44 U/mg, p< 0.005), suggesting an improved state of well-being in the honeybees, as they did not require activation of immune defense mechanisms. Regarding the microbiome composition, the probiotic modulated the gut microbiota in hive B compared to the control, retaining core microbiota components while causing both positive and negative variations. Notably, several genes, particularly KEGG genes involved in amino acid metabolism, carbohydrate metabolism, and branched-chain amino acid (BCAA) transport, were more abundant in the probiotic-fed group, suggesting an effective nutritional supplement for the host. Conclusions: This study advocated that feeding with this probiotic mixture induces beneficial immunological effects and promoted a balanced gut microbiota with enhanced metabolic activities related to digestion. The use of highly selected probiotics was shown to contribute to the overall well-being of the honeybees, improving their immune response and gut health.

Microbial biocontrol agents are promising tools for sustainable crop protection, as many strains showed high potential against various pathogens and pests. A still underexplored field for their use is symbiotic control, i.e. insect pest suppression through targeting obligate bacterial symbionts. Symbiotic control has been proposed against the brown marmorated stink bug Halyomorpha halys, by interrupting acquisition of its symbiont ‘Candidatus Pantoea carbekii’ by newborns from egg surface. We investigated the success of symbiotic control of H. halys by exposing various developmental stages to spray applications of the commercial formulation Amylo-X®, containing the biocontrol agent Bacillus velezensis (previously B. amyloliquefaciens). Along with treating egg masses, 2nd and 4th instar nymphs were submitted also to direct or residual contact exposures to explore the contribution of symbiont- and insect-targeted antagonistic action in short term. We demonstrated significant mortality induced in Amylo-X®-treated samples, regardless of the insect stage and type of contact. Quantitative PCR analysis indicated that death of neonates was related to the missed acquisition of P. carbekii, due to symbiont elimination from the egg surface. Nevertheless, nymphal mortality after direct contact with Amylo-X® seemed resulting from an unknown antagonistic activity exerted by B. velezensis. Residual contact induced a combination of anti-symbiont and anti-insect activities, depending on the exposed instar. Our results support the use of Amylo-X® for symbiotic control of H. halys through field applications targeting egg masses; still B. velezensis deserves further studies to explore its additional functions against insects.

The brown marmorated stink bug Halyomorpha halys is an invasive Asiatic pentatomid recently introduced in Europe. It is regarded as a major pest of many crops due to its marked polyphagy, high reproduction potential and high mobility. Among European countries where H. halys established in the last years, most of economic losses have been reported in Italy. A promising control approach against H. halys is based on the suppression of its gut primary symbiont ‘Candidatus Pantoea carbekii’ (P. carbekii), vertically transmitted through maternal secretions containing symbiotic bacteria smeared during oviposition, which are ingested by neonates. Symbiont elimination is regarded as a promising pest control strategy based on the application of antimicrobial substances. Here, an anti-symbiont activity is shown in response to the application of micronutrient fertilizers showing antimicrobial activity, resulting in H. halys nymphal mortality under laboratory conditions. Exposure to four commercial products, available for organic farming, was tested in combination with a pesticide additive on isolated stink bug egg masses, by measuring survival to II nymphal instar of neonates emerging from treated eggs. Zinc, copper and citric acid biocomplexes showed the most effective impact on H. halys survival, causing more than 90% nymph mortality. Molecular diagnosis for P. carbekii confirmed that observed effects were attributable to missed symbiont acquisition. Taken together, our results provide indication for the potential field use of micronutrient fertilizers as controls tool against H. halys. Future work will provide indications to maximize the effect of this approach in the field, enabling to design a new, eco-friendly approach for the control of this pest threatening Italian and European agriculture.