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Spittlebugs vs predators: the importance of incidental vibrations for the detection of threats by insect vectors of Xylella fastidiosa
No full textThe vibrational disruption of insect pests’ interaction with the environment is a new promising frontier in the control of either direct pest or insect vectors of plant pathogens. Reducing the frequency of insect–plant interactions leveraging on vibrational stimuli evoking the risk of predation could potentially affect the transmission rate of vector-borne plant pathogens as Xylella fastidiosa, whose main vector in Europe is the meadow spittlebug Philaenus spumarius. Here, we sought to address a fundamental question in the development of a behavioral manipulation strategy to disrupt spittlebug-mediated transmission of X. fastidiosa: are incidental vibrations emitted by predators a significant factor in spittlebugs’ risk detection? To respond to this question, we compared Philaenus spumarius response to hunting spiders collected in Apulian (southeastern Italy) olive orchards with the response to the sole spider vibrations recorded with a laser vibrometer and played back through a mini-shaker. A white noise and a leafhopper-emitted vibration were used as controls to evaluate spittlebugs’ response to vibrational signals not associated with a predation risk. In all trials, P. spumarius main response to spiders searching for the prey was freezing, i.e., cessation of any kind of activity. In playback trials, incidental vibrations alone emitted by spiders’ foraging triggered a freezing response in 63% of the tested spittlebugs; the duration of the freezing was approximately half of the duration of the behavior in response to the spider. Freezing was significantly more frequent in response to spider-foraging vibration (63%) than to the white noise and the leafhopper-emitted vibration (both 10%); no freezing was observed in the silent control. Overall, our findings suggest that substrate-borne vibrations are an important component of predation-risk assessment in P. spumarius. However, the perception and the response to a threat are likely multimodal processes mediated by the integration of vibrations with chemical and visual cues. Our results pave the way for the development of a behavioral disruption strategy against spittlebugs and X. fastidiosa transmission based on natural enemies-derived substrate-borne vibration
Hunting, but not outdoor recreation, modulates behavioural tolerance to human disturbance in Alpine marmots Marmota marmota
Full text linkHumans are often perceived as predators by free-living animals, and thus, even nonconsumptive human activities such as outdoor recreation may trigger behavioural and physiological responses, often with negative consequences on individual fitness and population persistence. Nonetheless, there is growing evidence that wildlife can also have remarkable behavioural tolerance, but no clear picture has yet emerged regarding the mechanisms explaining different responses to humans. We investigated the effect of different types of human activity – hunting and outdoor recreation – on behavioural tolerance to humans in Alpine marmots Marmota marmota. Marmots were studied in areas with contrasting protection regimes and under different levels of outdoor recreation in northern Italy over three seasons (2021–2023). Flight initiation distance (i.e. the distance at which an animal escapes from an approaching person) was used as a proxy of tolerance to human disturbance and tested against levels of outdoor recreation and hunting using linear mixed modelling. Marmots were more sensitive to human disturbance in hunted as compared to protected areas, whereas we did not find evidence for changes in behavioural tolerance when exposed to varying levels of outdoor recreation. In turn, our study suggests that hunting, by reducing behavioural tolerance to humans, could exacerbate the negative effects of non-lethal human activities on wildlife. This has implications for conservation and management strategies aimed at promoting coexistence in human-altered landscape
Genomic insights into the virulence repertoire and hemibiotrophic lifestyle of the grapevine black rot pathogen Phyllosticta ampelicida
Full text linkPhyllosticta ampelicida, the causal agent of grapevine black rot, is a globally emerging pathogen that infects all grapevine green tissues, with young shoots and berries being particularly susceptible. Severe infections can result in total crop loss. To investigate its virulence repertoire, we generated a high-quality genome assembly of strain GW18.1 using long-read sequencing, resulting in 22 scaffolds, including four complete chromosomes and 12 chromosome arms, with a total genome size of 35.6 Mb and 10,289 predicted protein-coding genes. Two additional strains (TN2 and LB22.1) were sequenced with short reads to assess intraspecies diversity. Comparative genomics revealed a conserved virulence factor repertoire, including 314 carbohydrate-active enzymes (CAZymes), 17 cytochrome P450s, 35 peroxidases, and 20 secondary metabolite biosynthetic gene clusters (BGCs). Trophic lifestyle prediction based on gene content supports a biotrophic-like lifestyle consistent with hemibiotrophic pathogens. Broader comparisons with other Phyllosticta species and ten plant-pathogenic fungi pointed to species-specific features, while analysis of gene family evolution identified expansions and contractions in transporters and CAZymes. These genomic resources will support efforts to better understand and manage grapevine black ro
Effect of saffron extract supplementation on mood in healthy adults with subclinical symptoms of depression: a randomized, double-blind placebo-controlled study
Full text linkBackground Subclinical depressive symptoms, including low mood, fatigue and anxiety, refer to clinically relevant depressive manifestations that do not meet the criteria for major depressive disorder. These symptoms affect quality of life and can lead to chronic mental health issues. Nutritional interventions, such as saffron extract supplementation, may help modulate mood and inflammation, potentially alleviating these symptoms. Objective This study aims to evaluate the efficacy of a 6-week saffron extract supplementation on mood in healthy individuals with subclinical neuropsychiatric symptoms and explored the underlying mechanisms. Methods This randomized, double-blind, placebo-controlled study involved 51 adult healthy individuals who received oral administration of either saffron extract or a placebo for 6 weeks. The primary outcome was a composite z-score averaging standardized scores of depression (BDI-II), anxiety (STAI-YA), and fatigue (MFI-20). Secondary outcomes included neuropsychiatric scores, quality of life, inflammatory markers and hypothalamic-pituitary-adrenal (HPA) axis reactivity. Amino acid derivatives were analysed in blood samples. Results Saffron extract did not significantly affect the primary outcome of combined depressive, anxiety, and fatigue symptoms (z-score) nor individual symptoms. However, it improved auto-perceived mental health, as reflected in increased mental health scores over time on the Medical Outcome Study Short Form 12 questionnaire, compared to placebo (mean at 6 weeks=53.8 ± 12.7 vs 44.6 ± 11.4 for placebo and saffron group respectively, Time x Treatment=0.04). There were no significant effects on inflammatory parameters or HPA axis reactivity. Metabolomic analysis revealed that saffron extract significantly modulated N-acetyl-phenylalanine. Conclusion Saffron extract supplementation did not affect subclinical depressive symptoms, either measured as a composite score or individual symptom categories. A potential effect on improved mental health outcomes cannot be excluded but requires further replication in future well-powered trials. Saffromfood study, clinicaltrial.gov: NCT05690126. https://clinicaltrials.gov/study/NCT05690126?term=NCT05690126&rank=