Biology subjects

Ment, D.

Publications and source records attributed to Ment, D..

5 recordsLinked to original sources

bioRxiv2025

Entomopathogenic fungi as dual-function biocontrol agents: persistence and microbiome modulation in date palm soils

The effects of entomopathogenic fungi (EPF) on native soil microbiota are poorly understood. Here, we investigated the persistence of the EPF Metarhizium brunneum and Beauveria bassiana as preventive treatments for date palms against the red palm weevil, Rhynchophorus ferrugineus, and monitored the microbial community within the palms. We assessed the changes in the soil microbiota of the palms following application by fungal soil isolation techniques, high-throughput metagenomics, EPF persistence assays, and accompanied that with a continuous monitoring of date palm health. EPF preemptive treatments significantly improved palm protection against the weevil. While both EPF species persisted for 180 days post-application, their effectiveness diverged, with B. bassiana providing longer palm protection. Overall microbial community composition showed no major changes following EPF applications; however, transient alterations increased the relative abundance of local EPF genera, with dominant taxa being more likely to persist. Both EPF treatments enhanced the relative abundance of nitrogen-fixing bacteria, organic matter decomposers, and ammonia-oxidizing archaea, suggesting potential implications for nutrient cycling that require further validation through direct functional measurements. B. bassiana induced the strongest temporal effects on diversity indices, while M. brunneum was more persistent but showed no significant changes in diversity indices compared to the control. These results highlight EPF as a multifunctional biocontrol agent - moderately shaping soil microbiomes for beneficial ecosystem functions.

microbiology↗

bioRxiv2025

Deciphering the Survival Strategies of the Entomopathogenic Nematode Steinernema carpocapsae Using Rapid Desiccation Assisted by Nanoparticle-Based Emulsion

Water retention is essential for survival under desiccating conditions, especially for entomopathogenic nematodes (EPNs) used as biocontrol agents. Foliar application of EPNs causes rapid desiccation (RD), severely reducing their survival and efficacy. We investigated the physiological and molecular responses of Steinernema carpocapsae to RD, delivered in a novel nanoparticle-stabilized emulsion to improve tolerance under variable humidity. We hypothesized that the formulation would enhance EPNs survival, by promoting early stress-responsive pathways and water-retention mechanisms. Formulated nematodes exhibited delayed water loss and increased survival under low humidity compared with non-formulated controls. The emulsion mitigated RD by enhanced hydration retention and reduced water loss, effects that were strongly associated with differential trehalose accumulation. In addition, maintenance of basement membrane integrity and cytoskeletal organization, emerged as a critical component of desiccation. These findings advance understanding of RD tolerance in EPNs and demonstrate how tailored formulation strategies can protect biocontrol agents under desiccation stress.

developmental biology↗

bioRxiv2024

Female Moths Incorporate Plant Acoustic Emissions into Their Oviposition Decision

Insects rely on plants visual, chemical, tactile, and electrical cues when making various decisions. A recent study demonstrated that dehydrated plants emit ultrasonic sounds within the auditory sensitivity range of many moth species. In this study, we sought to determine whether insects also rely on plant acoustic signals when making decisions. We investigated whether female moths rely on ultrasonic clicks which are typically produced by dehydrated plants when deciding where to oviposit. In the absence of an actual plant, the moths indeed preferred to lay their eggs in proximity to acoustic signals which represent dehydrating plants. Tracking the moths behavior prior to the decision showed that they examined both sides of the arena and gradually spent more time on the acoustic-playback side. Interestingly, when actual plants were added to the arena, the oviposition preference was reversed and the moths preferred silent plants, which is in accordance with their a-priori preference for hydrated plants. Deafening the moths eliminated their preference, confirming that the choice was based on hearing. Moreover, the presence of male moths including their auditory signals did not affect their oviposition decision, suggesting that the response was specific to plant sound emissions. We reveal evidence for a first acoustic interaction between moths and plants, but as plants emit various sounds, our findings hint to the existence of more currently unknown insect-plant acoustic interactions.

animal behavior and cognition↗

bioRxiv2024

The efficacy of the Entomopathogenic Fungus, Beauveria bassiana, in Date Palm Protection against the Red Palm Weevil, Rhynchophorus Ferrugineus, Under Hot Dessert Climate

The red palm weevil (Rhynchophorus ferrugineus; RPW) is an important pest threatening date palm cultivation worldwide. Conventional insecticide-based management is limited by environmental concerns and the development of resistance in RPW populations. Entomopathogenic fungi (EPF), such as Beauveria bassiana, offer a promising biocontrol alternative. While laboratory and semifield studies have demonstrated their potential as insecticides, evidence from field-scale applications under diverse environmental conditions remains scarce. This study evaluated the seasonal efficacy and persistence of B. bassiana as a preventive treatment against RPW in male and female date palm groves subjected to different cultivation practices in Israels Arava region. Healthy palms were equipped with IoTree sensors to monitor RPW infestation dynamics. EPF treatments were applied at the start of each season, and control trees were left untreated. Soil samples were collected seasonally to quantify fungal colony-forming units (CFUs) and assess their association with treatment outcomes. Results demonstrated a significant seasonal influence on EPF efficacy, with autumn treatments yielding the highest reduction in infestation rates, and summer applications showing limited effectiveness. Efficacy also varied between grove types: spring applications were most effective in male groves, whereas autumn treatments were superior in female groves. A positive correlation was found between B. bassiana CFUs in the soil and palm health, indicating that EPF persistence enhances treatment success. These findings highlight the importance of seasonal and site-specific optimization of EPF-based biocontrol strategies. Further research is needed to refine application schedules and validate outcomes across larger-scale trials.

ecology↗

bioRxiv2023

Type VII secretion system and its effect on Group B Streptococcus virulence

GBS may cause a devasting disease in newborns. In early onset disease of the newborn the bacteria are acquired from the colonized mother during delivery. We characterized type VII secretion system (T7SS), exporting small proteins of the WXG100 superfamily, in group B Streptococci (GBS) isolates from pregnant colonized women and newborns with early onset disease (EOD) to understand better understand T7SS contribution to virulence in these different clinical scenarios. GBS isolates were obtained from colonized mother prior to delivery and from newborns with EOD. DNA was analyzed for T7SS genes. A mutant EOD strain (ST17) was created by knocking out the essC gene encoding a T7SS protein. Galleria mellonella larvae were used to compare virulence of colonizing, EOD, and mutant EOD isolates. 33 GBS genomes were tested, 17 EOD isolates and 16 colonizing isolates. The T7SS locus encoded 8 genes: essC, membrane-embedded proteins (essA; essB), modulators of T7SS activity (esaA; esaB; esaC) and effectors: [esxA (SAG1039); esxB (SAG1030). ST17 isolates encode two copies of the essC gene and esxA gene encoding putative effectors but were present only in 23.5% of isolates. In ST1 isolates three copies of esxA gene were identified, but in ST6 and ST19 isolates all T7SS genes were missing. EOD isolates demonstrated enhanced virulence in G. mellonella model compared to colonizing isolates. The 118659{Delta}essC strain was attenuated in its killing ability, and the larvae were more effective in eradicating 118659{Delta}essC infection. essC gene deletion was associated with reduced bacterial growth. We demonstrated that T7SS plays an essential role during infection and contributes to GBS pathogenicity. Author SummaryType VII secretion system (T7SS) is related to virulence in various bacteria but is not well characterized in Group B Streptococci (GBS). GBS may cause sepsis, meningitis, and death in newborns. The bacteria rarely cause disease in pregnant mothers. Newborns acquire GBS from the colonized mother during delivery. We studied the role of T7SS in GBS isolates obtained from newborns with GBS sepsis in the first week of life and in colonized pregnant mothers. By studying T7SS genes we discovered that the genetic structure of the T7SS differs between isolates causing severe disease and colonizing isolates. To study the virulence of different GBS isolates we injected them into larvae and monitored larvae survival. Isolates causing severe disease in the newborn caused a more severe disease in larvae compared to colonizing isolates. We then deleted T7SS genes in GBS isolates causing severe disease. The killing activity of GBS isolates without T7SS genes was attenuated. The larva responded to these bacteria similarly to the response found when injecting the larva with GBS isolates from colonized mothers. These results support our hypothesis that T7SS is important for causing severe infection in the newborn and that this system contributes to GBS pathogenicity.

microbiology↗