Biology subjects

Zytynska, S. E.

Publications and source records attributed to Zytynska, S. E..

10 recordsLinked to original sources

bioRxiv2026

Top-down and bottom-up landscape processes influence the formation of microbial partnerships in herbivorous insects

Many insects form intimate associations with microbial partners, spanning a continuum from obligate mutualisms to transient associations. These microbial partners confer a range of functional benefits, including protection from natural enemies, detoxification of plant secondary metabolites, and improved fitness. The prevalence and abundance of microbial symbionts can vary between insect populations, indicating that the insect-microbe relationship is influenced by external factors. However, little is known on the factors that determine the assembly, structure, and composition of the microbiome of herbivorous insects. We posit that the factors influencing the insect-microbe relationship occur at the landscape-scale, acting through a combination of bottom-up, top-down, and indirect effects between plants, herbivores, and their natural enemies. We test this in two agro-ecosystems by sampling individual insects from three sap-feeding and one leaf-chewing species. Our results explicitly show for the first time that habitat configurational complexity and the proportion of host-plant crop in the landscape, combined with natural enemy abundance, can act as direct and indirect drivers of microbial symbiosis in herbivorous insects. This highlights the wider implications landscape habitat and ecosystem structure has on species interactions across managed agricultural landscapes.

ecology↗

bioRxiv2026

Fungicide and warming interact to reduce soil ecosystem functioning

Soil microbial communities are essential to the functioning of their ecosystems, providing vital services such as plant growth promotion and bioremediation. However, intensively managed environments such as agricultural soils are increasingly challenged with multiple harsh environmental stressors from the compounding effects of climate change and conventional agricultural practices. Understanding how soil communities will respond to environmental stress along multiple axes is key for predicting how environmental change will impact terrestrial soil ecosystems. We combine experimental evolution with community phenotyping, 16s rRNA metabarcoding, fungicide resistance assays and plant experiments, to show that fungicide and warming temperatures together drive a synergistic reduction in soil community respiration rates, metabolic capacity and plant growth promotion (Hordeum vulgare), which would have been missed by looking at stressor effects independently. Dual stressors caused widespread loss of metabolic activity, particularly for carbohydrates and carboxylic acids, highlighting impairment of community function. Fungicide-evolved soil isolates had a 16-fold increase in fungicide resistance, but only in the absence of warming - suggesting that the dual stressor treatment constrained fungicide adaptation. Together, our findings suggest that the number of stressors (rather than the nuances of individual stressors) may be key for predicting soil microbial community responses to environmental change across multiple axes.

ecology↗

bioRxiv2024

Rhizobacteria prime the activation of defence and nutritional responses to suppress aphid populations on barley

O_LIInteractions between plant and soil microbes are widespread and modulate plant-insect herbivore interactions. Still, it remains unclear how these shapes the overall plant defence responses and the mechanisms involved. C_LIO_LIHere, we performed bioassays with barley (Hordeum vulgare) plants to study the underlying molecular pathways induced by two rhizobacteria, Acidovorax radicis or Bacillus subtilis, against the phloem feeding aphid Sitobion avenae over three timepoints. C_LIO_LIRoot colonization by A. radicis or B. subtilis suppressed aphid populations on barley. Analysis of differentially expressed genes and co-expressed gene modules revealed a combination of rhizobacteria and aphid induced plant responses. Aphid feeding triggered distinct plant responses in rhizobacteria-inoculated barley compared to controls, in phytohormone, glutathione, and phenylpropanoid pathways within 24 hours. By day 7, stronger responses were observed in phenylpropanoid and nutrient pathways. By day 21, changes occurred in flavonoid pathways and genes related to tissue damage and repair. C_LIO_LIOur study suggests that rhizobacteria inoculation of barley against aphids is dynamic and acts through several molecular pathways to induce plant resistance (defences) and tolerance (nutrition and growth) to aphids. Future research holds promise for exploiting these interactions for sustainable crop protection and pest management in agriculture. C_LI

plant biology↗

bioRxiv2024

Method and timing of rhizobacteria inoculation to plant roots alters success and strength of aphid suppression

Insect pests cause substantial yield losses globally, necessitating novel pest control approaches beyond chemical pesticides. Rhizobacteria, beneficial root-associated bacteria, present a promising alternative by enhancing plant growth and defences against pests. This study explores the use of sodium alginate encapsulation for precise inoculation of two rhizobacteria, Acidovorax radicis and Bacillus subtilis, to suppress aphid populations on barley (Hordeum vulgare). We optimized a method using 4mm diameter wet-matrix alginate beads for controlled bacterial delivery directly to plant roots. Two experiments evaluated the impact of inoculation methods and timing on aphid suppression. Results indicated that rhizobacteria inoculation via alginate beads at root emergence significantly reduced aphid reproductive output, outperforming seed soaking methods. This suggests that more consistent bacterial establishment and prolonged release from alginate beads enhances plant defence priming. Additionally, alginate bead inoculation demonstrated effective long-term bacterial viability following storage at 4{degrees} C for eight months, supporting potential field application. Our findings highlight the potential of alginate bead-encapsulated rhizobacteria for aphid suppression on barley, but emphasizing the need for precise inoculation timing and placement. This approach offers a robust method for empirical research and practical agricultural application, paving the way for sustainable pest management strategies. Future work should focus on optimizing formulations and understanding plant-microbe interactions to enhance field efficacy.

ecology↗

bioRxiv2024

Rhizobacteria inoculation of plants for reducing insect pests: A meta-analysis on insect behaviour and fitness

Microbial communities in the plant rhizosphere--the soil region closely associated with plant roots-- play critical roles in shaping plant growth, defence, fitness, and ecosystem processes. Inoculation of plants with specific rhizobacteria strains has shown promising potential for increasing crop yields. Rhizobacteria can also induce plant defences, resulting in reduced insect growth and reproduction, and can manipulate plant biochemistry to alter insect host-choice and recruit natural enemies of the insects. We present a meta-analysis examining the impact of rhizobacteria inoculation of plants on insect fitness and behaviour. Our findings indicate that rhizobacteria inoculation generally reduces herbivore fitness and host choice behaviours. However, effect sizes varied significantly depending on type of herbivore (chewing versus sucking), plant host, and rhizobacterial species. Bacillus spp. showed stronger effects than the commonly studied Pseudomonas spp. Rhizobacteria notably reduced traits such as host choice, leaf consumption, survival, and reproduction of chewing herbivores, while primarily impacting sucking herbivores by reducing reproduction. Single-strain inoculants tended to perform better, especially for sucking herbivores, suggesting potential strain incompatibility issues with multi-strain inoculants. Furthermore, field trials showed less impact on insect fitness reduction compared to experiments under controlled conditions, possibly due to soil diversity and environmental factors affecting inoculant persistence. Despite, very limited experimental data, studies observed that rhizobacteria inoculation of plants can attract parasitoid wasps and predators to the plants. These results underscore the need for considering broader environmental interactions when developing effective rhizobacteria-based pest management strategies. Understanding specific and generalist rhizosphere interactions can aid in developing synthetic microbial communities with broad protective functions across various plants and environments.

ecology↗

bioRxiv2023

Microbe-induced plant resistance against insect pests depends on timing of inoculation, but is consistent across climatic conditions

O_LITo cope with abiotic and biotic stressors, plants have developed mutualistic associations with beneficial soil microbes, but little is known about how (extreme) abiotic conditions impact on microbe-induce resistance to insect herbivores. C_LIO_LIExtreme temperatures are often accompanied by extremes in plant water availability, which together reduce plant growth and change plant physiology. There are potential consequences for increasing plant susceptibility to biotic stresses, and this poses a real challenge for plant productivity. C_LIO_LIWe evaluated how the effects of beneficial soil bacteria (Acidovorax radicis) on barley plant growth and resultant resistance against aphid infestation (Sitobion avenae) were impacted by a single heatwave event across a plant water availability gradient. We also tested if timing of bacterial inoculation (before or after the heatwave) affected bacteria-plant interactions on aphids. C_LIO_LIWe found that heatwaves affected plant biomass allocation from aboveground to belowground tissues. Inoculation with A. radicis led to reduction of aphid numbers, but depended on timing of inoculation, and led to stronger resistance when inoculations occurred closer to aphid infestation. Remarkably, microbe-induced resistance against aphids was consistent across heatwave and water availability treatments. C_LIO_LIThis study provides evidence that beneficial plant-bacteria interactions may represent a potential solution for sustainable agricultural practices to enhance plant growth and response to insect pests under climate change. Future field trials should investigate the consistency of beneficial effects reported here for a better understanding of multispecies interactions in the context of global change. C_LI

ecology↗

bioRxiv2023

Geographic distribution of terpenoid chemotypes in Tanacetum vulgare mediates tansy aphid occurrence and abundance

AimIntraspecific variations of specialized metabolites in plants, such as terpenoids, are used to determine chemotypes. Tansy (Tanacetum vulgare L.) exhibits diverse terpenoid profiles, that affect insect communities. However, it is not fully known whether patterns of their chemical composition and associated insects vary on a large scale. Here, we investigated the geographic distribution of mono- and sesquiterpenoid chemotypes in tansy leaves and the effects of these chemotypes on colonization by insect communities across Germany. MethodsWe sampled tansy leaves from 26 sites along a north-south and west-east transect in Germany. Leaves from ten plants with and five plants without aphids was collected from each site. Hexane-extracted metabolites from leaf tissues were analysed by gas chromatography-mass spectrometry (GC-MS). Plant morphological traits, aphid occurrence and abundance, and occurrence of ants were recorded. The effect of plant chemotype, plant morphological parameters, and site parameters such as temperature and precipitation on insect occurrences were analysed. ResultsPlants clustered into four monoterpenoid and four sesquiterpenoid chemotype classes. Monoterpene classes differed in their latitudinal distribution, whereas sesquiterpenes were more evenly distributed across the transect. Aphid and ant occurrence were influenced by monoterpenoids and specific traits. Plants of monoterpenoid class 1 were colonized by Metopeurum fuscoviride and ants significantly more often than expected by chance compared to plants from monoterpenoid class 4. Aphid abundance was negatively affected by host plant height, and increasing average annual temperature positively influenced the occurrence of ants. ConclusionWe found significant geographic differences in the chemodiversity of tansy and show that monoterpenoids affect aphid and ant occurrence, while host plant height can influence aphid abundance. We show that geographic variation in plant chemistry and morphology influences insect communities assemblage on tansy plants.

ecology↗

bioRxiv2023

Floral presence and flower identity alter cereal aphid endosymbiont communities on adjacent crops

O_LIFloral plantings adjacent to crops fields can recruit populations of natural enemies by providing flower nectar and non-crop prey to increase natural pest regulation. Observed variation in success rates might be due to changes in the unseen community of protective endosymbionts hosted by many herbivorous insects, which can confer resistance to various specialist natural enemies, e.g. parasitoid wasps. Reduced insect control may occur if highly protective symbiont combinations increase in frequency via selection effects, and this is expected to be stronger in lower diversity systems. C_LIO_LIWe used a large-scale field trial to analyse the bacterial endosymbiont communities hosted by cereal aphids (Sitobion avenae) collected along transects into strip plots of barley plants managed by either conventional or integrated (including floral field margins and reduced inputs) methods. In addition, we conducted an outdoor pot experiment to analyse endosymbionts in S. avenae aphids collected on barley plants that were either grown alone or alongside one of three flowering plants, across three time points. C_LIO_LIIn the field, aphids hosted up to four symbionts. The abundance of aphids and parasitoid wasps was reduced towards the middle of all fields while aphid symbiont species richness and diversity decreased into the field in conventional, but not integrated, field-strips. The proportion of aphids hosting different symbiont combinations varied across cropping systems, with distances into the fields, and were correlated with parasitoid wasp abundances. C_LIO_LIIn the pot experiment, aphids hosted up to six symbionts. Flower presence increased natural enemy abundance and diversity, and decreased aphid abundance. The proportion of aphids hosting different symbiont combinations varied across the flower treatment and time, and were correlated with varying abundances of the different specialist parasitoid wasp species recruited by different flowers. C_LIO_LISynthesis and applications. Floral plantings and flower identity can have community-wide impacts on the combinations of bacterial endosymbionts hosted by herbivorous insects. Our work highlights the potential of within-season selection for symbiont-mediated pest resistance to natural enemies with biological control impacts. This could be mitigated through increased recruitment of diverse natural enemies by incorporating functional diversity of floral resources into the environment. C_LI

ecology↗

bioRxiv2022

Soil microbe-induced plant resistance alters aphid inter-genotypic competition leading to rapid evolution with consequences for plant growth and aphid abundance

O_LIPlants and insect herbivores are two of the most diverse multicellular groups in the world, and both are strongly influenced by interactions with the belowground soil microbiome. Effects of reciprocal rapid evolution on ecological interactions between herbivores and plants have been repeatedly demonstrated, but it is unknown if (and how) the soil microbiome could mediate these eco-evolutionary processes. C_LIO_LIWe tested the role of a plant-beneficial soil bacterium (Acidovorax radicis) in altering eco-evolutionary interactions between sap-feeding aphid herbivores (Sitobion avenae) feeding on barley (Hordeum vulgare). We reared two aphid genotypes separately or together on three barley varieties that were inoculated with or without A. radicis bacteria. In the first experiment we counted the aphid number and plant biomass after 7, 14 and 21 days of aphid growth, while in a second experiment we counted and removed offspring every 1-2 days to assess aphid longevity and fecundity. C_LIO_LIResults showed that A. radicis increased plant growth and suppressed aphids of both genotypes. The strength of effect was dependent on aphid genotype and barley variety, while the direction of effect was altered by aphid population mixture. Fescue aphids experienced increased growth when they were sharing the plant with Sickte aphids on inoculated plants; this increase was not seen in the control plants without A. radicis and was only apparent after 14 days of aphid population growth. C_LIO_LIPlant inoculation with A. radicis reduced aphid survival (reduced number of reproductive days) and fecundity (reduced daily reproductive output for surviving aphids). In the second experiment, when density was controlled, Fescue aphids did not experience increased reproduction in mixed populations, suggesting this is a density-dependent effect. Using Lotka-Volterra modelling, we demonstrated that A. radicis inoculation decreased aphid population stability as it increased inter-genotype competition but decreased the intra-genotype competition (likely through reduced population density). C_LIO_LIOur work demonstrates the important role that plant-associated microbiomes can have in mediating eco-evolutionary interactions between herbivores and host plants. C_LI

ecology↗

bioRxiv2019

A meta-analysis on the benefits and costs of hosting secondary endosymbionts in sap-sucking insects

Herbivorous insects host various bacteria that help them to feed, grow, and survive. Sap-sucking insects, in particular, feed on a nutrient-poor resource and have evolved obligate symbioses with nutritional bacteria for survival. Additionally, sap-sucking insects have formed facultative associations with bacterial symbionts that are not essential for growth and survival but assumed to confer some benefits, such as resistance to natural enemies. Several recent reviews have highlighted the importance of these symbionts in understanding their hosts biology, but currently there is a lack of a quantitative and systematic analysis of the published evidences exploring whether the different endosymbionts are actually beneficial or not. In this meta-analysis we explored the potential costs and benefits associated with hosting facultative endosymbionts in sap-sucking insects. Our first result is that most of the empirical experimental data information is limited to a few species of aphid and one species of whiteflies. Through the meta-analysis we showed that hosting symbionts generally leads to costs through increased development time, reduced longevity, and reduced fecundity, and benefits via increased resistance to parasitic wasps in sap-sucking insects. However, the impact of these costs and benefits was strongly insect and symbiont species dependent. Many of the insects studied are agricultural pests, and understanding the impact of bacterial symbionts on their hosts across different environments can benefit sustainable management of greenhouses and agricultural land.

ecology↗