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Perina nuda (Lepidoptera: Lymantriidae) is a serious pest of banyan trees (Ficus spp.), which is distributed in South China, but little is known about the host preference on the different banyan tree species. To address this gap, we conducted experiments to investigate larval feeding preferences, assessing the impact of feeding experience in both choice and no-choice conditions. Fifth and sixth instars were exposed to 4 banyan species, and food intake, feeding area, and relative ingestion index were measured. Our findings reveal that Ficus concinna was the preferred host of fifth instars in choice tests, while sixth instars exhibited a preference for this host in no-choice tests. In contrast, fifth instars did not display a significant preference for any of the 4 species in no-choice tests. However, sixth instars fed on F. microcarpa, F. altissima, and F. concinna continued to exhibit a preference for the original host. These observations indicate that larval feeding preference changes with instar, and feeding experience contributes to a preference for the original host. Consequently, the feeding preference of P. nuda larvae is influenced by multiple factors, including instar and previous feeding experience. These findings enhance our understanding of P. nuda's ecological interactions and its potential impact on various banyan tree species.

Rhizobial diversity and host preferences were assessed in 65 native Fynbos legumes of the papilionoid legume tribes Astragaleae, Crotalarieae, Genisteae, Indigofereae, Millettieae, Phaseoleae, Podalyrieae, Psoraleeae and Sesbanieae. Sequence analyses of chromosomal 16S rRNA, recA, atpD and symbiosis-related nodA, nifH genes in parallel with immunogold labelling assays identified the symbionts as alpha- (Azorhizobium, Bradyrhizobium, Ensifer, Mesorhizobium and Rhizobium) and beta-rhizobial (Burkholderia) lineages with the majority placed in the genera Mesorhizobium and Burkholderia showing a wide range of host interactions. Despite a degree of symbiotic promiscuity in the tribes Crotalarieae and Indigofereae nodulating with both alpha- and beta-rhizobia, Mesorhizobium symbionts appeared to exhibit a general host preference for the tribe Psoraleeae, whereas Burkholderia prevailed in the Podalyrieae. Although host genotype was the main factor determining rhizobial diversity, ecological factors such as soil acidity and site elevation were positively correlated with genetic variation within Mesorhizobium and Burkholderia, respectively, indicating an interplay of host and environmental factors on the distribution of Fynbos rhizobia. This study is the most comprehensive phylogenetic assessment of rhizobia within the Fynbos biome, showing that legumes are specifically associated with Burkholderia and Mesorhizobium, the latter underestimated within Fynbos soils.

Background Pulses are essential components of agricultural production systems, post-harvest losses caused by storage insect pests remain a major challenge. Callosobruchus maculatus (F.) is a widespread pest of stored legumes, and its host preference is influenced by seed type and associated physico-biochemical traits. This study examined the determinants of C. maculatus preference among nine legume species using controlled laboratory assays and seed trait analyses. Results Under no-choice conditions, chickpea ( Cicer arietinum L), pigeon pea ( Cajanus cajan L.) , and moth bean ( Vigna aconitifolia (Jacq.) Maréchal) supported high oviposition, larval development, and adult emergence, suggesting their overall biological suitability as hosts. In contrast, the common bean ( Phaseolus vulgaris L.) was the most preferred oviposition substrate under free-choice conditions but exhibited poor hatching and emergence, indicating its role as an oviposition trap. Black gram ( Vigna mungo L.) , soybean ( Glycine max (L.) Merr) , and moth bean, though less preferred, supported high post-embryonic success, revealing latent susceptibility. Green gram ( Vigna radiata L. ), black gram, red gram, cowpea ( Vigna unguiculata L. ), and moth bean exhibited high intrinsic suitability, reflected by positive growth indices, shorter developmental durations (notably in black gram and green gram), and balanced oviposition with adult longevity. Conclusion Principal component analysis identified two major axes of host discrimination: (i) physical traits governing oviposition preference and (ii) biochemical composition determining larval development. Seeds with greater surface area, thinner seed coats, and moderate sphericity were favoured for egg deposition, whereas high protein and carbohydrate content enhanced larval growth. In contrast, anti-nutritional factors such as tannins and phytic acid negatively affected larval performance. These findings underscore the significance of integrating physico-biochemical resistance traits into legume breeding and storage management strategies to reduce bruchid-related post-harvest losses.

Background Chlamydia (C.) psittaci , the causative agent of avian chlamydiosis and human psittacosis, is a genetically heterogeneous species. Its broad host range includes parrots and many other birds, but occasionally also humans (via zoonotic transmission), ruminants, horses, swine and rodents. To assess whether there are genetic markers associated with host tropism we comparatively analyzed whole-genome sequences of 61 C. psittaci strains, 47 of which carrying a 7.6-kbp plasmid. Results Following clean-up, reassembly and polishing of poorly assembled genomes from public databases, phylogenetic analyses using C. psittaci whole-genome sequence alignment revealed four major clades within this species. Clade 1 represents the most recent lineage comprising 40/61 strains and contains 9/10 of the psittacine strains, including type strain 6BC, and 10/13 of human isolates. Strains from different non-psittacine hosts clustered in Clades 2– 4. We found that clade membership correlates with typing schemes based on SNP types, ompA genotypes, multilocus sequence types as well as plasticity zone (PZ) structure and host preference. Genome analysis also revealed that i) sequence variation in the major outer membrane porin MOMP can result in 3D structural changes of immunogenic domains, ii) past host change of Clade 3 and 4 strains could be associated with loss of MAC/perforin in the PZ, rather than the large cytotoxin, iii) the distinct phylogeny of atypical strains (Clades 3 and 4) is also reflected in their repertoire of inclusion proteins (Inc family) and polymorphic membrane proteins (Pmps). Conclusions Our study identified a number of genomic features that can be correlated with the phylogeny and host preference of C. psittaci strains. Our data show that intra-species genomic divergence is associated with past host change and includes deletions in the plasticity zone, structural variations in immunogenic domains and distinct repertoires of virulence factors.

Through co‐evolutionary adaptation, phytopathogenic fungi have evolved specialised host preference mechanisms to optimise infection efficacy. Fungi of the Valsa genus infect various Rosaceae fruit trees, with Valsa mali exhibiting a marked host preference for apple trees, while Valsa pyri preferentially colonises pear trees. The divergent secondary metabolite biosynthetic gene clusters (SMBGCs) between these two species may serve as key determinants of their distinct host preferences. In this study, VmPKS5, a polyketide synthase, was identified as a key factor influencing the host preference of V. mali, which is the main pathogen of apple Valsa canker (AVC). Deletion of VmPKS5 greatly reduced the virulence of V. mali in apple trees, but not in pear trees. Deletion of VmPKS5 completely abolished the production of the toxin p‐coumaric acid ethyl ester (p‐CAEE). Exogenous p‐CAEE application partly restored the virulence of ΔVmPKS5 and enhanced the virulence of the wild‐type strain of V. mali. Crucially, heterologous expression of VmPKS5 in V. pyri increased its virulence towards apple trees by production of p‐CAEE during infection. Notably, V. mali can uptake double‐stranded RNA (dsRNA), and exogenous spray of VmPKS5‐dsRNA significantly inhibited the infection by V. mali. This study provides new perspectives on host preference mechanisms of fungal pathogens and green disease control of tree disease by dsRNA fungicides. VmPKS5 mediates the virulence and host preference of Valsa mali by regulating the synthesis of p‐coumaric acid ethyl ester (p‐CAEE). Meanwhile, exogenous application of VmPKS5‐dsRNA significantly suppresses the infection caused by V. mali.

The forest canopy is home to a rich biota. One salient feature are the dynamics of the habitat‐building trees, which are growing and eventually vanishing. Tree species strongly differ in growth rates, final size and longevity. Nevertheless, these inherent dynamics have been a blind spot in studies on host specificity of vascular epiphytes (vascular plants dwelling on trees without parasitizing them)—not least because tree growth rates and longevity are usually unknown in highly diverse tropical forests. The present study aims at tackling this blind spot. We compared epiphyte abundances (>23,000 individuals) found on 285 individuals of four focal tree species in a lowland moist forest in Panama. Data on repeated dbh censuses from a permanent tree plot provided the unique opportunity to estimate the age of our sampled trees. We compared the relative importance of tree longevity for host biases with that of other host tree characteristics, namely microclimatic conditions and bark acidity, rugosity and stability. The studied tree species differ in host quality and epiphyte species partly differ in host preferences. The conclusions concerning relative host tree quality depend hugely on whether or not different tree growth rates are considered. Comparing these conclusions allows important insights into the role of tree longevity in shaping epiphyte communities. Relating tree trait differences to the observed distributions of epiphytes among the focal tree species shows how the simultaneous action of various tree characteristics causes host biases. Synthesis. This study highlights the substantial but, up to now, hidden role of different tree growth rates for host tree specificity of vascular epiphytes. Future investigations need to consider this possibly confounding factor adequately to avoid spurious conclusions. Differences in tree growth rates have been a blind spot in studies on host specificity of vascular epiphytes. We compared epiphyte abundances on four tree species in a lowland moist forest. Host quality ranking depends hugely on whether tree size or age is used as a covariate. Future investigations need to consider different tree growth rates to avoid spurious conclusions.

Members of Fusarium sambucinum species complex (FSAMSC), major mycotoxigenic phytopathogens, affect cereal crops such as wheat and rice. The predominant members of FSAMSC, F. graminearum , F. asiaticum , and F. meridionale , are distinguished by their trichothecene chemotypes, primarily nivalenol (NIV) and deoxynivalenol (DON) chemotype. While DON has been linked to virulence in certain FSAMSC species, NIV chemotypes exhibit increased aggressive in rice, whereas DON chemotypes preferentially infect wheat. However, the genetic factors driving these chemotype–host associations remain unclear. This study investigated the genetic linkage between DON/NIV chemotype and host preference through molecular and phenotypic analyses. RNA sequencing revealed host‐dependent differential expression of trichothecene biosynthetic ( TRI ) genes during wheat and rice infection by DON and NIV chemotypes. Sequencing confirmed that NIV chemotypes carry a functional TRI13 gene encoding a trichothecene C‐4 hydroxylase, whereas DON chemotypes harbour a nonfunctional TRI13 pseudogene ( ψTRI13 ). Genetic manipulation of TRI13 confirmed its role in determining DON/NIV chemotype and host preference. TRI13 deletion in NIV strains converted them into a DON chemotype, while complementation of ψTRI13 in DON strains generated a hybrid chemotype producing both toxins, with the 3‐acetyl‐DON chemotype showing a more pronounced hybrid profile than the 15‐acetyl‐DON chemotype. Pathogenicity assays revealed that TRI13 deletion reduced virulence in rice but enhanced colonisation in wheat. Conversely, TRI13 complementation increased rice aggressiveness and decreased wheat infection. This study provides the first genetic evidence for host preference driven by DON/NIV chemotypes in F. graminearum , F. asiaticum , and F. meridionale , offering insights for improved mycotoxin surveillance and disease management strategies.

Influences of soil environment and willow host species on ectomycorrhizal fungi communities was studied across an hydrologic gradient in temperate North America. Soil moisture, organic matter and pH strongly predicted changes in fungal community composition. In contrast, increased fungal richness strongly correlated with higher plant-available phosphorus. The 93 willow trees sampled for ectomycorrhizal fungi included seven willow species. Host identity did not influence fungal richness or community composition, nor was there strong evidence of willow host preference for fungal species. Network analysis suggests that these mutualist interaction networks are not significantly nested or modular. Across a strong environmental gradient, fungal abiotic niche determined the fungal species available to associate with host plants within a habitat. Soil moisture, pH and organic matter alter the ectomycorrhizal fungal species present in communities regardless of host plant identity. Graphical Abstract Figure. Soil moisture, pH and organic matter alter the ectomycorrhizal fungal species present in communities regardless of host plant identity.

ABSTRACT The number of plant species regarded as non-mycorrhizal increases at higher latitudes, and several plant species in the High-Arctic Archipelago Svalbard have been reported as non-mycorrhizal. We used the rRNA ITS2 and 18S gene markers to survey which fungi, as well as other micro-eukaryotes, were associated with roots of 31 arctic plant species not usually regarded as mycorrhizal in Svalbard. We assessed to what degree the root-associated fungi showed any host preference and whether the phylogeny of the plant hosts may mirror the composition of root-associated fungi. Fungal communities were largely structured according to host plant identity and to a less extent by environmental factors. We observed a positive relationship between the phylogenetic distance of host plants and the distance of fungal community composition between samples, indicating that the evolutionary history of the host plants plays a major role for which fungi colonize the plant roots. In contrast to the ITS2 marker, the 18S rRNA gene marker showed that chytrid fungi were prevalently associated with plant roots, together with a wide spectrum of amoeba-like protists and nematodes. Our study confirms that arbuscular mycorrhizal (AM) fungi are present also in arctic environments in low abundance. Community composition of arctic root-associated fungi mirrors host plant phylogeny.

Parasitoids of wood borers and bark beetles rarely encounter different host species simultaneously in nature, so whether they exhibit any preferences for particular species, and the relative suitability of different host species is unclear. Sclerodermus guani (Hymenoptera: Bethylidae) is an ectoparasitoid of cerambycid larvae and has also been reported from multiple host species. In this study we used S. guani as a model parasitoid to evaluate preferences for different host species. Moreover, we determined how levels of intraspecific interaction amongst S. guani adults affect host species preference, and subsequent mortality of those different hosts. S. guani adults display high levels of preference for particular hosts and cause rates of non-reproductive mortality of Aromia bungii (Coleoptera: Cerambycidae) and Monochamus alternatus (Cerambycidae) larvae that are higher than the reproductivity mortality of both hosts. Under different parasitoid densities interaction, S. guani always preferred A. bungii and Monochamus saltuarius (Cerambycidae) and varied in its responses to Thyestilla gebleri (Cerambycidae) and M. alternatus . In addition, the mortalities of single T. gebler i , A. bungii or M. saltuarius larvae caused by the parasitoids (1–3 individuals) were all 100%. These results can help us to better understand S. guani host choice behavior and its biological control potential.