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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 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.

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.

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.

Since the 1990s, increasing populations of a blood feeding land leech (Haemadipsa japonica) have become a serious issue in several Japanese prefectures, and it may be caused by the increases in sika deer (Cervus nippon) populations seen over the last quarter of the century. Therefore, this study aimed to reveal the host animal species of H. japonica using iDNA (vertebrate DNA isolated from invertebrates) and to test the hypothesis that the increasingly widespread distribution of sika deer results in increased H. japonica populations through changes to the host–parasite interface. We amplified mitochondrial DNA 16S ribosome RNA fragments from iDNA isolated from the blood clots of H. japonica collected across Japan. We identified 17 host animal species, including four orders of Mammalia (Carnivora, Artiodactyla, Rodentia, and Lagomorpha) and two orders of Amphibia (Caudata and Anura). The sika deer was the dominant host species of H. japonica. Additionally, the host animal species composition of H. japonica differed according to the presence or absence of sika deer. In the sites where sika deer were not found, Anura (frog) species were the most commonly identified hosts of H. japonica. These results suggest that the increases in H. japonica populations might have occurred via a change in host preference to sika deer. This change might be driven by the increases in sika deer populations and subsequent increase in the frequency that H. japonica uses the sika deer as easy prey, as well as by sika deer providing more reproductive energy per blood meal than blood meal from frog species. The present study suggests that a more widespread distribution of sika deer resulted in an increase in H. japonica through a change in the host–parasite interface. Therefore, management that focuses on decreasing sika deer populations would likely be an effective method for the reduction of H. japonica populations. This paper revealed the host animal species of a blood land leech (Haemadipsa japonica) in Japan using vertebrate DNA isolated from blood feeding invertebrates (iDNA). Additionally, the host animal species of the leech differed according to the presence or absence of sika deer.

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.

Predation risk posed by natural enemies can alter pest performance. In our previous study, we found Menochilus sexmaculatus provides risk cues to melon aphids, resulting in increased numbers of winged aphids. However, the effects of predation risk on multiple traits including behavior, physiology, growth rate, and reproductive capacity of pests are not clear. This study examined the effects of predation risk on host preference, the activities of two important defense enzymes (CAT and SOD), longevity, and offspring production. The Y-tube trial results showed that the risk of M. sexmaculatus significantly altered the host preference of the aphids, leading to avoidance behavior. When exposed to M. sexmaculatus for a long period (24 h), the reproductive period and offspring production were significantly decreased, and adult longevity was significantly shortened. The defense enzyme activities of SOD and CAT, as well as the MDA content (which is considered a marker of oxidative stress and cellular damage) in the aphids, significantly increased under M. sexmaculatus risk. The compounds of M. sexmaculatus extracted with n-hexane and volatile compounds collected with HS-SPME were analyzed by GC-MS, and when combined with the behavior response experiment, the results showed that the alkane compounds n-henicosane, n-docosane, n-tricosane, n-pentacosane, and n-hentriacontane may contribute to the impact of predation risk. The results will be helpful in the comprehensive evaluation of the ability of lady beetles to affect the aphid population, and provide new ideas for using these compounds in aphid control.

African horse sickness (AHS) was reported as an outbreak in Thailand in 2020. Hematophagous insects from the genus Culicoides are the suspected vector responsible for AHS transmission. Horses in Hua Hin district, Prachuab Khiri Khan province, Thailand, were affected and died from AHS in 2020. However, the potential Culicoides species and its host preference blood meal in the affected areas are unknown. To investigate the potential vectors of AHS, Culicoides were collected using ultraviolet light traps placed near horse stables. Six horse farms, including five farms with AHS history and one farm without AHS history, were included in this study. Morphological and molecular identification of the Culicoides species was performed. Polymerase chain reaction (PCR) targeting the cytochrome b oxidase I (COXI) gene for confirmation of the Culicoides species, identification of the prepronociceptin (PNOC) gene for host preference blood meal, and bidirectional sequencing were conducted. Consequently, 1008 female Culicoides were collected, consisting of 708 and 300 samples captured at positions A and B at a distance of <2 and >5 m from the horse, respectively. Twelve Culicoides species identified by morphology were noted, including C. oxystoma (71.92%), C. imicola (20.44%), C. actoni (2.28%), C. flavipunctatus (1.98%), C. asiana (0.99%), C. peregrinus (0.60%), C. huffi (0.60%), C. brevitarsis (0.40%), C. innoxius (0.30%), C. histrio (0.30%), C. minimus (0.10%), and C. geminus (0.10%). The PCR detection of the Culicoides COXI gene confirmed Culicoides species in 23 DNA samples. PCR targeting the PNOC gene revealed that the Culicoides collected in this study fed on Equus caballus (86.25%), Canis lupus familiaris (6.25%), Sus scrofa (3.75%), and Homo sapiens (3.75%) for their blood meal. Human blood was identified from two samples of C. oxystoma and a sample of C. imicola. Three dominant species including C. oxystoma, C. imicola, and C. actoni that were reported in the Hua Hin area prefer to feed on horse blood. Moreover, C. oxystoma, C. imicola, and C. bravatarsis also feed on canine blood. This study revealed the species of Culicoides in Hua Hin district, Thailand, after the AHS outbreak.