Host Preference Research Articles

Synhospitality of eriophyoid mites (Acariformes, Eriophyoidea): taxonomic analysis of gall-forming mite species complexes on boreal woody dicotyledons

Microscopic mites of the Eriophyoidea superfamily are characterized by an ability to cause the growth of galls on plants. Synhospital complexes of gall-forming Eriophyoidea (SCGE) species are formed by several species of gall mites coexisting on the same host plant. To assess the phenomenon of synhospitality, we investigated the features of the taxonomic composition and diversity of galls formed by eriophyoid mites on boreal woody dicotyledons and carried out a statistical analysis of the host relationships of different gall mite genera from the Eriophyidae family. We found out that phylogenetically closely related hosts within biogeographically integral territories possess the similar SCGE. During colonization of plants, gall mites demonstrate a high ability to cryptic speciation, which leads to genesis of morphologically similar mite species that cause the formation of different types of galls. Host preferences of gall mites belonging to the different supergenera groups play an important role in the formation of the SCGE, which determines the differences in mite taxa spectra associated with hosts from different families. In general, the results of the work demonstrate that the synhospitality of Eriophyoidea is not a random process, but is the result of a long-term coadaptation in the “parasite–host” system. This is one of the phenomena reflecting the stages of the global historical process of the colonization of Embriophyta plants by mites of the Eriophyoidea superfamily.

Ovipositional Preference of <i>Rhynchophorus ferrugineus</i> (Olivier) in Palm Species in Goa

Red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) is devastating pest in commercial and ornamental palms. The study was conducted to find out ovipositional preference of R. ferrugineus in seven palm species. Result revealed that the fish tail palm (Caryota cumingii Lodd.) is highly preferred host for oviposition by R. ferrugineus followed by coconut (Cocos nucifera L.). Toddy palm (Borassus flabellifer L.) was found to be least preferred by R. ferrugineus for oviposition. The ornamental palm, cane palm Dypsis lutescens (H. Wendl.) Beentje and J. Dransf is found as new preferred host for oviposition in free choice test.

Host plant selection is linked to performance in Phthorimaea absoluta (Lepidoptera: Gelechiidae).

The evolution of oviposition preference in insects is considered a key evolutionary strategy in the context of host-plant interaction. It is hypothesized that insects maximize the survival and fitness of the subsequent generations by preferring specific host plant(s), known as the "preference-performance hypothesis." In this study, we tested whether adult host preference reflects the immature performance in an oligophagous insect, Phthorimaea absoluta Meyrick, a rapidly emerging invasive pest in Asia, Africa, and Europe. Based on a preliminary survey of the potential host plants of P. absoluta, we selected 6 Solanaceae species, namely, tomato, potato, eggplant, black nightshade, sweet pepper, and tobacco, for the oviposition preference studies. The results indicated that the tomato was the most preferred host in no-, dual- and multiple-choice assays, followed by potato, eggplant, and black nightshade. Subsequently, the insect life-table parameters were found to be superior on tomato compared to other hosts. The order of oviposition preference on the host plants was strongly correlated with the life-table parameters of P. absoluta. Thus, we provide clear evidence for the preference-performance hypothesis in the host selection behavior of P. absoluta. We also emphasize the necessity of conducting oviposition behavior research at various geographic locations to develop tailor-made integrated pest management programs.

Host preference patterns in domestic and wild settings: Insights into Anopheles feeding behavior.

The adaptation of Anopheles malaria vectors to domestic settings is directly linked to their ability to feed on humans. The strength of this species-habitat association is unequal across the species within the genus, with the major vectors being particularly dependent on humans. However, our understanding of how blood-feeding behavior interacts with and adapts to environmental settings, including the presence of humans, remains limited. Using a field-based approach, we first investigated Anopheles community structure and feeding behavior patterns in domestic and sylvatic settings in La Lopé National Park in Gabon, Central Africa. We characterized the preference indices using a dual-host choice sampling approach across mosquito species, habitats, and seasons. We then quantified the plastic biting behavior of mosquito species in each habitat. We collected individuals from 16 Anopheles species that exhibited significant differences in species composition and abundance between sylvatic and domestic settings. The host-seeking behavior also varied among the seven most abundant species. The general attractiveness to each host, human or animal, remained relatively constant for each species, but with significant variations between habitats across species. These variations, to more generalist and to more anthropophilic behavior, were related to seasonal changes and distance from the village, respectively. Finally, we pointed out that the host choice of major malaria vectors changed in the absence of humans, revealing a plastic feeding behavior of these species. This study highlights the effect of humans on Anopheles distribution and feeding evolution. The characterization of feeding behavior in wild and domestic settings provides opportunities to better understand the interplay between genetic determinants of host preference and ecological factors. Our findings suggest that protected areas may offer alternative thriving conditions to major malaria vectors.

Coevolution with hosts underpins speciation in brood-parasitic cuckoos.

Coevolution between interacting species is thought to increase biodiversity, but evidence linking microevolutionary processes to macroevolutionary patterns is scarce. We leveraged two decades of behavioral research coupled with historical DNA analysis to reveal that coevolution with hosts underpins speciation in brood-parasitic bronze-cuckoos. At a macroevolutionary scale, we show that highly virulent brood-parasitic taxa have higher speciation rates and are more likely to speciate in sympatry than less-virulent and nonparasitic relatives. We reveal the microevolutionary process underlying speciation: Hosts reject cuckoo nestlings, which selects for mimetic cuckoo nestling morphology. Where cuckoos exploit multiple hosts, selection for mimicry drives genetic and phenotypic divergence corresponding to host preference, even in sympatry. Our work elucidates perhaps the most common, but poorly characterized, evolutionary process driving biological diversification.

Impact of different host plants on biology and morphometrics of various developmental stages of Papilio demoleus (Linn.)

The comparative studies under laboratory conditions have been carried out to investigate the influence of different alternative host plants viz., bael [Aegle marmelos (L.)], curry leaves [Murraya koenigii (L.) Spreng.], ber (Zizyphus mauritiana Lam.) and lemon [Citrus limon (L.) Burm.f.] on biology and morphometrics of Lemon butterfly, Papilio demoleus (Linn.). The lemon is the most preferred host of P. demoleus used as a controlled experimental host plant. The variations in periods of larval, pupal and rate of emergence into adult have been recorded and found that the lemon was the most preferred host plant on which all the larval stages survived smoothly. The caterpillars when reared on alternative hosts showed an increase in average larval period. The average survival percent of larvae were reported highest on bael leaves, followed by curry leaves and ber leaves. Similar patterns of results were also recorded on the pupal period and rate of emergence with alternative hosts. The morphometric variations in weight, size and colour of caterpillars, pupae and adults were also measured and found in decreasing order of host preferences as lemon[greater than]bael[greater than]curry[greater than]ber.

Seven New Angiospermic Hosts for <i>Orobanche aegyptiaca</i> Pers. (Orobanchaceae)

Seven new hosts of Orobanche aegyptiaca Pers. were recorded from the district of Malda, West Bengal, namely Cicer arietinum (cultivated),Fumaria indica, Argemone mexicana, Leucas indica, Leunaea aspleniifolia, Vernonia cinerea and Digitaria ciliaris (all weeds). From the comparison of ten major morphological characters Launaea asplenigolia is appeared as most preferred host followed by Cicer arietinum, whereas Argemone mexicana is the weakest host.

Sodium valproate promotes low metabolism and high protein expression in CHO-engineered cell lines

Chinese hamster ovary cells are widely used in various biopharmaceutical industries as preferred host cells for the production of recombinant proteins. In an effort to increase yield and reduce production costs, the incorporation of small molecule additives into the culture medium has emerged as an effective approach to augment the expression of recombinant proteins, thus increasing overall efficiency. Here, we examined the impact of five small molecules on protein expression in CHO-engineered cell lines. These molecules included sodium valproate, alanyl-L-tyrosine, ascorbic acid, sodium citrate and ferrous sulphate. Their optimal concentrations were determined through univariate analysis aimed at enhancing cell growth and protein production. Our findings revealed that inoculating cells at a density of 1.0 × 106 cells/mL with the simultaneous addition of sodium valproate at a concentration of 2 mM for 0 h yielded the most favorable results. Notably, while valproate inhibited cell growth in a dose-dependent manner, it simultaneously extended cell culture longevity. Additionally, sodium valproate was observed to decrease glucose consumption, collectively increasing protein expression. In conclusion, our data suggest that sodium valproate is a potent chemical agent capable of increasing the production of recombinant protein in CHO cells. This enhancement is achieved by the modulation of metabolic pathways in CHO-engineered cell lines, thereby facilitating a state of low metabolism and high protein expression.

Effects of Piper aduncum (Piperales: Piperaceae) Essential Oil and Its Main Component Dillapiole on Detoxifying Enzymes and Acetylcholinesterase Activity of Amblyomma sculptum (Acari: Ixodidae).

Amblyomma sculptum is a species of tick in the family Ixodidae, with equids and capybaras among its preferred hosts. In this study, the acaricidal activity of the essential oil (EO) from Piper aduncum and its main component, Dillapiole, were evaluated against larvae of A. sculptum to establish lethal concentration values and assess the effects of these compounds on tick enzymes. Dillapiole exhibited slightly greater activity (LC50 = 3.38 mg/mL; 95% CI = 3.24 to 3.54) than P. aduncum EO (LC50 = 3.49 mg/mL; 95% CI = 3.36 to 3.62) against ticks. The activities of α-esterase (α-EST), β-esterase (β-EST), and glutathione-S-transferase (GST) enzymes in A. sculptum larvae treated with Dillapiole showed a significant increase compared to the control at all concentrations (LC5, LC25, LC50 and LC75), similar results were obtained with P. aduncum EO, except for α-EST, which did not differ from the control at the highest concentration (LC75). The results of the acetylcholinesterase (AChE) activity show an increase in enzyme activity at the two lower concentrations (LC5 and LC25) and a reduction in activity at the two higher, lethal concentrations (LC50 and LC75) compared to the control. These results suggest potential mechanisms of action for these natural acaricides and can provide guidance for the future development of potential plant-derived formulations.

Using Age-Stage Two-Sex Life Tables to Assess the Suitability of Three Solanaceous Host Plants for the Invasive Cotton Mealybug Phenacoccus solenopsis Tinsley.

Phenacoccus solenopsis Tinsley (Hemiptera: Coccomorpha: Pseudococcidae), the cotton mealybug, is an invasive polyphagous species that has been extending its geographic range, posing a conspicuous threat to many Mediterranean crops of economic importance. These include three species of Solanaceae, namely Solanum lycopersicum L. (tomato), Solanum tuberosum L. (potato) and Solanum melongena L. (eggplant) all of which are economically important worldwide. In this study, we used age-stage two-sex life tables to investigate the suitability of these three plant species as hosts for P. solenopsis and to calculate pest fitness, life history parameters and population projection parameters. All tested host plants that were suitable for the pest and eggplant host plant induced a higher fecundity (276.50 ± 10.78 eggs/female), net reproductive rate (R0) (243.32 ± 15.83 offspring/female) and finite rate of increase (λ) (1.18 ± 0.0043 day-1) and more extended adult longevity (males: 6.50 ± 0.34 days and females: 24.15 ± 0.50 days). Population growth predictions over a period of 90 days of infestation, commencing with an initial population of 10 eggs showed that adult population size was 674,551 on tomato, 826,717 on potato and 355,139 on eggplant. Our data on plant host preference of P. solenopsis will aid the development of appropriate management strategies and achieve successful control of this invasive pest in key Mediterranean crop systems.

Host preferences of an invasive specialist herbivore and native predators on chemically defended plants

Abstract Herbivorous insects generally choose host plants that optimize their growth. However, many specialists choose chemically defended host plants that slow their growth, prioritizing protection from natural enemies. Invasive specialist herbivores may have an added advantage in their non‐native range where they lack co‐evolved specialist natural enemies, in addition to being unpalatable to generalist predators. Here, we explore the diet preferences of the invasive yellowmargined leaf beetle, Microtheca ochroloma and those of native natural enemies. We measured M. ochroloma preferences among six Brassica cultivars varying in glucosinolate concentrations. In both field and laboratory experiments, M. ochroloma preferred the relatively less defended host plants, mizuna and Chinese cabbage. M. ochroloma grew quickest on mizuna. Generalist predators also preferred to eat M. ochroloma larvae that had been fed mizuna in choice trials, yet in the field, predatory insects were least commonly found on mizuna, and most commonly found on plants dominated by native herbivores. M. ochroloma consumes plants that increase their susceptibility to predators, but predation pressure in the field appears to be generally low. Our results suggest that invasive specialist herbivores may prioritize growth over protection against natural enemies. Weak top‐down regulation of specialist herbivore invaders might enable them to exploit less‐defended host plants in their novel range that facilitate faster growth and exacerbate crop damage. Invasive pests may be more effectively managed by leveraging plant preferences in the novel host range in trap crop systems.

The role of the major chemosensory organs in the host-seeking activity of Anopheles coluzzii (Diptera: Culicidae).

Anopheles coluzzii (Coetzee & Wilkerson) and its sibling species Anopheles gambiae s.s. (Giles) are highly anthropophilic and among the major malaria vectors in sub-Saharan Africa. Mosquitoes use various senses to find hosts, but rely primarily on olfaction. Therefore, the mosquito olfactory system has been studied extensively, including a variety of studies comparing chemosensory gene expression between An. coluzzii and its zoophilic sibling species Anopheles quadriannulatus (Theobald). These studies revealed species-specific chemosensory gene expression in the antennae and maxillary palps, which raised the question of a potential role for the palps in determining species-specific host preferences. To answer this question, we mechanically ablated the antennae, maxillary palps, and labella, and ran both control and ablated mosquitoes through a dual-port olfactometer. While we aimed to identify the organs responsible for vertebrate host choice, the ablated mosquitoes exclusively responded to human odor, so we were unable to do so. However, we were able to refine our understanding of the roles of these organs in host-seeking activation (leaving the release cage) as well as odor response (entering an odor port). As expected, the antennae are the most important organs to both behaviors: activation was roughly halved and vertebrate odor response was abolished in antennae-ablated mosquitoes. Maxillary palp ablation had little impact on activation, but reduced odor response to a similar degree as the exclusion of CO2. Finally, while labellar ablation dramatically reduced activation (probably associated with the inability to feed), it had little impact on odor response, suggesting that any labellar role in host choice is likely not olfactory.

Performance and preference of larval parasitoid, Microplitis pallidipes (Hymenoptera: Braconidae), on 2 Spodoptera pest species.

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and Spodoptera litura (Fabricius) are the main pests on corn (Poaceae: Gramineae). The performance of the larval wasp, Microplitis pallidipes Szépligeti (Hymenoptera: Braconidae), was reported on S. frugiperda and S. litura. In this study, we evaluated host selectivity, constructed an age-stage, 2-sex life table, and assessed the pest control potential of M. pallidipes against these 2 pests under laboratory conditions. In a 2-choice host preference experiment, M. pallidipes exhibited a stronger preference for S. frugiperda over S. litura and a distinct preference for second instars. We also investigated the parasitism of females that were either unfed or fed with 10% honey-water solution under different host densities and found that the highest parasitism rate was observed when M. pallidipes were fed with honey-water solution on the first day after mating and a presented female wasp:host ratio of 1:90. In a nonselective assay, M. pallidipes successfully completed a full generation on both hosts. However, the parasitoids exhibited higher fitness and population growth potential when reared on S. frugiperda, with a net reproductive rate (R0) of 24.24, an intrinsic rate of increase (r) of 0.20 per day, a finite rate of increase (λ) of 1.23 per day, and a mean generation time (T) of 15.69 days. This study elucidates the performance of M. pallidipes on 2 Spodoptera host species and offers insights into its biological control potential on lepidopteran pests.

Which SDM Model, CLIMEX vs. MaxEnt, Best Forecasts Aeolesthes sarta Distribution at a Global Scale under Climate Change Scenarios?

A precise evaluation of the risk of establishing insect pests is essential for national plant protection organizations. This accuracy is crucial in negotiating international trade agreements for forestry-related commodities, which have the potential to carry pests and lead to unintended introductions in the importing countries. In our study, we employed both mechanistic and correlative niche models to assess and map the global patterns of potential establishment for Aeolesthes sarta under current and future climates. This insect is a significant pest affecting tree species of the genus Populus, Salix, Acer, Malus, Juglans, and other hardwood trees. Notably, it is also categorized as a quarantine pest in countries where it is not currently present. The mechanistic model, CLIMEX, was calibrated using species-specific physiological tolerance thresholds, providing a detailed understanding of the environmental factors influencing the species. In contrast, the correlative model, maximum entropy (MaxEnt), utilized species occurrences and spatial climatic data, offering insights into the species' distribution based on observed data and environmental conditions. The projected potential distribution from CLIMEX and MaxEnt models aligns well with the currently known distribution of A. sarta. CLIMEX predicts a broader global distribution than MaxEnt, indicating that most central and southern hemispheres are suitable for its distribution, excluding the extreme northern hemisphere, central African countries, and the northern part of Australia. Both models accurately predict the known distribution of A. sarta in the Asian continent, and their projections suggest a slight overall increase in the global distribution range of A. sarta with future changes in climate temperature, majorly concentrating in the central and northern hemispheres. Furthermore, the models anticipate suitable conditions in Europe and North America, where A. sarta currently does not occur but where its preferred host species, Populus alba, is present. The main environmental variables associated with the distribution of A. sarta at a global level were the average annual temperature and precipitation rate. The predictive models developed in this study offer insights into the global risk of A. sarta establishment and can be valuable for monitoring potential pest introductions in different countries. Additionally, policymakers and trade negotiators can utilize these models to make science-based decisions regarding pest management and international trade agreements.

Genomic investigation of Lactococcus formosensis, Lactococcus garvieae, and Lactococcus petauri reveals differences in species distribution by human and animal sources.

Lactococcus formosensis and Lactococcus petauri are two newly discovered bacteria, which are closely related to Lactococcus garvieae, a pathogen that affects farmed rainbow trout, as well as causes cow mastitis and human infections. It is unclear whether the three bacteria differ in their host preference and the presence of genes that contribute to the development of disease. This study shows that L. formosensis and L. petauri were commonly misidentified as L. garvieae. The three bacteria showed different distribution patterns across various sources. L. petauri was predominantly found in human infections and rainbow trout, while L. formosensis was more commonly detected in cow mastitis. Fifteen genes displayed a differential distribution among the three bacteria from certain sources, indicating a genetic basis for the observed host preference. This work indicates the importance of differentiating the three bacteria in diagnostic laboratories for surveillance and outbreak investigation purposes.

LIFE HISTORY PARAMETERS OF MELON FRUIT FLY, BACTROCERA CUCURBITAE (COQUILLETT) (DIPTERA: TEPHRITIDAE) ON FOUR ECONOMICALLY IMPORTANT VEGETABLES

The majority of plant species that are used for consumption and medicinal purposes belongs to Cucurbitaceae. These vegetables are attacked by several insect pests including Tephritid flies. Keeping in view, four economically important cucurbit vegetables such as sponge gourd; Luffa aegyptiaca, bitter gourd; Momordica charantia, musk melon; Cucumis melo, and bottle gourd; Lagenaria siceraria were selected to investigate the life-history parameters of Bactrocera cucurbitae (Coq.) (Diptera: Tephritidae) under laboratory conditions. For this purpose, B. cucurbitae was reared in the laboratory on each host vegetable and egg hatchability %, egg incubation period, larval survival (%), duration (days), length and width of larvae, pupal parameters, male-female ratio, and age-specific fecundity were recorded. The results showedno statistical difference in hatchability percentages, larval duration, and pupal survival (%) in all tested vegetables. However, greater length and width of larvae were recorded when the B. cucurbitae larvae were provided with bottle gourd. Moreover, maximum pupal recovery was recorded in bottle and sponge gourd among all the tested vegetables. Maximum females were also recorded in bottle gourd. Adult longevity and fecundity were significantly affected by the host. Maximum female longevity (52 days) was recorded when B. cucurbitae were provided with bottle gourd and minimum (41 days) on sponge gourd. Similarly, maximum fecundity (823 eggs) was also recorded when maggots were fed on bottle gourd and the lowest (611 eggs) on a sponge gourd. In conclusion, Bottle gourd is the most preferable and nutritious host among all the tested vegetables and needs effective management strategies for B. cucurbitae. The output of the present studies would be helpful for the development of an effective integrated pest management (IPM) program for B. cucurbitae in a variety of vegetables.

HOST SPECIFICITY, INFECTION DYNAMICS, AND ALLERGENICITY IN Anisakis SPP. INFESTATION: A REVIEW

Fish and seafood are important in providing protein to human diets. However, they are susceptible to contamination by various parasites, such as nematodes, cestodes, and trematodes. Among these, Anisakis spp. and other species of trematodes belonging to the Anisakidae family are commonly identified in fish and shellfish, posing a significant health risk. This contamination poses a substantial risk to public health, particularly with the increasing prevalence of these parasites in marine fish. The globalisation of cuisines, including sushi, is one of the factors causing this development. The risk of Anisakis contamination has increased due to the global popularity of sushi, a form of Japanese food that features raw or undercooked fish. Gastric anisakiasis is the primary infection in humans, caused by the penetration of L3 larvae into the gastric wall. However, the indefinite symptoms associated with anisakiasis make precise identification challenging, complicating efforts to effectively treat this health issue. This study reviewed the host specificity, risk factors, infection mechanisms, and infestation areas of Anisakis spp. Various reputable sources, including Google Scholar, PubMed Central, ScienceDirect, Springer Link, and the Wiley Online Library, were used to explore the diverse host preferences and the impact of environmental changes. The larvae of Anisakis spp. exhibit diverse host preferences and environmental changes like global warming make hosts more vulnerable. Inadvertent exposure to these parasites occurs when individuals consume raw or undercooked fish and seafood. An extremely serious threat is posed by allergic anisakiasis, characterised by severe symptoms such as respiratory arrest, shock, and collapse. Research focusing on bioactive substances capable of blocking or neutralising the excretions and secretions of Anisakis sp. should be encouraged. Metalloproteinases (MMPs) and serine proteases, in particular, show promise for minimising adverse effects and reducing dependency on medication in treating allergic anisakiasis. Further research and intervention techniques are essential if health issues associated with Anisakis exist.

Multivariate data analysis of process parameters affecting the growth and productivity of stable Chinese hamster ovary cell pools expressing SARS-CoV-2 spike protein as vaccine antigen in early process development.

The recent COVID-19 pandemic revealed an urgent need to develop robust cell culture platforms which can react rapidly to respond to this kind of global health issue. Chinese hamster ovary (CHO) stable pools can be a vital alternative to quickly provide gram amounts of recombinant proteins required for early-phase clinical assays. In this study, we analyze early process development data of recombinant trimeric spike protein Cumate-inducible manufacturing platform utilizing CHO stable pool as a preferred production host across three different stirred-tank bioreactor scales (0.75, 1, and 10 L). The impact of cell passage number as an indicator of cell age, methionine sulfoximine (MSX) concentration as a selection pressure, and cell seeding density was investigated using stable pools expressing three variants of concern. Multivariate data analysis with principal component analysis and batch-wise unfolding technique was applied to evaluate the effect of critical process parameters on production variability and a random forest (RF) model was developed to forecast protein production. In order to further improve process understanding, the RF model was analyzed with Shapley value dependency plots so as to determine what ranges of variables were most associated with increased protein production. Increasing longevity, controlling lactate build-up, and altering pH deadband are considered promising approaches to improve overall culture outcomes. The results also demonstrated that these pools are in general stable expressing similar level of spike proteins up to cell passage 11 (~31 cell generations). This enables to expand enough cells required to seed large volume of 200-2000 L bioreactor.

Enzymatic Activity of Soil on the Occurrence of the Endangered Beetle Cheilotoma musciformis (Coleoptera: Chrysomelidae) in Xerothermic Grasslands.

This work attempts to find the reasons for the rather limited range of occurrence of Cheilotoma musciformis in Poland, based on soil properties, which affects both the plant cover and the entomofauna. The aim of the study was to assess the influence of soil enzyme activity on the occurrence of Ch. musciformis in xerothermic grasslands in Southern Poland. The sites inhabited by the beetle were most often extensively grazed by farm animals or had recently been cleared of bushes. The control plots were in wasteland. The soils of most sites with Ch. musciformis were characterized by significantly higher activity of the tested enzymes and higher content of total organic carbon and total nitrogen, as well as lower pHKCl compared to the control sites. The higher enzymatic activity of soils in sites with the beetle than in the control sites may indicate the dependence of the occurrence of this beetle on the presence of patches of extensively grazed xerothermic grasslands. Grazing influences the behavior of preferred host plant species. Therefore, when planning active protection of xerothermic grasslands inhabited by Ch. musciformis, changes in the biochemical properties of the soil and vegetation structure should be taken into account.

Comparative genomic analysis provides insights into the genetic diversity and pathogenicity of the genus Brucella.

Some Brucella spp. are important pathogens. According to the latest prokaryotic taxonomy, the Brucella genus consists of facultative intracellular parasitic Brucella species and extracellular opportunistic or environmental Brucella species. Intracellular Brucella species include classical and nonclassical types, with different species generally exhibiting host preferences. Some classical intracellular Brucella species can cause zoonotic brucellosis, including B. melitensis, B. abortus, B. suis, and B. canis. Extracellular Brucella species comprise opportunistic or environmental species which belonged formerly to the genus Ochrobactrum and thus nowadays renamed as for example Brucella intermedia or Brucella anthropi, which are the most frequent opportunistic human pathogens within the recently expanded genus Brucella. The cause of the diverse phenotypic characteristics of different Brucella species is still unclear. To further investigate the genetic evolutionary characteristics of the Brucella genus and elucidate the relationship between its genomic composition and prediction of phenotypic traits, we collected the genomic data of Brucella from the NCBI Genome database and conducted a comparative genomics study. We found that classical and nonclassical intracellular Brucella species and extracellular Brucella species exhibited differences in phylogenetic relationships, horizontal gene transfer and distribution patterns of mobile genetic elements, virulence factor genes, and antibiotic resistance genes, showing the close relationship between the genetic variations and prediction of phenotypic traits of different Brucella species. Furthermore, we found significant differences in horizontal gene transfer and the distribution patterns of mobile genetic elements, virulence factor genes, and antibiotic resistance genes between the two chromosomes of Brucella, indicating that the two chromosomes had distinct dynamics and plasticity and played different roles in the survival and evolution of Brucella. These findings provide new directions for exploring the genetic evolutionary characteristics of the Brucella genus and could offer new clues to elucidate the factors influencing the phenotypic diversity of the Brucella genus.