Polyandry may mitigate the negative impact of reproductive interference among bumblebees in Japan.

In social hymenopterans, monandry of the queen is an ancestral trait, and polyandry is a derived trait. Polyandry of the queen is the norm in a limited number of lineages, such as honeybees, leaf-cutting ants, Pogonomyrmex ants, and Vespula wasps, which presumably provide fitness advantages for the whole colony. The queen of the introduced bumblebee, Bombus terrestris, is polyandrous in Japan, whereas it is monandrous in native regions. We hypothesize that polyandry can evolve in a process that avoids the negative impacts of reproductive interference caused by interspecific mating and conducted genetic studies of the invasive species B. terrestris and two native subspecies, Bombus hypocrita sapporoensis and Bombus hypocrita hypocrita, in Japan. Our results revealed that although the native queens of B. hypocrita hypocrita allopatric with B. terrestris were strictly monandrous, the native queens of B. hypocrita sapporoensis sympatric with B. terrestris were polyandrous. These results suggested that the queens of native B. hypocrita sapporoensis do not experience negative impacts on interspecific mating from the invasive B. terrestris. We discuss the possibility that reproductive interference is a driving force in selection for multiple mating through an arms race between sympatric species.

Characterization of oral microbiota in 6-8-month-old small breed dogs.

BACKGROUND: Periodontitis is the most common oral disease in dogs, and its progression and severity are influenced by risk factors, such as age and body size. Recent studies have assessed the canine oral microbiota in relation to different stages of periodontitis and niches within the oral cavity. However, knowledge of the bacterial composition at different ages and body sizes, especially in puppies, is limited. This study aimed to characterize the oral microbiota in the healthy gingiva of small breed puppies using next-generation sequencing. Additionally, we assessed the impact of dental care practices and the presence of retained deciduous teeth on the oral microbiota. RESULTS: In this study, plaque samples were collected from the gingival margin of 20 small breed puppies (age, 6.9 ± 0.6 months). The plaque samples were subjected to next-generation sequencing targeting the V3-V4 region of the 16 S rRNA. The microbiota of the plaque samples was composed mostly of gram-negative bacteria, primarily Proteobacteria (54.12%), Bacteroidetes (28.79%), and Fusobacteria (5.11%). Moraxella sp. COT-017, Capnocytophaga cynodegmi COT-254, and Bergeyella zoohelcum COT-186 were abundant in the oral cavity of the puppies. In contrast, Neisseria animaloris were not detected. The high abundance of Pasteurellaceae suggests that this genus is characteristic of the oral microbiota in puppies. Dental care practices and the presence of retained deciduous teeth showed no effects on the oral microbiota. CONCLUSIONS: In this study, many bacterial species previously reported to be detected in the normal oral cavity of adult dogs were also detected in 6-8-month-old small breed dogs. On the other hand, some bacterial species were not detected at all, while others were detected in high abundance. These data indicate that the oral microbiota of 6-8-month-old small breed dogs is in the process of maturating in to the adult microbiota and may also have characteristics of the small dog oral microbiota.

Otoscopy-assisted intranasal cyst marsupialization for congenital dacryocystocele.

We describe 3 infants with congenital dacryocystocele resistant to conservative treatment who were treated with a novel, simple intranasal cyst marsupialization (ICM) technique. Otoscopy-guided ICM was performed by an otolaryngologist in the manner of otoscopic myringotomy for cases with nasal cyst distension. All 3 infants were treated successfully by a single surgical procedure under topical anesthesia in an office setting.

Cervical angle as a possible predictor of abnormal placental position in women with endometriosis.

BACKGROUND: We aimed to examine the effects of endometriosis on the rate of abnormal placentation by comparing the data of pregnant women with and without endometriosis. METHODS: A case-control study was conducted to compare the perinatal outcomes between women with and without endometriosis. In the subgroup analysis, magnetic resonance imaging (MRI) scans of pregnant women with placenta previa were used to measure the cervical angle and its relationship with endometriosis. The cervical angle was measured as the angle between the cervical glands and the line perpendicular to the spinal column in each sagittal MRI section. RESULTS: We retrospectively analyzed data from 3453 cases of singleton deliveries between 2015 and 2019 at two study facilities. Among them, 159 had clinically or surgically confirmed endometriosis. The odds ratio (OR) for abnormal placental position was significantly higher in pregnant women with endometriosis (OR. 2.82; 95% confidence interval [CI], 1.58-5.04). The OR was 3.21 (95% CI, 1.57-6.55) in the endometriosis-surgery group (91 patients) and 2.32 (95% CI, 0.91-5.88) in the non-surgery group (68 patients). Furthermore, 44 women who underwent pelvic MRI after 30 weeks of gestation were included to examine the cervical angle. Then, we compared the date of pregnant women with (n = 6) and without endometriosis (n = 38). Regardless of placental attachment position, the cervical angle was significantly lower in the group with than in the group without a history of endometriosis. CONCLUSION: Pregnant women with a history of endometriosis may have stronger uterine retroversion, which could potentially contribute to abnormal placental positioning.

Association between brain imaging biomarkers and continuous glucose monitoring-derived glycemic control indices in Japanese patients with type 2 diabetes mellitus.

INTRODUCTION: Although type 2 diabetes mellitus (T2DM) is associated with alterations in brain structure, the relationship between glycemic control indices and brain imaging markers remains unclear. This study aimed to investigate the association between continuous glucose monitoring (CGM)-derived glycemic control indices and brain imaging biomarkers assessed by MRI. RESEARCH DESIGN AND METHODS: This cross-sectional study included 150 patients with T2DM. The severity of cerebral white matter lesions (WMLs) was assessed using MRI for deep and subcortical white matter and periventricular hyperintensities. The degree of medial temporal lobe atrophy (MTA) was assessed using voxel-based morphometry. Each participant wore a retrospective CGM for 14 consecutive days, and glycemic control indices, such as time in range (TIR) and glycemia risk index (GRI), were calculated. RESULTS: The proportion of patients with severe WMLs showed a decreasing trend with increasing TIR (P for trend=0.006). The proportion of patients with severe WMLs showed an increasing trend with worsening GRI (P for trend=0.011). In contrast, no significant association was observed between the degree of MTA and CGM-derived glycemic control indices, including TIR (P for trend=0.325) and GRI (P for trend=0.447). CONCLUSIONS: The findings of this study indicate that the severity of WMLs is associated with TIR and GRI, which are indices of the quality of glycemic control. TRIAL REGISTRATION NUMBER: UMIN000032143.

The association between trypsin-like protease activity in the oral cavity and kidney function in Japanese workers.

AIM: To evaluate the association between trypsin-like protease (TLP) activity in the oral cavity as an indicator of periodontal health status and kidney function in Japanese workers. MATERIALS AND METHODS: This cross-sectional study included 1117 Japanese workers (mean age = 43.8 years). Tongue-swab TLP activity was quantified as a* value (the redness intensity of the matrix disc of the TLP activity assessment kit; a larger value indicates more intense enzymatic activity in the samples and poorer periodontal health status). Kidney function was assessed using the estimated glomerular filtration rate (eGFR; a lower value indicates poorer kidney function). We performed ordinal logistic regression analyses to assess the association of the a* value with three eGFR categories: ≥90, 60-89 and <60 mL/min/1.73 m2 . RESULTS: The prevalence for each eGFR category was as follows: ≥90 (31.6%), 60-89 (63.8%) and <60 mL/min/1.73 m2 (4.6%). After adjusting for potential confounders, the a* value was found to be significantly associated with reduced kidney function. The multivariable-adjusted odds ratio (95% confidence interval) for reduced kidney function was 1.12 (1.02-1.22) per unit increase in the a* value. CONCLUSIONS: Higher TLP activity was associated with reduced kidney function in Japanese workers.

Conserved infections and reproductive phenotypes of Wolbachia symbionts in Asian tortrix moths.

Wolbachia is a ubiquitous endosymbiotic bacterium that manipulates insect reproduction. A notable feature of Wolbachia is male killing (MK), whereby sons of infected females are killed during development; however, the evolutionary processes by which Wolbachia acquired the MK ability remain unclear. The tea tortrix moth Homona magnanima (Tortricidae) harbours three non-MK Wolbachia strains (wHm-a, wHm-b and wHm-c) and an MK strain wHm-t. Although wHm-t and wHm-c are closely related, only wHm-t has an MK-associated prophage region. To understand the evolutionary processes underlying the emergence of MK wHm-t, we examined Wolbachia infections and phenotypes in 62 tortricid species collected from 39 localities across Japan, Taiwan, Vietnam and Indonesia. PCR assays detected wHm-c relatives in 51 species and triple infection of wHm-a, wHm-b and wHm-c in 31 species. Apart from Taiwanese H. magnanima, no species exhibited the MK phenotype and were positive for the wHm-t-specific prophage. While wHm-t infection was dominant in Taiwanese H. magnanima, wHm-a, wHm-b and wHm-c were dominant in Japanese H. magnanima populations. These results suggest that wHm-a, wHm-b and wHm-c strains descended from a common ancestor with repeated infection loss and that wHm-t evolved from the wHm-c acquiring MK ability in allopatric populations of H. magnanima.

Association between continuous glucose monitoring-derived glycemic control indices and urinary biomarkers of diabetic kidney disease: Hyogo Diabetes Hypoglycemia Cognition Complications study.

AIMS: Glomerular damage and proximal tubular damage play an important role in the pathogenesis of diabetic kidney disease. This study aimed to investigate the relationship between the urinary markers of proximal tubular injury, including urinary liver-type fatty acid-binding protein-to-creatinine ratio (uL-FABP/Cr) and urinary N-acetyl-ß-D-glucosaminidase-to-creatinine ratio (uNAG/Cr), and glycemic control status. METHODS: This cross-sectional study included 245 and 39 patients with type 2 diabetes mellitus (T2DM) and non-T2DM (NDM), respectively. The participants of this study were fitted with retrospective CGM, and glycemic control indices, such as time in range (TIR) and glycemia risk index (GRI), were calculated. RESULTS: The results were presented as medians (interquartile ranges). The uL-FABP/Cr was significantly higher in the microalbuminuria than in the normo-albuminuria group [4.2 (2.7-7.1) and 2.2 (1.4-3.4) µg/gCr, respectively, P < 0.001], while the uNAG/Cr in the normo-albuminuria group [6.3 (4.5-10.1) U/gCr] was significantly higher than that in the NDM group [5.3 (3.8-6.3) U/gCr, P = 0.048] but significantly lower than that in the microalbuminuria group [9.2 (6.4-11.1) U/gCr, P = 0.004]. The multivariate logistic regression analysis indicated that CGM-derived TIR was significantly associated with the urinary albumin-to-creatinine ratio [uAlb/Cr, odds ratio (OR) 0.985, 95% confidence interval (CI) 0.971-0.998, P = 0.029] and uNAG/Cr (OR 0.973, 95% CI 0.957-0.989, P = 0.001) independent of renal function. GRI was similarly associated with uAlb/Cr and uNAG/Cr. CONCLUSION: The findings of this study indicated that uNAG/Cr was elevated before albuminuria development and was associated with CGM-derived TIR and GRI.

Association between low-carbohydrate diets and continuous glucose monitoring-derived time in ranges.

AIMS: Low-carbohydrate diets have become popular in the general community. The mutual relationship between the percentage of total energy intake from carbohydrates (CHO/E), glycemic control indices, and diabetes complications remains unclear. MATERIALS AND METHODS: This cross-sectional study included 177 patients with type 2 diabetes mellitus who regularly visited outpatient clinics. In this study, dietary questionnaires were used to assess the intake ratio of the three macronutrients, and the low-carbohydrate-diet score was calculated. We investigated the association between the low-carbohydrate-diet score, continuous glucose monitoring (CGM)-derived short-term glycemic control indices, and diabetes complications in patients with type 2 diabetes mellitus. RESULTS: The results are presented as medians (interquartile ranges) unless otherwise stated. Hemoglobin A1c was 7.1% (6.6-7.7%), CGM-derived time in range (TIR) was 75.3% (62.8-87.0%), body mass index (BMI) was 24.0 (22.1-26.3) kg/m2, and CHO/E was 49.8% (44.8-55.6%). BMI, triglycerides, and CGM-derived time above range decreased significantly with increasing low-carbohydrate-diet scores. However, no significant association was found between the low-carbohydrate-diet score and glycemic control indices, including TIR, mean amplitude of glycemic excursions, and vascular complications of type 2 diabetes mellitus. CONCLUSION: Moderate-carbohydrate diets positively impact weight control and lipid metabolism but may have a limited effect on short-term glycemic variability in Japanese patients with type 2 diabetes mellitus.

Combined actions of bacteriophage-encoded genes in Wolbachia-induced male lethality.

Some Wolbachia endosymbionts induce male killing, whereby male offspring of infected females are killed during development; however, the origin and diversity of the underlying mechanisms remain unclear. In this study, we identified a 76 kbp prophage region specific to male-killing Wolbachia hosted by the moth Homona magnanima. The prophage encoded a homolog of the male-killing gene oscar in Ostrinia moths and the wmk gene that induces various toxicities in Drosophila melanogaster. Upon overexpressing these genes in D. melanogaster, wmk-1 and wmk-3 killed all males and most females, whereas Hm-oscar, wmk-2, and wmk-4 had no impact on insect survival. Strikingly, co-expression of tandemly arrayed wmk-3 and wmk-4 killed 90% of males and restored 70% of females, suggesting their conjugated functions for male-specific lethality. While the male-killing gene in the native host remains unknown, our findings highlight the role of bacteriophages in male-killing evolution and differences in male-killing mechanisms among insects.

Diverse Molecular Mechanisms Underlying Microbe-Inducing Male Killing in the Moth Homona magnanima.

Male killing (MK) is a type of reproductive manipulation induced by microbes, where sons of infected mothers are killed during development. MK is a strategy that enhances the fitness of the microbes, and the underlying mechanisms and the process of their evolution have attracted substantial attention. Homona magnanima, a moth, harbors two embryonic MK bacteria, namely, Wolbachia (Alphaproteobacteria) and Spiroplasma (Mollicutes), and a larval MK virus, Osugoroshi virus (OGV; Partitiviridae). However, whether the three distantly related male killers employ similar or different mechanisms to accomplish MK remains unknown. Here, we clarified the differential effects of the three male killers on the sex-determination cascades and development of H. magnanima males. Reverse transcription-PCR demonstrated that Wolbachia and Spiroplasma, but not OGVs, disrupted the sex-determination cascade of males by inducing female-type splice variants of doublesex (dsx), a downstream regulator of the sex-determining gene cascade. We also found that MK microbes altered host transcriptomes in different manners; Wolbachia impaired the host dosage compensation system, whereas Spiroplasma and OGVs did not. Moreover, Wolbachia and Spiroplasma, but not OGVs, triggered abnormal apoptosis in male embryos. These findings suggest that distantly related microbes employ distinct machineries to kill males of the identical host species, which would be the outcome of the convergent evolution. IMPORTANCE Many microbes induce male killing (MK) in various insect species. However, it is not well understood whether microbes adopt similar or different MK mechanisms. This gap in our knowledge is partly because different insect models have been examined for each MK microbe. Here, we compared three taxonomically distinct male killers (i.e., Wolbachia, Spiroplasma, and a partiti-like virus) that infect the same host. We provided evidence that microbes can cause MK through distinct mechanisms that differ in the expression of genes involved in sex determination, dosage compensation, and apoptosis. These results imply independent evolutionary scenarios for the acquisition of their MK ability.

Infection Prevalence of Microsporidia Vairimorpha (Nosema) spp. in Japanese Bumblebees.

Microsporidia are spore-forming intracellular parasites of various invertebrates and vertebrates. Vairimorpha bombi negatively affects the fitness of bumblebees and its prevalence correlates with declining bumblebee populations. The invasive alien species Bombus terrestris colonized Japan and possibly introduced new parasites. To assess the infection prevalence of V. bombi in Japanese bumblebees and B. terrestris, we investigated V. bombi infections using PCR and microscopy. The prevalence of sporulating V. bombi infections in three Bombus s. str. species/subspecies was low, whereas that of non/low-sporulating Vairimorpha sp. infections in three Diversobombus species/subspecies was high. Invasive B. terrestris showed low prevalence of non/low-sporulating V. bombi infections and shared the same V. bombi haplotype with B. hypocrita found in Hokkaido, where B. terrestris is present, and in Honshu, where B. terrestris is absent. Although V. bombi may have been introduced with B. terrestris colonies imported from Europe, it seems to be originally distributed in Japan. Furthermore, a new Vairimorpha sp. was found in Japanese bumblebee species. V. bombi and Vairimorpha sp. showed different organ and host specificities in bumblebees. There are no reports on the specific effects of other Vairimorpha spp. on bumblebees; further studies are needed to clarify the individual characteristics of Vairimorpha spp.

Distinct effects of three Wolbachia strains on fitness and immune traits in Homona magnanima.

The endosymbiotic bacterium Wolbachia occasionally increases host fitness or manipulates host reproductions to enhance vertical transmission. Multiple Wolbachia strains can coinfect the same host individual, which alters the density as well as phenotypes of the bacteria. However, the effects of Wolbachia coinfection on host fitness remain largely unknown. Here, we examined the effects of three phylogenetically distinct Wolbachia strains, wHm-a, wHm-b, and wHm-c, on host fitness by comparing non-infected, singly infected, and triply infected Homona magnanima lines within a fixed genetic background. By examining the effects of Wolbachia on host longevity, survivorship, and reproduction, we demonstrated that single infection with either wHm-b or wHm-c reduced host reproduction, but the triple infection led to the highest intrinsic growth rate. Susceptibility to the natural pathogens such as viruses and fungi was not different among the lines regardless of Wolbachia infection status. Cellular and humoral immunities were not affected by Wolbachia in females, whereas phenoloxidase activity was suppressed in males of all Wolbachia-infected lines, implying that it was a result of the mother's curse hypothesis or a strategy of Wolbachia to increase their horizontal transmission efficiency. Although how the host's genetic diversity affects the Wolbachia fitness effects is yet unknown, our findings indicated that the effects of Wolbachia are deeply influenced by infection status and that Wolbachia could change symbiotic strategy depending on host sex and transmission route.

Male-killing mechanisms vary between Spiroplasma species.

Male-killing, a male-specific death of arthropod hosts during development, is induced by Spiroplasma (Mollicutes) endosymbionts of the Citri-Poulsonii and the Ixodetis groups, which are phylogenetically distant groups. Spiroplasma poulsonii induces male-killing in Drosophila melanogaster (Diptera) using the Spaid toxin that harbors ankyrin repeats, whereas little is known about the origin and mechanisms of male-killing induced by Spiroplasma ixodetis. Here, we analyzed the genome and the biological characteristics of a male-killing S. ixodetis strain sHm in the moth Homona magnanima (Tortricidae, Lepidoptera). Strain sHm harbored a 2.1 Mb chromosome and two potential plasmids encoding Type IV effectors, putatively involved in virulence and host-symbiont interactions. Moreover, sHm did not harbor the spaid gene but harbored 10 ankyrin genes that were homologous to those in other S. ixodetis strains. In contrast to the predominant existence of S. poulsonii in hemolymph, our quantitative PCR assays revealed a systemic distribution of strain sHm in H. magnanima, with particularly high titers in Malpighian tubules but low titers in hemolymph. Furthermore, transinfection assays confirmed that strain sHm can infect cultured cells derived from distantly related insects, namely Aedes albopictus (Diptera) and Bombyx mori (Lepidoptera). These results suggest different origins and characteristics of S. ixodetis- and S. poulsonii-induced male-killing.

In vitro larval rearing method of eusocial bumblebee Bombus terrestris for toxicity test.

Bumblebees are important pollinators of wild and agricultural plants but recently have been declining due to various stressors, such as pesticides and diseases. Because of the haplo-diploid sex determination system in hymenopterans, experiments using micro-colonies (small sub colonies without a queen) to identify risks to bumblebee health are limited as they are only able to produce males. Therefore, an experimental protocol for rearing bumblebee larvae in vitro is needed to better understand effects on worker larvae. Here, we aimed to establish a rearing method for larvae of Bombus terrestris for use in risk assessment assays. To confirm the validity of our rearing method, we tested two insecticides used for tomato cultivation, chlorfenapyr and dinotefuran. Bombus terrestris larvae fed with a high nutrient quantity and quality diet increased growth per day. All chlorfenapyr-exposed individuals died within 10 days at 2000-fold dilution, an application dose used for tomatoes. There were significant differences in adult emergence rate among almost all chlorfenapyr treatments. On the other hand, sublethal dinotefuran-exposure did not affect rates of pupation and adult emergence, growth, or larval and pupal periods. Although larvae were smaller than in the natural colony, this rearing method for B. terrestris larvae proved to be effective at evaluating realistic sub-colonies to pesticide exposures.

Mass-Rearing and Molecular Studies in Tortricidae Pest Insects.

Tortricidae (Lepidoptera), commonly known as tortrix or leafroller moths, comprises many agricultural and forestry pests, which cause serious agricultural losses. To understand the biology of such pest moths, fundamental techniques have been in high demand. Here, methods for mass-rearing, observations, and molecular studies are developed using two tea tortrix, Homona magnanima and Adoxophyes honmai (Lepidoptera: Tortricidae). Insects were mass-reared with sliced artificial diet and maintained by inbreeding for over 100 generations by considering their biological characteristics. Insects have various sex dimorphisms; hence it is difficult to distinguish the sex during the developing stages, which have prevented subsequent assays. The present work highlighted that the sex of tortricids larvae could be determined by observing testes or lactic-acetic orcein staining to visualize the female-specific W chromosome. Moreover, using the sex determination methods, the present study enabled nucleic acid extractions from sex determined embryos and application toward high throughput sequencing. These tips are applicable for other pest insects and will facilitate further morphological and genetic studies.

Pregnancy in hereditary sensory and autonomic neuropathy type V: A case report and literature review.

OBJECTIVE: Hereditary sensory and autonomic neuropathies (HSANs) are a clinical heterogenous group of inherited neuropathies featuring prominent sensory and autonomic involvement. We report on the management of pregnancy and delivery in a woman with HSAN type V (HSAN-V) that is a rare inherited disease characterized by pain insensitivity, and partial anhidrosis. CASE REPORT: A 25-year-old woman with HSAN-V at six weeks of gestation was referred to our hospital. She decided to continue her pregnancy after the genetic counseling. A multidisciplinary team including her decided to undergo cesarean section due to her short stature and the risk of an emergency in normal delivery. She successfully gave birth at 38 weeks of gestation by cesarean section under general anesthesia following an uneventful pregnancy course. CONCLUSION: Cesarean section seems favorable to vaginal delivery in women with HSANs.

Sleep duration and severe periodontitis in middle-aged Japanese workers.

AIM: To evaluate the association between sleep duration and severe periodontitis in Japanese workers. MATERIALS AND METHODS: This cross-sectional study included 1130 workers (mean age 43.0 years) who underwent full-mouth periodontal examinations and health check-ups and completed a self-administered questionnaire that included questions on sleep duration. Logistic regression and a restricted cubic spline model were used to analyse the data. RESULTS: Severe periodontitis was identified in 6.3% of the study population. Those with <5, 5-5.9, 6-6.9, 7-7.9, and ≥8 hr of sleep were 6.7%, 17.4%, 40.3%, 26.3%, and 8.9%, respectively. After adjusting for potential confounders, study participants who slept <5 hr were more likely to have severe periodontitis (adjusted odds ratio = 2.64; 95% confidence interval = 1.06-6.60) than those who slept 7-7.9 hr. The spline model, with a reference value of 399 min (the median sleep duration), showed a non-linear association between sleep duration and severe periodontitis, where an increased prevalence of severe periodontitis was observed only among those with a shorter sleep duration. The prevalence of severe periodontitis did not increase with longer sleep duration. CONCLUSIONS: Short sleep duration was associated with severe periodontitis in this cohort of Japanese adults.

Sc(OTf)3-Catalyzed Iodocyclization/Ritter-Type Amidation of N-Alkoxypropiolamides: A Synthetic Strategy for Isoxazol-3(2H)-ones.

A Sc(OTf)3-catalyzed iodocyclization/Ritter-type amidation of N-alkoxypropiolamides for the synthesis of 4-iodoisoxazol-3(2H)-ones bearing an amide group has been developed. This domino protocol allows the construction of a valuable heterocycle, isoxazol-3(2H)-one, as well as the introduction of two functional groups. The reaction has a broad substrate scope and can be carried out on a large scale. Control experiments suggest that Sc(OTf)3 acts as a dual activator for both the iodocyclization and amidation steps. In addition, the N-alkoxy group in the substrate suppresses some of the side reactions.

Confirmation of Oryctes rhinoceros nudivirus infections in G-haplotype coconut rhinoceros beetles (Oryctes rhinoceros) from Palauan PCR-positive populations.

Coconut rhinoceros beetle (CRB), Oryctes rhinoceros, is a pest of palm trees in the Pacific. Recently, a remarkable degree of palm damage reported in Guam, Hawaii, Papua New Guinea and Solomon Islands has been associated with a particular haplotype (clade I), known as "CRB-G". In the Palau Archipelago, both CRB-G and another haplotype (clade IV) belonging to the CRB-S cluster coexist in the field. In this study, more than 75% of pheromone trap-captured adults of both haplotypes were Oryctes rhinoceros nudivirus (OrNV)-positive by PCR. No significant difference in OrNV prevalence between the haplotypes was detected. In PCR-positive CRB-G tissue specimens from Palau, viral particles were observed by electron microscopy. Hemocoel injection of CRB larvae with crude virus homogenates from these tissues resulted in viral infection and mortality. OrNV isolated from Palauan-sourced CRB was designated as OrNV-Palau1. Both OrNV-Palau1 and OrNV-X2B, a CRB biological control isolate released in the Pacific, were propagated using the FRI-AnCu-35 cell line for production of inoculum. However, the OrNV-Palau1 isolate exhibited lower viral production levels and longer larval survival times compared to OrNV-X2B in O. rhinoceros larvae. Full genome sequences of the OrNV-Palau1 and -X2B isolates were determined and found to be closely related to each other. Altogether these results suggest CRB adults in Palau are infected with a less virulent virus, which may affect the nature and extent of OrNV-induced pathology in Palauan populations of CRB.