Promiscuous feeding on multiple adult honey bee hosts amplifies the vectorial capacity of Varroa destructor.

Varroa destructor is a cosmopolitan pest and leading cause of colony loss of the European honey bee. Historically described as a competent vector of honey bee viruses, this arthropod vector is the cause of a global pandemic of Deformed wing virus, now endemic in honeybee populations in all Varroa-infested regions. Our work shows that viral spread is driven by Varroa actively switching from one adult bee to another as they feed. Assays using fluorescent microspheres were used to indicate the movement of fluids in both directions between host and vector when Varroa feed. Therefore, Varroa could be in either an infectious or naïve state dependent upon the disease status of their host. We tested this and confirmed that the relative risk of a Varroa feeding depended on their previous host's infectiousness. Varroa exhibit remarkable heterogeneity in their host-switching behavior, with some Varroa infrequently switching while others switch at least daily. As a result, relatively few of the most active Varroa parasitize the majority of bees. This multiple-feeding behavior has analogs in vectorial capacity models of other systems, where promiscuous feeding by individual vectors is a leading driver of vectorial capacity. We propose that the honeybee-Varroa relationship offers a unique opportunity to apply principles of vectorial capacity to a social organism, as virus transmission is both vectored and occurs through multiple host-to-host routes common to a crowded society.

Susceptible and infectious states for both vector and host in a dynamic pathogen-vector-host system.

Deformed wing virus (DWV) is a resurgent insect pathogen of honeybees that is efficiently transmitted by vectors and through host social contact. Continual transmission of DWV between hosts and vectors is required to maintain the pathogen within the population, and this vector-host-pathogen system offers unique disease transmission dynamics for pathogen maintenance between vectors and a social host. In a series of experiments, we measured vector-vector, host-host and host-vector transmission routes and show how these maintain DWV in honeybee populations. We found co-infestations on shared hosts allowed for movement of DWV from mite to mite. Additionally, two social behaviours of the honeybee, trophallaxis and cannibalization of pupae, provide routes for horizontal transmission from bee to bee. Circulation of the virus solely among hosts through communicable modes provides a reservoir of DWV for naïve Varroa to acquire and subsequently vector the pathogen. Our findings illustrate the importance of community transmission between hosts and vector transmission. We use these results to highlight the key avenues used by DWV during maintenance and infection and point to similarities with a handful of other infectious diseases of zoonotic and medical importance.

Genome Resequencing Reveals Rapid, Repeated Evolution in the Colorado Potato Beetle.

Insecticide resistance and rapid pest evolution threatens food security and the development of sustainable agricultural practices, yet the evolutionary mechanisms that allow pests to rapidly adapt to control tactics remains unclear. Here, we examine how a global super-pest, the Colorado potato beetle (CPB), Leptinotarsa decemlineata, rapidly evolves resistance to insecticides. Using whole-genome resequencing and transcriptomic data focused on its ancestral and pest range in North America, we assess evidence for three, nonmutually exclusive models of rapid evolution: pervasive selection on novel mutations, rapid regulatory evolution, and repeated selection on standing genetic variation. Population genomic analysis demonstrates that CPB is geographically structured, even among recently established pest populations. Pest populations exhibit similar levels of nucleotide diversity, relative to nonpest populations, and show evidence of recent expansion. Genome scans provide clear signatures of repeated adaptation across CPB populations, with especially strong evidence of selection on insecticide resistance genes in different populations. Analyses of gene expression show that constitutive upregulation of candidate insecticide resistance genes drives distinctive population patterns. CPB evolves insecticide resistance repeatedly across agricultural regions, leveraging similar genetic pathways but different genes, demonstrating a polygenic trait architecture for insecticide resistance that can evolve from standing genetic variation. Despite expectations, we do not find support for strong selection on novel mutations, or rapid evolution from selection on regulatory genes. These results suggest that integrated pest management practices must mitigate the evolution of polygenic resistance phenotypes among local pest populations, in order to maintain the efficacy and sustainability of novel control techniques.

The role of structural variants in pest adaptation and genome evolution of the Colorado potato beetle, Leptinotarsa decemlineata (Say).

Structural variation has been associated with genetic diversity and adaptation. Despite these observations, it is not clear what their relative importance is for evolution, especially in rapidly adapting species. Here, we examine the significance of structural polymorphisms in pesticide resistance evolution of the agricultural super-pest, the Colorado potato beetle, Leptinotarsa decemlineata. By employing a parent offspring trio sequencing procedure, we develop highly contiguous reference genomes to characterize structural variation. These updated assemblies represent >100-fold improvement of contiguity and include derived pest and ancestral nonpest individuals. We identify >200,000 structural variations, which appear to be nonrandomly distributed across the genome as they co-occur with transposable elements and genes. Structural variations intersect with exons in a large proportion of gene annotations (~20%) that are associated with insecticide resistance (including cytochrome P450s), development, and transcription. To understand the role structural variations play in adaptation, we measure their allele frequencies among an additional 57 individuals using whole genome resequencing data, which represents pest and nonpest populations of North America. Incorporating multiple independent tests to detect the signature of natural selection using SNP data, we identify 14 genes that are probably under positive selection, include structural variations, and SNPs of elevated frequency within the pest lineages. Among these, three are associated with insecticide resistance based on previous research. One of these genes, CYP4g15, is coinduced during insecticide exposure with glycosyltransferase-13, which is a duplicated gene enclosed within a structural variant adjacent to the CYP4g15 genic region. These results demonstrate the significance of structural variations as a genomic feature to describe species history, genetic diversity, and adaptation.

Arsenophonus apicola sp. nov., isolated from the honeybee Apis mellifera.

The genus Arsenophonus has been traditionally considered to comprise heritable bacterial symbionts of arthropods. Recent work has reported a microbe related to the type species Arsenophonus nasoniae as infecting the honey bee, Apis mellifera. The association was unusual for members of the genus in that the microbe-host interaction arose through environmental and social exposure rather than vertical transmission. In this study, we describe the in vitro culture of ArsBeeUST, a strain of this microbe isolated from A. mellifera in the USA. The 16S rRNA sequence of the isolated strain indicates it falls within the genus Arsenophonus. Biolog analysis indicates the bacterium has a restricted range of nutrients that support growth. In vivo experiments demonstrate the strain proliferates rapidly on injection into A. mellifera hosts. We further report the closed genome sequence for the strain. The genome is 3.3 Mb and the G+C content is 37.6 mol%, which is smaller than A. nasoniae but larger than the genomes reported for non-culturable Arsenophonus symbionts. The genome is complex, with six extrachromosomal elements and 11 predicted intact phage elements, but notably less complex than A. nasoniae. Strain ArsBeeUST is clearly distinct from the type species A. nasoniae on the basis of genome sequence, with 92 % average nucleotide identity. Based on our results, we propose Arsenophonus apicola sp. nov., with the type strain ArsBeeUST (CECT 30499T=DSM113403T=LMG 32504T).

Elevated rates of positive selection drive the evolution of pestiferousness in the Colorado potato beetle (Leptinotarsa decemlineata, Say).

Contextualizing evolutionary history and identifying genomic features of an insect that might contribute to its pest status is important in developing early detection and control tactics. In order to understand the evolution of pestiferousness, which we define as the accumulation of traits that contribute to an insect population's success in an agroecosystem, we tested the importance of known genomic properties associated with rapid adaptation in the Colorado potato beetle (CPB), Leptinotarsa decemlineata Say. Within the leaf beetle genus Leptinotarsa, only CPB, and a few populations therein, has risen to pest status on cultivated nightshades, Solanum. Using whole genomes from ten closely related Leptinotarsa species native to the United States, we reconstructed a high-quality species tree and used this phylogenetic framework to assess evolutionary patterns in four genomic features of rapid adaptation: standing genetic variation, gene family expansion and contraction, transposable element abundance and location, and positive selection at protein-coding genes. Throughout approximately 20 million years of history, Leptinotarsa species show little evidence of gene family turnover and transposable element variation. However, there is a clear pattern of CPB experiencing higher rates of positive selection on protein-coding genes. We determine that these rates are associated with greater standing genetic variation due to larger effective population size, which supports the theory that the demographic history contributes to rates of protein evolution. Furthermore, we identify a suite of coding genes under positive selection that are putatively associated with pestiferousness in the Colorado potato beetle lineage. They are involved in the biological processes of xenobiotic detoxification, chemosensation and hormone function.

A daily diary study of minority stress and negative and positive affect among racially diverse sexual minority adolescents.

We conducted an intensive longitudinal study of sexual minority adolescents to address gaps in the literature, limitations in retrospective reporting, and test tenets of the minority stress model. We examined the frequency of daily minority stressors and their within-person associations with negative and positive affect. We also tested the moderating effects of depressive symptomology on these associations. Sexual minority adolescents (N = 94; 35.1% were bisexual; 31.9% were gender minority; 45.2% were racial/ethnic minority), ages 12-18 years old (M = 16.1, SD = 1.5), were recruited from the community and completed a baseline questionnaire and then a 21-day daily dairy (82.5% response rate). Participants experienced at least one minority stressor, with an average of 16.96 minority stressors (SD = 18.7, Range: 0-83), over the 21-day monitoring period. Some minority stressors were more commonly experienced than others (e.g., vicarious minority stress) and most participants attributed their sexual orientation to these stressors. Participants also attributed other marginalized identities to these stressors (e.g., gender identity, race). Daily minority stressors were associated with greater negative affect but not positive affect. Participants had greater negative affect on days where sexual-orientation-specific minority stressors were endorsed compared to days where minority stressors were not reported. These associations were not moderated by depression symptomology. The results underscore that minority stressors are pervasive experiences of sexual minority adolescents' daily life and natural environment and they are associated with daily emotions. The findings have implications for the minority stress model and future research and interventions. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Sexual orientation disparities in mental health and substance use among Black American young people in the USA: effects of cyber and bias-based victimisation.

Few studies have explored sexual orientation disparities in mental health and substance use outcomes among racial minorities. This study examined sexual orientation disparities in depression, suicidality and substance use among Black American young people in the USA, and the mediating role of cyber and bias-based victimisation in accounting for these disparities. Secondary analyses were performed on data from a probability sample of young people (N = 1,129) collected in a school district in the south-eastern USA. Participants reported socio-demographics, depressive symptoms, suicidality, substance use and experiences of bias-based and cyber victimisation. With some exceptions, Black participants who were lesbian, gay, bisexual or mostly heterosexual reported higher rates of depression, suicidal ideation, suicide planning and substance use than Black heterosexual participants. Black lesbian, gay, bisexual and mostly heterosexual participants reported more cyber and bias-based victimisation than Black heterosexual participants. Sexual orientation disparities in mental health and, to some extent, substance use were partially explained by both forms of victimisation. Further research is needed to address the role of bias-based and cyber victimisation in disparities in mental health and substance use among Black sexual minority young people. The present study carries implications for prevention and treatment efforts for racially diverse sexual minorities.

Examining developmental assets of young Black sexual gender minority males in preventing suicidal behaviors.

Black gay and bisexual male adolescents and young adults (BGBMA/YA) are at higher risk for suicidal outcomes given their minoritized and stigmatized identities at the intersection of race and sexual orientation. This study explores key developmental assets, including family support and family communication, and their role in preventing depression symptoms and suicidal outcomes among BGBMA/YA. A cross-sectional survey was administered to participants (N = 400, Mage = 23.46, SD = 2.59) recruited through Amazon M-Turk, community-based organizations, and social media sites. A path analysis was conducted to examine associations among external assets (family support, communication about sex and drugs with parents, open family communication), depression symptoms, and suicidal attempts and plan to die by suicide. About 28 % of respondents reported a suicide attempt in the past 12 months. Depression symptoms and communication about sex and drugs with parents were positively associated with plan to die by suicide. Family support was negatively associated with depression symptoms. Depression symptoms were positively associated with suicide attempts. Family support was indirectly and negatively associated with suicide attempts. Suggestions for future research and policy implications are discussed.

Pre-Exposure Prophylaxis Interventions among Black Sexual Minority Men: A Systematic Literature Review.

BACKGROUND: Interventions to promote HIV pre-exposure prophylaxis (PrEP) among Black sexual minority men (BSMM) are especially important, given the disproportionate HIV incidence and relatively low uptake of PrEP among BSMM. METHODS: We conducted a systematic literature review to identify the characteristics of interventions between 2016 and 2021 promoting PrEP use among BSMM. We synthesized these studies based on sample size, location, the use of peer-based delivery, and key intervention targets. RESULTS: Of the starting total 198 articles, 10 were included in the final review, with the majority of included studies being randomized controlled trials. We identified providing PrEP access, PrEP counseling, HIV and PrEP education, linkage to general health care, and peer-based support as key successful intervention components. The starkest difference between interventions with and without demonstrated PrEP improvements was the outcome: all interventions focused on PrEP initiation led to large improvements, but those focused on PrEP adherence did not. No other factors demonstrated distinct differences between successful and unsuccessful interventions. CONCLUSION: We identified notable differences in intervention efficacy between PrEP initiation and PrEP adherence outcomes; PrEP adherence is necessary for optimal HIV prevention. Future interventions promoting and measuring PrEP adherence, with a focus on cultural competence and peer components, are recommended.

Sexual Risk Behavior and Lifetime HIV Testing: The Role of Adverse Childhood Experiences.

Despite the success of HIV prevention drugs such as PrEP, HIV incident transmission rates remain a significant problem in the United States. A life-course perspective, including experiences of childhood adversity, may be useful in addressing the HIV epidemic. This paper used 2019 BRFSS data to elucidate the role that childhood adversity plays in the relationship between HIV risk and HIV testing. Participants (n = 58,258) completed self-report measures of HIV risk behaviors, HIV testing, and adverse childhood experiences (ACEs). The median number ACEs in the sample was 1, with verbal abuse (33.9%), and parental separation (31.3%) being the most common ACEs reported. Bivariate findings showed that all ACEs were associated with increased HIV risk and testing. However, increased risk was not correlated with increased HIV testing, with the highest incongruence related to mental health problems of household member (53.48%). While both self-reported HIV risk and ACEs were positively associated with HIV testing, their interaction had a negative association with testing (aPR = 0.51, 95%CI 0.42, 0.62). The results highlight the need for targeted HIV prevention strategies for at-risk individuals with a history of childhood adversity.

Pupal cannibalism by worker honey bees contributes to the spread of deformed wing virus.

Transmission routes impact pathogen virulence and genetics, therefore comprehensive knowledge of these routes and their contribution to pathogen circulation is essential for understanding host-pathogen interactions and designing control strategies. Deformed wing virus (DWV), a principal viral pathogen of honey bees associated with increased honey bee mortality and colony losses, became highly virulent with the spread of its vector, the ectoparasitic mite Varroa destructor. Reproduction of Varroa mites occurs in capped brood cells and mite-infested pupae from these cells usually have high levels of DWV. The removal of mite-infested pupae by worker bees, Varroa Sensitive Hygiene (VSH), leads to cannibalization of pupae with high DWV loads, thereby offering an alternative route for virus transmission. We used genetically tagged DWV to investigate virus transmission to and between worker bees following pupal cannibalisation under experimental conditions. We demonstrated that cannibalization of DWV-infected pupae resulted in high levels of this virus in worker bees and that the acquired virus was then transmitted between bees via trophallaxis, allowing circulation of Varroa-vectored DWV variants without the mites. Despite the known benefits of hygienic behaviour, it is possible that higher levels of VSH activity may result in increased transmission of DWV via cannibalism and trophallaxis.

Regional differences in gene regulation may underlie patterns of sensitivity to novel insecticides in Leptinotarsa decemlineata.

BACKGROUND: Agricultural insect pests frequently exhibit geographic variation in levels of insecticide resistance, which are often presumed to be due to the intensity of insecticide use for pest management. However, regional differences in the evolution of resistance to novel insecticides suggests that other factors are influencing rates of adaptation. We examined median lethal concentration (LC50 ) bioassay data spanning 15 years and six insecticides (abamectin, imidacloprid, spinosad, cyantraniliprole, chlorantraniliprole, and metaflumizone) for evidence of regional differences in Leptinotarsa decemlineata baseline sensitivity to insecticides as they became commercially available. RESULTS: We consistently found that larvae from Colorado potato beetle populations from the northwestern USA had the highest baseline sensitivity to novel insecticides, while populations from the eastern USA had the lowest. Comparisons of gene expression between populations from these regions revealed constitutively elevated expression of an array of detoxification genes in the East, but no evidence of additional induction when exposed to imidacloprid. CONCLUSIONS: Our results suggest a mechanism for geographic variation in rates of adaptation to insecticides, whereby baseline levels of gene expression determine a population's response to novel insecticides. These findings have implications for the regional development of insecticide resistance management strategies and for the fundamental question of what determines the rate of adaptation to insecticides. © 2020 Society of Chemical Industry.

Phylogeography of a specialist insect, Adelges cooleyi: historical and contemporary processes shape the distribution of population genetic variation.

Adelges cooleyi is a host-alternating, gall-making insect native to the Rocky Mountains and Cascade Mountains in western North America. The insect's primary hosts are Picea (spruce) species, and its secondary host is Pseudotsuga menziesii, Douglas fir. To determine whether there are large-scale patterns of genetic variation in this specialist insect, we created molecular phylogenies of geographically separate samples of A. cooleyi using sequence data from two mitochondrial (mtDNA) genes and amplified fragment length polymorphisms (AFLPs). Three divergent mtDNA lineages were identified. Analysis of mtDNA and AFLP genetic variation revealed that samples from southeastern Arizona are genetically isolated from all other samples. AFLP data identified possible gene flow between individuals from divergent mtDNA lineages in an area in the central Rocky Mountains. Factors that likely affected divergence within A. cooleyi were identified by comparing our conclusions with well-known changes in the distribution of vegetation in response to glaciations and previous phylogeographical work conducted on this specialist insect's host-plants. In addition to documenting previously unknown patterns of genetic variation in A. cooleyi, our work provides the basis for a testable hypothesis regarding the extent to which the distribution of variation in Picea and Pseudotsuga hosts mediates the distribution of genetic variation for this specialist insect.

Integrating Health and Community Development for Health Equity: Philanthropic Investments in Baltimore City, 2010-2017.

Purpose: Achieving health equity requires addressing the social determinants of health, which philanthropy has supported through community development grants. This study analyzes health topics that have been integrated into community development grants. Methods: Community development grants from 2010 to 2017 were analyzed for health topics in Baltimore, MD. Results: Food and nutrition, chronic disease, reproductive health, adolescent health, violence prevention, health care access, and infectious disease were the least common health topics in community development grants. Conclusion: To support health equity efforts, funders should consider a broader range of health issues to integrate into community development investments.

Origin of Pest Lineages of the Colorado Potato Beetle (Coleoptera: Chrysomelidae).

Colorado potato beetle (Leptinotarsa decemlineata Say [Coleoptera: Chrysomelidae]) is a pest of potato throughout the Northern Hemisphere, but little is known about the beetle's origins as a pest. We sampled the beetle from uncultivated Solanum host plants in Mexico, and from pest and non-pest populations in the United States and used mitochondrial DNA and nuclear loci to examine three hypotheses on the origin of the pest lineages: 1) the pest beetles originated from Mexican populations, 2) they descended from hybridization between previously divergent populations, or 3) they descended from populations that are native to the Plains states in the United States. Mitochondrial haplotypes of non-pest populations from Mexico and Arizona differed substantially from beetles collected from the southern plains and potato fields in the United States, indicating that beetles from Mexico and Arizona did not contribute to founding the pest lineages. Similar results were observed for AFLP and microsatellite data . In contrast, non-pest populations from the states of Colorado, Kansas, Nebraska, New Mexico, and Texas were genetically similar to U.S. pest populations, indicating that they contributed to the founding of the pest lineages. Most of the pest populations do not show a significant reduction in genetic diversity compared to the plains populations in the United States. We conclude that genetically heterogeneous beetle populations expanded onto potato from native Solanum hosts. This mode of host range expansion may have contributed to the abundant genetic diversity of contemporary populations, perhaps contributing to the rapid evolution of climate tolerance, host range, and insecticide resistance.

Correction: Assessment of Chronic Sublethal Effects of Imidacloprid on Honey Bee Colony Health.

[This corrects the article DOI: 10.1371/journal.pone.0118748.].

Implicating ABC Transporters in Insecticide Resistance: Research Strategies and a Decision Framework.

Pest insects damage crops, transmit diseases, and are household nuisances. Historically, they have been controlled with insecticides, but overuse often leads to resistance to one or more of these chemicals. Insects gain resistance to insecticides through behavioral, metabolic, genetic, and physical mechanisms. One frequently overlooked strategy is through the use of ATP-binding cassette (ABC) transporters. ABC transporters, present in all domains of life, perform natural excretory functions, thus the exploitation of these transporters to excrete insecticides and contribute to resistance is highly plausible. Previous work has implicated ABC transporters in some cases of insecticide resistance. Proposed herein is a framework meant as a formal guide for more easily incorporating the analysis of ABC transporters into existing resistance monitoring using suggested simple research methods. This framework functions as a simple decision tree and its utility is demonstrated using case examples. Determining a role for ABC transporters in insecticide resistance would help to shape future resistance management plans and guide the design of new insecticides.

Evidence for ecological speciation via a host shift in the holly leaf miner, Phytomyza glabricola (Diptera: Agromyzidae).

Evolutionary radiations have been well documented in plants and insects, and natural selection may often underly these radiations. If radiations are adaptive, the diversity of species could be due to ecological speciation in these lineages. Agromyzid flies exhibit patterns of repeated host-associated radiations. We investigated whether host-associated population divergence and evidence of divergent selection exist in the leaf miner Phytomyza glabricola on its sympatric host plants, the holly species, Ilex coriacea and I. glabra. Using AFLPs and nuclear sequence data, we found substantial genetic divergence between host-associated populations of these flies throughout their geographic range. Genome scans using the AFLP data identified 13 loci under divergent selection, consistent with processes of ecological speciation. EF-1α data suggest that I. glabra is the original host of P. glabricola and that I. coriacea is the novel host, but the AFLP data are ambiguous with regard to directionality of the host shift.

Multi-Drug Resistance Transporters and a Mechanism-Based Strategy for Assessing Risks of Pesticide Combinations to Honey Bees.

Annual losses of honey bee colonies remain high and pesticide exposure is one possible cause. Dangerous combinations of pesticides, plant-produced compounds and antibiotics added to hives may cause or contribute to losses, but it is very difficult to test the many combinations of those compounds that bees encounter. We propose a mechanism-based strategy for simplifying the assessment of combinations of compounds, focusing here on compounds that interact with xenobiotic handling ABC transporters. We evaluate the use of ivermectin as a model substrate for these transporters. Compounds that increase sensitivity of bees to ivermectin may be inhibiting key transporters. We show that several compounds commonly encountered by honey bees (fumagillin, Pristine, quercetin) significantly increased honey bee mortality due to ivermectin and significantly reduced the LC50 of ivermectin suggesting that they may interfere with transporter function. These inhibitors also significantly increased honey bees sensitivity to the neonicotinoid insecticide acetamiprid. This mechanism-based strategy may dramatically reduce the number of tests needed to assess the possibility of adverse combinations among pesticides. We also demonstrate an in vivo transporter assay that provides physical evidence of transporter inhibition by tracking the dynamics of a fluorescent substrate of these transporters (Rhodamine B) in bee tissues. Significantly more Rhodamine B remains in the head and hemolymph of bees pretreated with higher concentrations of the transporter inhibitor verapamil. Mechanism-based strategies for simplifying the assessment of adverse chemical interactions such as described here could improve our ability to identify those combinations that pose significantly greater risk to bees and perhaps improve the risk assessment protocols for honey bees and similar sensitive species.