Outpatient-Based Opioid Treatment Engagement and Attendance: A Prospective Cohort Study of Homeless-Experienced Adults.

BACKGROUND: The opioid overdose epidemic disproportionately impacts people experiencing homelessness. Outpatient-based opioid treatment (OBOT) programs have been established in homeless health care settings across the USA, but little is known about the success of these programs in engaging and retaining this highly marginalized patient population in addiction care. OBJECTIVE: To evaluate predictors of initial engagement and subsequent attendance in a homeless-tailored OBOT program. DESIGN: Prospective cohort study with 4 months of follow-up. PARTICIPANTS: A total of 148 homeless-experienced adults (≥18 years) who newly enrolled in the Boston Healthcare for the Homeless Program (BHCHP) OBOT program over a 1-year period (1/6/2022-1/5/2023). MAIN MEASURES: The primary outcomes were (1) initial OBOT program engagement, defined as having ≥2 additional OBOT visits within 1 month of OBOT enrollment, and (2) subsequent OBOT program attendance, measured monthly from months 2 to 4 of follow-up. KEY RESULTS: The average age was 41.7 years (SD 10.2); 23.6% were female, 35.8% were Hispanic, 12.8% were non-Hispanic Black, and 43.9% were non-Hispanic White. Over one-half (57.4%) were initially engaged. OBOT program attendances during months 2, 3, and 4 were 60.8%, 50.0%, and 41.2%, respectively. One-quarter (24.3%) were initially engaged and then attended the OBOT program every month during the follow-up period. Participants in housing or residential treatment programs (vs. unhoused; adjusted odds ratios (aORs) = 2.52; 95% CI = 1.17-5.44) and those who were already on or initiated a medication for opioid use disorder (OUD) (aOR = 6.53; 95% CI = 1.62-26.25) at the time of OBOT enrollment had higher odds of engagement. Older age (aOR = 1.74 per 10-year increment; 95% CI = 1.28-2.38) and initial engagement (aOR = 3.50; 95% CI = 1.86-6.59) conferred higher odds of attendance. CONCLUSIONS: In this study, over half initially engaged with the OBOT program, with initial engagement emerging as a strong predictor of subsequent OBOT program attendance. Interventions aimed at enhancing initial OBOT program engagement, including those focused on housing and buprenorphine initiation, may improve longer-term outcomes in this marginalized population.

Patient Navigation for Lung Cancer Screening at a Health Care for the Homeless Program: A Randomized Clinical Trial.

Importance: People experiencing homelessness die of lung cancer at rates more than double those in the general population. Lung cancer screening (LCS) with low-dose computed tomography (LDCT) reduces lung cancer mortality, but the circumstances of homelessness create barriers to LCS participation. Objective: To determine whether patient navigation, added to usual care, improved LCS LDCT receipt at a large Health Care for the Homeless (HCH) program. Design, Setting, and Participants: This parallel group, pragmatic, mixed-methods randomized clinical trial was conducted at Boston Health Care for the Homeless Program (BHCHP), a federally qualified HCH program that provides tailored, multidisciplinary care to nearly 10 000 homeless-experienced patients annually. Eligible individuals had a lifetime history of homelessness, had a BHCHP primary care practitioner (PCP), were proficient in English, and met the pre-2022 Medicare coverage criteria for LCS (aged 55-77 years, ≥30 pack-year history of smoking, and smoking within the past 15 years). The study was conducted between November 20, 2020, and March 29, 2023. Intervention: Participants were randomized 2:1 to usual BHCHP care either with or without patient navigation. Following a theory-based, patient-centered protocol, the navigator provided lung cancer education, facilitated LCS shared decision-making visits with PCPs, assisted participants in making and attending LCS LDCT appointments, arranged follow-up when needed, and offered tobacco cessation support for current smokers. Main Outcomes and Measures: The primary outcome was receipt of a 1-time LCS LDCT within 6 months after randomization, with between-group differences assessed by χ2 analysis. Qualitative interviews assessed the perceptions of participants and PCPs about the navigation intervention. Results: In all, 260 participants (mean [SD] age, 60.5 [4.7] years; 184 males [70.8%]; 96 non-Hispanic Black participants [36.9%] and 96 non-Hispanic White participants [36.9%]) were randomly assigned to usual care with (n = 173) or without (n = 87) patient navigation. At 6 months after randomization, 75 participants in the patient navigation arm (43.4%) and 8 of those in the usual care-only arm (9.2%) had completed LCS LDCT (P < .001), representing a 4.7-fold difference. Interviews with participants in the patient navigation arm and PCPs identified key elements of the intervention: multidimensional social support provision, care coordination activities, and interpersonal skills of the navigator. Conclusions and Relevance: In this randomized clinical trial, patient navigation support produced a 4.7-fold increase in 1-time LCS LDCT completion among HCH patients in Boston. Future work should focus on longer-term screening participation and outcomes. Trial Registration: ClinicalTrials.gov Identifier: NCT04308226.

"I'm on the Right Path": Exploring 1-Month Retention in a Homeless-Tailored Outpatient-Based Opioid Treatment Program.

BACKGROUND: Homeless-tailored office-based opioid treatment (OBOT) programs have been developed to address the ongoing opioid overdose crisis, which disproportionately affects people experiencing homelessness. The objective of this study was to evaluate the facilitators of and barriers to retention in a homeless-tailored OBOT program. METHODS: We performed in-depth qualitative interviews with 24 homeless-experienced adults who newly enrolled in Boston Health Care for the Homeless Program's OBOT program from January 6, 2022 through January 5, 2023. We purposively sampled participants based on whether they were retained at 1 month (n = 12) or not (n = 12). We used an abductive analytic process, applying codes to the interview transcripts from an a priori analytic framework based on the Behavioral Model for Vulnerable Populations and supplementing with emergent codes as needed. We compared themes by participants' 1-month retention status to explore facilitators of and barriers to retention in OBOT care. RESULTS: The average age was 41.9 years, 29.2% were female, 20.8% were Black, 58.3% were White, and 33.0% were Hispanic. Facilitators of retention common to many participants included the clinic experience, low-threshold model, clinic staff, and provision of comprehensive care. Among participants who were retained at 1-month, personal motivation, use of extended-release buprenorphine, and adequate buprenorphine efficacy were additional facilitators. Barriers to retention common to many participants included the clinic's surrounding environment, competing subsistence difficulties, and transportation difficulty. Among participants who were not retained at 1-month, opioid use severity, drug use in social networks, and inadequate buprenorphine efficacy represented additional barriers. CONCLUSIONS: We identified several common determinants of OBOT retention among our homeless-experienced participants as well as some facilitators and barriers that differed by 1-month retention status. These divergent factors represent potential points of intervention to promote retention in homeless-tailored OBOT programs.

Temperature Influence on Aedes aegypti Oviposition in the San Joaquin Valley of California.

The establishment and oviposition of Aedes aegypti can vary from one location to another partially due to differing temperature and precipitation. In 2017, Ae. aegypti was first detected in Merced in the Central Valley of California. The objectives of this study were to examine the influence of temperature and precipitation on oviposition of Ae. aegypti, and to determine the beginning and end of the seasonal activity of Ae. aegypti in Merced. The study site consisted of a residential area in the north-east region of Merced where Ae. aegypti was first detected in Merced County. Fifty-four residences were randomly selected as ovitrap sites. Ovitraps were placed at field sites weekly for 12 months, from September 27, 2017, to September 27, 2018. Each week, ovitraps were inspected for the presence of mosquito eggs. Egg counts were used to calculate the following oviposition indices: the ovitrap index (OI) (percent of traps positive) and the egg density index (EDI) (eggs/positive traps). Oviposition occurred primarily from May through October, above a minimum temperature of 10°C, and when almost no rainfall occurred (0.5 mm total). During the year, the percent of positive traps per month ranged from approximately 1.2-67.3%, with highest values in June to October (43.9-67.3%). The highest mean monthly EDI was from July to October (34-44.6) and peaked in October at 44.6 eggs/trap. The EDI values are similar to other locations where Ae. aegypti transmits endemic vector-borne disease. These findings provide baseline data for Ae. aegypti control in Merced and the Central Valley of California.

Population genetics of Leptoglossus clypealis (Hemiptera: Coreidae) in the Western United States.

The leaffooted bug, Leptoglossus clypealis Heidemann, is a seed-feeding economic pest of crops including almonds and pistachios. The historical distribution of L. clypealis has been considered to be West of the Mississippi in the United States. L. clypealis was recently found in sorghum in the Coastal Bend of Texas, representing a new host record and new collection locality. This study investigated the genetic diversity of L. clypealis museum voucher samples from the Western United States (i.e., Texas, California, and Idaho) collected from 1994 to 2019, including the L. clypealis samples from the Coastal Bend. Eleven new sequences were obtained. Sample sequences were compared with public sequences of L. clypealis from the Western United States. The mitochondrial DNA cytochrome oxidase 1 (mtDNA COI) barcode gene region revealed differences among and within the collection regions. Texas, Idaho, and California all had samples with unique genotypes, and the combined dataset had a haplotype diversity of 1.0. The Texas specimens recently collected in the Coastal Bend did not match genotypes from California or Idaho, and it is unlikely they were recently introduced. Overall, L. clypealis from Texas, Idaho, and California have a high level of genetic diversity, and the 3 regions appear to be within the native range of the species.

Exploring the experience of a cognitive rehabilitation intervention for cancer-related cognitive change in people living with cancer: An interpretative phenomenological analysis.

OBJECTIVES: Some cancer patients experience cancer-related cognitive change (CRCC). Cognitive rehabilitation interventions (CRIs) have recently been developed to help mitigate the impact of CRCC, which, untreated, can impact resumption of daily life post-cancer treatment. The experience of participants is important to understand but largely absent within research literature. This study aimed to explore how those with CRCC experience the phenomenon following completion of a CRI. METHODS: This study comprised a qualitative phenomenological approach. This involved conducting in-depth, semi-structured interviews with 6 self-referred participants from one CRI. Participants were invited to discuss their experience of CRCC and what the CRI therefore meant to them. Interviews were analyzed using interpretative phenomenological analysis. RESULTS: Analysis of the findings revealed 4 key themes. (1) "Experiencing and addressing isolation" comprises reflections on posttreatment perceived abandonment and consequent feelings of belonging through CRI participation. (2) "Identity" explores participants' reflections around perceived loss-of-self and feelings of empowerment from the intervention. (3) "Cognitive and physical balance" comprises the planning and choices participants make, supported by both their own and CRI coping strategies as they seek acceptance of cognitive change. (4) "Course reflections" explore reflections on intervention structure, format, and delivery, focusing on 2 subthemes of accessibility, flexibility and inclusivity, and communication. All participants reflected positively on their experience. SIGNIFICANCE OF RESULTS: Results support further dissemination among health professionals and implementation of this CRI to better support self-reported CRCC concerns within this population. Future qualitative research should explore the long-term impact of CRI interventions.

Health Care Utilization among Homeless-Experienced Adults Who Were Seen by a Mobile Addiction Health Clinic in Boston, Massachusetts: A Quasi-Experimental Study.

Background: Mobile health clinics improve access to care for marginalized individuals who are disengaged from the healthcare system. This study evaluated the association between a mobile addiction health clinic and health care utilization among people experiencing homelessness. Methods: Using Medicaid claims data, we evaluated adults who were seen by a mobile addiction health clinic in Boston, Massachusetts from 1/16/18-1/15/19 relative to a propensity score matched control cohort. We evaluated both cohorts from four years before to one year after the index visit date with the mobile clinic. The primary outcome was the number of outpatient visits; secondary outcomes were the number of hospitalizations and emergency department (ED) visits. We used Poisson regression to compare changes in outcomes from before to after the index date in a quasi-experimental design. Results: 138 adults were seen by the mobile clinic during the observation period; 29.7% were female, 16.7% were Black, 8.0% Hispanic, 68.1% White, and the mean age was 40.4 years. The mean number of mobile clinic encounters was 3.1. The yearly mean number of outpatient visits increased from 11.5 to 12.1 (p = 0.43; pdiff-in-diff = 0.15), the number of hospitalizations increased from 2.2 to 3.0 (p = 0.04; pdiff-in-diff = 0.87), and the number of ED visits increased from 5.4 to 6.5 (p = 0.04; pdiff-in-diff = 0.40). Conclusions: The mobile addiction health clinic was not associated with statistically significant changes in health care utilization in the first year. Further research in larger samples using a broader set of outcomes is needed to quantify the benefits of this innovative care delivery model.

Distribution of Two Strains of Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae) in the Western Hemisphere: Is L. zonatus a Potential Invasive Species in California?

The leaffooted plant bug, Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae) is polyphagous and widely distributed in the Western Hemisphere. Although it has been recorded in California since around 1900, it has become a more common pest in almonds in the last decade. Other studies have shown that an established insect can become a pest when a new genotype is introduced. This study investigated the distribution of two lineages (strains) of L. zonatus in the Western Hemisphere. Specimens from the Leptoglossus collection in the national insect collection in Mexico were used to extract DNA and sequence the mitochondrial DNA cytochrome oxidase I (mtDNA COI) gene, for use in population genetic and phylogenetic analyses. New sequences from Mexico, Central and South America were combined with those available in GenBank, from California and Brazil. Two lineages (strains) of L. zonatus were uncovered. One lineage occurs in California, Mexico and Ecuador. The second lineage is more widespread and found in California, Mexico, Guatemala, Nicaragua, Bolivia and Brazil. The haplotype number and diversity, and nucleotide diversity, were found for samples from California, Mexico, and Brazil, for the two lineages, and for all 118 sequences combined. All sequences combined produced five haplotypes, and a haplotype diversity of 0.54. California and Brazil had 3 haplotypes each, with one haplotype shared (5 total). Haplotype diversity in California and in Brazil were 0.526 and 0.505, respectively. A haplotype network found that one haplotype was most abundant and widespread. The small number of haplotypes, a range expansion, and economic pest status of L. zonatus in California, all contribute to this insect being a potentially invasive insect pest.

Forest Coverage and Socioeconomic Factors Associated with Dengue in El Salvador, 2011-2013.

Dengue virus serotypes 1, 2, 3, and 4 are transmitted by Aedes aegypti and Aedes albopictus mosquitoes, which cause illness in an estimated 100 million annually. Although dengue viruses are endemic throughout El Salvador, very little is known about their ecology and epidemiology. The principal methods to prevent and reduce dengue cases are through vector control and by adoption of a vaccine. In addition, understanding the environmental and socioeconomic factors associated with dengue could contribute to case reduction by targeting prevention efforts in dengue hotspots. This study investigated environmental and socioeconomic factors associated with dengue cases in El Salvador. Dengue cases were obtained from 2011 to 2013 for 262 municipalities. The mean incidence was determined for each municipality for the 3 year period. Negative binomial regression models evaluated the relationship between dengue cases and the environmental factors elevation, forest coverage, mean annual temperature, and cumulative precipitation. Twelve socioeconomic and infrastructure variables and their relationship with dengue were also investigated by using negative binomial regression. A total of 29,764 confirmed dengue cases were reported. The mean dengue incidence for 2011-2013 was 135/100,000. The highest number of dengue cases occurred in San Salvador and surrounding municipalities, as well as in two additional cities, Santa Ana and San Miguel; the highest incidence of dengue cases (per 100,000) occurred in cities in the west and at the center of the country. Significant environmental variables associated with dengue included temperature, precipitation, and non-forested area. The socioeconomic variables poverty rate, illiteracy rate, and school attendance, and the infrastructure variables percent of homes with sanitary service, municipal trash service, electricity, and cement brick flooring, as well as population density, were also significant predictors of dengue. Understanding these environmental and socioeconomic factors and their relationship with dengue will help design and implement timely prevention strategies and vector control to reduce dengue in El Salvador.

Quit Experiences among Primary Care Patients Enrolled in a Smoking Cessation Pilot RCT Early in the COVID-19 Pandemic.

The impact of the COVID-19 pandemic on US adults' smoking and quitting behaviors is unclear. We explored the impact of COVID-19 on smoking behaviors, risk perceptions, and reactions to text messages during a statewide stay-at-home advisory among primary care patients who were trying to quit. From May-June 2020, we interviewed smokers enrolled in a 12-week, pilot cessation trial providing text messaging and mailed nicotine replacement medication (NCT04020718). Twenty-two individuals (82% white, mean age 55 years), representing 88% of trial participants during the stay-at-home advisory, completed exit interviews; four (18%) of them reported abstinence. Interviews were thematically analyzed by two coders. COVID-19-induced environmental changes had mixed effects, facilitating quitting for some and impeding quitting for others. While stress increased for many, those who quit found ways to cope with stress. Generally, participants felt at risk for COVID-19 complications but not at increased risk of becoming infected. Reactions to COVID-19 and quitting behaviors differed across age groups, older participants reported difficulties coping with isolation (e.g., feeling disappointed when a text message came from the study and not a live person). Findings suggest that cessation interventions addressing stress and boredom are needed during COVID-19, while smokers experiencing isolation may benefit from live-person supports.

Wolbachia in mosquitoes from the Central Valley of California, USA.

BACKGROUND: Wolbachia bacteria are widely distributed throughout terrestrial arthropod species. These bacteria can manipulate reproduction and influence the vector competence of their hosts. Recently, Wolbachia have been integrated into vector control programmes for mosquito management. A number of supergroups and strains exist for Wolbachia, and they have yet to be characterized for many mosquito species. In this study, we examined Wolbachia prevalence and their phylogenetic relationship to other Wolbachia, using mosquitoes collected in Merced County in the Central Valley of California. METHODS: Adult mosquitoes were collected from 85 sites in Merced County, California in 2017 and 2018. Traditional and quantitative PCR were used to investigate the presence or absence and the density of Wolbachia, using Wolbachia-specific 16S rRNA and Wolbachia-surface protein (wsp) genes. The supergroup of Wolbachia was determined, and Multilocus Sequence Typing (MLST) by sequencing five housekeeping genes (coxA, gatB, ftsZ, hcpA and fbpA) was also used to determine Wolbachia supergroup as well as strain. RESULTS: Over 7100 mosquitoes of 12 species were collected: Aedes melanimon, Ae. nigromaculis, Ae. vexans, Ae. aegypti, Culex pipiens, Cx. stigmatosoma, Cx. tarsalis, Anopheles franciscanus, An. freeborni, An. punctipennis, Culiseta incidens and Cs. inornata. Eight showed evidence of Wolbachia. To our knowledge, this study is the first to report detection of Wolbachia in five of these species (Ae. melanimon, Cx. stigmatosoma, Cx. tarsalis, Cs. incidens and Cs. inornata). Culex pipiens and Cx. stigmatosoma had a high frequency and density of Wolbachia infection, which grouped into supergroup B; Cs. inornata clustered with supergroup A. MLST comparisons identified Cx. pipiens and Cx. stigmatosoma as wPip strain type 9 supergroup B. Six species had moderate to low (< 14%) frequencies of Wolbachia. Four species were negative, Ae. nigromaculis, An. franciscanus, An. freeborni and Ae. aegypti. CONCLUSIONS: New records of Wolbachia detection were found in mosquitoes from Merced County, California. Culex stigmatosoma and Cs. inornata were new records for Wolbachia supergroup B and A, respectively. Other species with Wolbachia occurred with low frequency and low density. Detection of Wolbachia in mosquitoes can be used to inform potential vector control applications. Future study of Wolbachia within Cx. stigmatosoma and Cs. inornata in California and through the range of these species could further explore Wolbachia infection in these two species.

Assessing Feeding Damage from Two Leaffooted Bugs, Leptoglossus clypealis Heidemann and Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae), on Four Almond Varieties.

Leaffooted bugs (Leptoglossus spp; Hemiptera: Coreidae) are phytophagous insects native to the Western Hemisphere. In California, Leptoglossus clypealis and Leptoglossus zonatus are occasional pests on almonds. Early season feeding by L. clypealis and L. zonatus leads to almond drop, while late season feeding results in strikes on kernels, kernel necrosis, and shriveled kernels. A field cage study was conducted to assess feeding damage associated with L. clypealis and L. zonatus on four almond varieties, Nonpareil, Fritz, Monterey, and Carmel. The objectives were to determine whether leaffooted bugs caused significant almond drop, to pinpoint when the almond was vulnerable, and to determine the final damage at harvest. Branches with ~20 almonds were caged and used to compare almond drop and final damage in four treatments: (1) control branches, (2) mechanically punctured almonds, (3) adult Leptoglossus clypealis, and (4) adult Leptoglossus zonatus. Replicates were set up for eight weeks during two seasons. Early season feeding resulted in higher almond drop than late season, and L. zonatus resulted in greater drop than L. clypealis. The almond hull width of the four varieties in the study did not influence susceptibility to feeding damage. The final damage assessment at harvest found significant levels of kernel strikes, kernel necrosis, and shriveled almonds in bug feeding cages, with higher levels attributed to L. zonatus than L. clypealis. Further research is warranted to develop an Integrated Pest Management program with reduced risk controls for L. zonatus.

Diatraea saccharalis history of colonization in the Americas. The case for human-mediated dispersal.

The sugarcane borer moth, Diatraea saccharalis, is one of the most important pests of sugarcane and maize crops in the Western Hemisphere. The pest is widespread throughout South and Central America, the Caribbean region and the southern United States. One of the most intriguing features of D. saccharalis population dynamics is the high rate of range expansion reported in recent years. To shed light on the history of colonization of D. saccharalis, we investigated the genetic structure and diversity in American populations using single nucleotide polymorphism (SNPs) markers throughout the genome and sequences of the mitochondrial gene cytochrome oxidase (COI). Our primary goal was to propose possible dispersal routes from the putative center of origin that can explain the spatial pattern of genetic diversity. Our findings showed a clear correspondence between genetic structure and the geographical distributions of this pest insect on the American continents. The clustering analyses indicated three distinct groups: one composed of Brazilian populations, a second group composed of populations from El Salvador, Mexico, Texas and Louisiana and a third group composed of the Florida population. The predicted time of divergence predates the agriculture expansion period, but the pattern of distribution of haplotype diversity suggests that human-mediated movement was most likely the factor responsible for the widespread distribution in the Americas. The study of the early history of D. saccharalis promotes a better understanding of range expansion, the history of invasion, and demographic patterns of pest populations in the Americas.

Environmental and Sociological Factors Associated with the Incidence of West Nile Virus Cases in the Northern San Joaquin Valley of California, 2011-2015.

Environmental and socioeconomic risk factors associated with the incidence of human West Nile virus (WNV) cases were investigated in the Northern San Joaquin Valley region of California, a largely rural area. The study included human WNV cases from the years 2011 to 2015 in the three-county area of San Joaquin, Stanislaus, and Merced Counties, and used census tracts as the unit of analysis. Environmental factors included temperature, precipitation, and WNV-positive mosquito pools. Socioeconomic variables included age, housing age, housing foreclosures, median income, and ethnicity. Chi-square independence tests were used to examine whether each variable was associated with the incidence of WNV cases using data from the three counties combined. In addition, negative binomial regression revealed that the environmental factors of temperature and precipitation were the strongest predictors of the incidence of human WNV cases, while the socioeconomic factor of ethnicity was a significant predictor as well, and is a factor to consider in prevention efforts. Source reduction of mosquito breeding sites and targeted prevention and education remain key in reducing the risk associated with WNV.

The AASPIRE practice-based guidelines for the inclusion of autistic adults in research as co-researchers and study participants.

As interest in autism in adulthood grows, so does the need for methods to promote the inclusion of autistic adults in research. Our objective was to create practice-based guidelines for the inclusion of autistic adults, both as research team members and as study participants. We conducted an institutional ethnography of three closely related research partnerships that used participatory methods with autistic adults over the years 2006-2018. We used an iterative approach which combined discussions with community and academic partners and artifact review. Guidelines to promote the inclusion of autistic adults as co-researchers focus on being transparent about partnership goals, clearly defining roles and choosing partners, creating processes for effective communication and power-sharing, building and maintaining trust, disseminating findings, encouraging community capacitation, and fairly compensating partners. Guidelines to promote the inclusion of autistic adults as study participants focus on maximizing autonomy and inclusion, creating an accessible consent process, offering multiple modes of participation, adapting survey instruments for use with autistic adults, creating accessible qualitative interview guides, and handling data from proxy reporters. Although these practice-based guidelines may not apply to all research teams, we hope that other researchers can capitalize on these practical lessons when including autistic adults in research.

Do assortative mating and immigrant inviability help maintain population genetic structuring of an herbivore on a crop and a wild relative?

Population genetic structuring is common among herbivorous insects and frequently is associated with divergent host plants, such as crops and their wild relatives. Previous studies showed population genetic structuring in corn leafhopper Dalbulus maidis in Mexico, such that the species consists of two sympatric, host plant-associated populations: an abundant and widespread "pestiferous" population on maize (Zea mays mays), and a small and localized "wild" population on perennial teosinte (Zea diploperennis), a maize wild relative with a limited distribution. This study addressed whether assortative mating and immigrant inviability mediate genetic structuring of corn leafhopper by comparing the mating and reproductive successes of pestiferous and wild females that colonize their nonassociated host plants against the successes of females colonizing their associated host plants. Assortative mating was assessed by comparing mating frequencies and premating and mating times among females of each population on each host plant; immigrant inviability was assessed by comparing, across two generations, the fecundity, survival, development time, sex ratio, and population growth rate among leafhopper populations and host plants. Our results showed that on maize, and compared to resident, pestiferous females, wild females were more likely to mate, and greater proportions of their offspring survived to adult stage and were daughters; consequently, the per-generation population growth rate on maize was greater for immigrant, wild leafhoppers compared to resident, pestiferous leafhoppers. Our results suggested that wild leafhoppers emigrating to maize have a fitness advantage over resident, pestiferous leafhoppers, while immigrant pestiferous and resident wild leafhoppers on teosinte have similar fitnesses.

Genetic variability of the Aedes aegypti (Diptera: Culicidae) mosquito in El Salvador, vector of dengue, yellow fever, chikungunya and Zika.

BACKGROUND: Aedes aegypti is associated with dengue, yellow fever, chikungunya and Zika viruses. This vector is widespread in tropical and subtropical areas, and can also occur in temperate areas at higher latitudes. The geographical distribution of Ae. aegypti continues to spread due to human activities. This is the first study to examine the population genetic structure of this insect in El Salvador, Central America. METHODS: Aedes aegypti larvae were collected from six geographical regions of El Salvador: Sonsonate, San Salvador, Chalatenango, Usulután, San Miguel and Morazán. Larvae were raised into adults, identified and preserved. Two molecular markers, amplified fragment length polymorphism (AFLP) genotyping and mitochondrial DNA (mtDNA) cytochrome c oxidase subunit 1 (cox1) sequencing, were used to investigate population genetic structure. RESULTS: Structure analysis found two genetically distinct populations; one occurs predominantly in the north and west, and a mix of two populations occurs in the southeast of the country. Genetic distances ranged from 0.028 (2.8%) to 0.091 (9%), and an AMOVA analysis found 11% variation between populations. Mitochondrial DNA cox1 sequences produced a haplotype network which consisted of 3 haplogroups and 10 haplotypes. Haplogroup 1 had low haplotype and nucleotide diversity and was found in all six regions. Haplogroups 2 and 3 had higher haplotype and nucleotide diversity, and were less abundant; haplogroup 3 was found in only 3 of the six regions studied. Bottleneck tests were significant, suggesting that populations had undergone a recent bottleneck. A maximum likelihood tree, which combined samples from this study with available sequences in GenBank, suggested that two genetically divergent lineages had been introduced. CONCLUSIONS: Relatively high genetic diversity was found in Ae. aegypti in El Salvador. The mtDNA sequences clustered into two lineages, as found in previous studies. Samples in El Salvador may be introduced from regions in North and South America where past eradication was not complete. Future study of genotypes in surrounding countries would provide a more complete picture of the movement and potential source of introductions of this vector. The distribution of the lineages and haplogroups may further our understanding of the epidemiology of Ae. aegypti associated vector borne diseases.

Population genetic structure of the Culex pipiens (Diptera: Culicidae) complex, vectors of West Nile virus, in five habitats.

BACKGROUND: The Culex pipiens complex consists of several morphologically similar, closely related species. In the United States, Cx. pipiens L. is distributed North of 39° latitude, while Cx. quinquefasciatus Say occurs South of 36° latitude; a hybrid zone occurs between these two latitudes including in the Central Valley of California. Members of the Cx. pipiens complex and their hybrids are vectors for West Nile virus (WNv). Hybrid offspring of Cx. pipiens and Cx. quinquefasciatus have been found to have enhanced transmission rates of WNv over those of pure populations of each species. We investigated whether hybrids of Cx. pipiens and Cx. quinquefasciatus occurred more frequently in any of five habitats which were dairies, rural, suburban, and urban areas, and wetlands. In addition, the proportion of alleles unique to Cx. quinquefasciatus and Cx. pipiens found in each habitat-associated population were determined. METHODS: Amplified fragment length polymorphism (AFLP) markers were used to compare the population structure of the Cx. pipiens complex from each habitat to geographically distant populations considered pure Cx. pipiens and Cx. quinquefasciatus. Structure analyses were used to assign individuals to either Cx. pipiens, Cx. quinquefasciatus, or hybrids of the Cx. pipiens complex. The ancestry of hybrids (F1, F2, or backcrossed) in relation to the two parent populations was estimated for each Central Valley population. Loci unique to the pure Cx. pipiens population and the pure Cx. quinquefasciatus population were determined. The proportion of loci unique to Cx. pipiens and Cx. quinquefasciatus populations were subsequently determined for each population from the five Merced habitats and from the Oroville California population. The unique loci found in Merced populations and not in Cx. pipiens or Cx. quinquefasciatus were also determined. A principal components analysis was run, as was an analysis to determine loci under putative selection. RESULTS: The Structure Harvester analysis found K = 3, and the Culex pipiens complex mosquitoes formed a genetic cluster distinct from Cx. quinquefasciatus and Cx. pipiens. Individuals collected from each habitat were nearly all hybrids. However, Cx. pipiens complex collected near dairies had more individuals categorized as Cx. pipiens than collections from the other habitats. None of the mosquitoes collected in Merced or Oroville were considered pure Cx. quinquefasciatus. Significant genetic divergence was detected among the Cx. pipiens complex from the five habitats in Merced; Cx. pipiens complex mosquitoes from dairies were divergent from the urban and suburban populations. New Hybrids analysis found that individuals from all five Merced habitat-associated populations and the population from Oroville were primarily categorized as hybrids backcrossed to the Cx. pipiens population. Finally, all five habitat-associated populations shared more alleles with Cx. pipiens than with Cx. quinquefasciatus, even though the pure Cx. quinquefasciatus population was more geographically proximate to Merced. Results from the principal component analysis, and the occurrence of several unique loci in Merced populations, suggest that Cx. pipiens molestus may also occur in the habitats sampled. CONCLUSIONS: Nearly all mosquitoes in the five habitats in Merced in the Central Valley of California area were hybrids of Cx. pipiens and Cx. quinquefasciatus, consisting of hybrids backcrossed to Cx. pipiens. Habitat-associated mosquitoes collected near dairies had more individuals consisting of pure Cx. pipiens, and no mosquitoes from Merced or Oroville CA classified as pure Cx. quinquefasciatus. The genetic distances among Cx. pipiens and Cx. quinquefasciatus, and hybrid populations agree with previous studies using other molecular markers. Cx. pipiens hybrids in Merced shared more alleles with Cx. pipiens than Cx. quinquefasciatus which was unexpected, since Merced is geographically closer to the northern limit of Cx. quinquefasciatus distribution. Culex pipiens molestus may occur in more habitats in the Central Valley than previously suspected, which warrants further investigation. Future studies could investigate the vector competence of hybrids backcrossed to either Cx. pipiens or Cx. quinquefasciatus parent for their ability to transmit West Nile virus.

Host-plant associated genetic divergence of two Diatraea spp. (Lepidoptera: Crambidae) stemborers on novel crop plants.

Diatraea lineolata and Diatraea saccharalis (Lepidoptera: Crambidae) are moths with stemboring larvae that feed and develop on economically important grasses. This study investigated whether these moths have diverged from a native host plant, corn, onto introduced crop plants including sorghum, sugarcane, and rice. Diatraea larvae were collected from these four host plants throughout the year in El Salvador and were reared on artificial diet until moths or parasitoids emerged. Adult moths were subsequently identified to species. Amplified fragment length polymorphisms (AFLPs) and mitochondrial DNA cytochrome oxidase I (COI) were used to examine whether or not there was genetic divergence of D. lineolata or D. saccharalis populations on the four host plants. Percent parasitism was also determined for each moth on its host plants. D. lineolata was collected from corn in the rainy season and sorghum in the dry season. D. saccharalis was most abundant on sugarcane in the rainy season and sorghum in the dry season. The AFLP analysis found two genetically divergent populations of both D. lineolata and D. saccharalis. Both moths had high levels of parasitism on their dominant host plant in the rainy season, yet had low levels of parasitism on sorghum in the dry season. The presence of two genotypes of both Diatraea spp. on sorghum suggest that host-associated differentiation is occurring on this novel introduced crop plant.

Geographic population structure of the sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), in the southern United States.

The sugarcane borer moth, Diatraea saccharalis, is widespread throughout the Western Hemisphere, and is considered an introduced species in the southern United States. Although this moth has a wide distribution and is a pest of many crop plants including sugarcane, corn, sorghum and rice, it is considered one species. The objective was to investigate whether more than one introduction of D. saccharalis had occurred in the southern United States and whether any cryptic species were present. We field collected D. saccharalis in Texas, Louisiana and Florida in the southern United States. Two molecular markers, AFLPs and mitochondrial COI, were used to examine genetic variation among these regional populations and to compare the sequences with those available in GenBank and BOLD. We found geographic population structure in the southern United States which suggests two introductions and the presence of a previously unknown cryptic species. Management of D. saccharalis would likely benefit from further investigation of population genetics throughout the range of this species.