A Four-Year, Seven-State Reforestation Trial with Eastern Hemlocks (\u3cem\u3eTsuga canadensis\u3c/em\u3e) Resistant to Hemlock Woolly Adelgid (\u3cem\u3eAdelges tsugae\u3c/em\u3e)

We conducted over a decade of research into individual eastern hemlock (Tsuga canadensis; hemlock) trees that are potentially resistant to hemlock woolly adelgid (Adelges tsugae; HWA), an invasive xylem-feeding insect that is capable of rapidly killing even mature trees. Following clonal propagation of these individuals, in 2015 we planted size- and age-matched HWA-resistant and HWA-susceptible hemlocks in HWA-infested forest plots in seven states. In 2019, we re-surveyed the plots; 96% of HWA-resistant hemlocks survived compared to 48% of susceptible trees. The surviving HWA-resistant trees were also taller, produced more lateral growth, retained more foliage, and supported lower densities of the elongate hemlock scale Fiorinia externa, another invasive hemlock pest, than the surviving HWA-susceptible trees. Our results suggest that HWA management may benefit from additional research exploring the identification, characterization, and use of HWA-resistant eastern hemlocks in future reforestation efforts

Failure Under Stress: The Effect of the Exotic Herbivore \u3cem\u3eAdelges tsugae\u3c/em\u3e on Biomechanics of \u3cem\u3eTsuga canadensis\u3c/em\u3e

Background and Aims Exotic herbivores that lack a coevolutionary history with their host plants can benefit from poorly adapted host defences, potentially leading to rapid population growth of the herbivore and severe damage to its plant hosts. The hemlock woolly adelgid (Adelges tsugae) is an exotic hemipteran that feeds on the long-lived conifer eastern hemlock (Tsuga canadensis), causing rapid mortality of infested trees. While the mechanism of this mortality is unknown, evidence indicates that A. tsugae feeding causes a hypersensitive response and alters wood anatomy. This study investigated the effect of A. tsugae feeding on biomechanical properties at different spatial scales: needles, twigs and branches. Methods Uninfested and A. tsugae-infested samples were collected from a common garden experiment as well as from naturally infested urban and rural field sites. Tension and flexure mechanical tests were used to quantify biomechanical properties of the different tissues. In tissues that showed a significant effect of herbivory, the potential contributions of lignin and tissue density on the results were quantified. Key Results Adelges tsugae infestation decreased the abscission strength, but not flexibility, of needles. A. tsugae feeding also decreased mechanical strength and flexibility in currently attacked twigs, but this effect disappeared in older, previously attacked branches. Lignin and twig tissue density contributed to differences in mechanical strength but were not affected by insect treatment. Conclusions Decreased strength and flexibility in twigs, along with decreased needle strength, suggest that infested trees experience resource stress. Altered growth patterns and cell wall chemistry probably contribute to these mechanical effects. Consistent site effects emphasize the role of environmental variation in mechanical traits. The mechanical changes measured here may increase susceptibility to abiotic physical stressors in hemlocks colonized by A. tsugae. Thus, the interaction between herbivore and physical stresses is probably accelerating the decline of eastern hemlock, as HWA continues to expand its range

Effects of Physician-Based Preventive Oral Health Services on Dental Caries

Most Medicaid programs reimburse nondental providers for preventive dental services. We estimate the impact of comprehensive preventive oral health services (POHS) on dental caries among kindergarten students, hypothesizing improved oral health among students with medical visits with POHS

Impact of Hemlock Woolly Adelgid (Hemiptera: Adelgidae) Infestation on the Jasmonic Acid-Elicited Defenses of Tsuga canadensis (Pinales: Pinaceae)

Hemlock woolly adelgid is an invasive piercing-sucking insect in eastern North America, which upon infestation of its main host, eastern hemlock (‘hemlock’), improves attraction and performance of folivorous insects on hemlock. This increased performance may be mediated by hemlock woolly adelgid feeding causing antagonism between the the jasmonic acid and other hormone pathways. In a common garden experiments using hemlock woolly adelgid infestation and induction with methyl jasmonate (MeJA) and measures of secondary metabolite contents and defense-associated enzyme activities, we explored the impact of hemlock woolly adelgid feeding on the local and systemic induction of jasmonic acid (JA)-elicited defenses. We found that in local tissue hemlock woolly adelgid or MeJA exposure resulted in unique induced phenotypes, whereas the combined treatment resulted in an induced phenotype that was a mixture of the two individual treatments. We also found that if the plant was infested with hemlock woolly adelgid, the systemic response of the plant was dominated by hemlock woolly adelgid, regardless of whether MeJA was applied. Interestingly, in the absence of hemlock woolly adelgid, hemlock plants had a very weak systemic response to MeJA. We conclude that hemlock woolly adelgid infestation prevents systemic induction of JA-elicited defenses. Taken together, compromised local JA-elicited defenses combined with weak systemic induction could be major contributors to increased folivore performance on hemlock woolly adelgid-infested hemlock

Facilitation between invasive herbivores: hemlock woolly adelgid increases gypsy moth preference for and performance on eastern hemlock

Interactions between invertebrate herbivores with different feeding modes are common on long‐lived woody plants. In cases where one herbivore facilitates the success of another, the consequences for their shared host plant may be severe. Eastern hemlock (Tsuga canadensis), a canopy‐dominant conifer native to the eastern U.S., is currently threatened with extirpation by the invasive stylet‐feeding hemlock woolly adelgid (Adelges tsugae). The effect of adelgid on invasive hemlock‐feeding folivores remains unknown. This study evaluated the impact of feeding by hemlock woolly adelgid on gypsy moth (Lymantria dispar) larval preference for, and performance on, eastern hemlock. To assess preference, 245 field‐grown hemlocks were surveyed for gypsy moth herbivory damage and laboratory paired‐choice bioassays were conducted. To assess performance, gypsy moth larvae were reared to pupation on adelgid‐infested or uninfested hemlock foliage, and pupal weight, proportional weight gain, and larval period were analysed. Adelgid‐infested hemlocks experienced more gypsy moth herbivory than did uninfested control trees, and laboratory tests confirmed that gypsy moth larvae preferentially feed on adelgid‐infested hemlock foliage. Gypsy moth larvae reared to pupation on adelgid‐infested foliage gained more weight than larvae reared on uninfested control foliage. These results suggest that the synergistic effect of adelgid and gypsy moth poses an additional threat to eastern hemlock that may increase extirpation risk and ecological impact throughout most of its range

A Potential Biofilm Metabolite Signature for Caries Activity - A Pilot Clinical Study

BACKGROUND: This study's aim was to compare the dental biofilm metabolite-profile of caries-active (N=11) or caries-free (N=4) children by gas chromatography-mass spectrometry (GC/MS) analyses. METHODS: Samples collected after overnight fasting, with or without a previous glucose rinse, were combined for each child based on the caries status of the site, re-suspended in ethanol and analyzed by GC/MS. RESULTS: Biofilm from caries-active sites exhibited a different chromatographic profile compared to caries-free sites. Qualitative and quantitative analysis suggested a special cluster of branched alcohols and esters present at substantially higher intensity in biofilms of caries-active sites. CONCLUSIONS: This pilot study indicates that there are metabolites present in the biofilm which have the potential to provide a characteristic metabolomics signature for caries activity

Seasonal changes in eastern hemlock (\u3cem\u3eTsuga canadensis\u3c/em\u3e) foliar chemistry

Eastern hemlock (Tsuga canadensis (L.) Carriére; hemlock) is an eastern North American conifer threatened by the invasive hemlock woolly adelgid (Adelges tsugae Annand). Changes in foliar terpenes and phenolics were evaluated in new (current year growth) and mature (1-year old growth) hemlock needles during the growing season and into plant dormancy. From April through September, foliar concentrations of non-volatile soluble phenolics, condensed tannins, lignin, mono- and sesquiterpenes α-pinene, camphene, isobornyl acetate, and diterpene resin were quantified. After September, additional analyses of metabolites that continued to differ significantly in new versus mature foliage were carried out. Total soluble phenolic concentration and condensed tannin concentration in new foliage remained low relative to mature foliage throughout the growing season and converged in December. Lignin concentration in new foliage converged with that of mature foliage by July. Concentrations of α-pinene, camphene, isobornyl acetate, and diterpene resin in new foliage converged with mature foliage within one month of budbreak. The convergence of terpene concentrations in new and mature foliage suggests that these metabolites may play a role in herbivore defense during the peak growing season. Conversely, soluble phenolics, including condensed tannins, may defend foliage from herbivory outside of the spring growth period

Preventive Services by Medical and Dental Providers and Treatment Outcomes

Objective: Nearly all state Medicaid programs reimburse nondental primary care providers (PCPs) for providing preventive oral health services to young children; yet, little is known about how treatment outcomes compare with children visiting dentists. This study compared the association between the provider of preventive services (PCP, dentist, or both) with Medicaid-enrolled children before their third birthday and subsequent dental caries-related treatment (CRT) and CRT payment. Methods: We conducted a retrospective study of young children enrolled in North Carolina Medicaid during 2000 to 2006. The annual number of CRT and CRT payments per child between the ages of 3 and 5 yr were estimated with a zero-inflated negative binomial regression and a hurdle model, respectively. Models were adjusted for relevant child- and county-level characteristics and used propensity score weighting to address observed confounding. Results: We examined 41,453 children with > 1 preventive oral health visit from a PCP, dentist, or both before their third birthday. Unadjusted annual mean CRT and payments were lowest among children who had only PCP visits (CRT = 0.87, payment = $172) and higher among children with only dentist visits (CRT = 1.48, payment =$234) and both PCP and dentist visits (CRT = 1.52, payment = $273). Adjusted results indicated that children who had dentist visits (with or without PCP visits) had significantly more CRT and higher CRT payments per year during the ages of 3 and 4 yr than children who had only PCP visits. However, these differences attenuated each year after age 3 yr. Conclusions: Because of children’s increased opportunity to receive multiple visits in medical offices during well-child visits, preventive oral health services provided by PCPs may lead to a greater reduction in CRT than dentist visits alone. This study supports guidelines and reimbursement policies that allow preventive dental visits based on individual needs

The Many Faces of Fear: Comparing the Pathways and Impacts of Nonconsumptive Predator Effects on Prey Populations

Background: Most ecological models assume that predator and prey populations interact solely through consumption: predators reduce prey densities by killing and consuming individual prey. However, predators can also reduce prey densities by forcing prey to adopt costly defensive strategies. Methodology/Principal Findings: We build on a simple Lotka-Volterra predator-prey model to provide a heuristic tool for distinguishing between the demographic effects of consumption (consumptive effects) and of anti-predator defenses (nonconsumptive effects), and for distinguishing among the multiple mechanisms by which anti-predator defenses might reduce prey population growth rates. We illustrate these alternative pathways for nonconsumptive effects with selected empirical examples, and use a meta-analysis of published literature to estimate the mean effect size of each pathway. Overall, predation risk tends to have a much larger impact on prey foraging behavior than measures of growth, survivorship, or fecundity. Conclusions/Significance: While our model provides a concise framework for understanding the many potential NCE pathways and their relationships to each other, our results confirm empirical research showing that prey are able to partially compensate for changes in energy income, mitigating the fitness effects of defensive changes in time budgets. Distinguishing the many facets of nonconsumptive effects raises some novel questions, and will help guide both empirica

Children's oral health-related behaviours and early childhood caries: A latent class analysis

Objective: In this cross-sectional study in a large community-based sample of preschool-age children, we sought to identify distinct clusters of modifiable early childhood oral health-related behaviours (OHBs) and quantify their association with clinical and parent-reported measures of early childhood oral health. Methods: We relied upon a questionnaire (n = 8033; 11% in Spanish) and clinical oral health data (n = 6404; early childhood caries [ECC] prevalence = 54%] collected in the context of an epidemiologic study of early childhood oral health among 3- to 5-year-old children in North Carolina. Latent class analysis was used to identify clusters of modifiable OHBs based on parents' responses to 6 questionnaire items pertaining to their children's oral hygiene, diet and dental home. The optimal number of clusters was determined based on measures of model fit and interpretability. We examined associations of OHB clusters with clinical and parent-reported child oral health status (ie, ECC prevalence, severity and proportion with untreated disease) using bivariate association tests and multivariable regression modelling with marginal effects estimation accounting for clustered data. We used Mplus v.8.6 (Muthén & Muthén, Los Angeles, CA, USA) and Stata v.16.1 (StataCorp, College Station, TX, USA) for data analyses. Results: We identified 2 OHB clusters, a favourable (74%) and an unfavourable (26%) one. Children in the favourable OHB cluster had better oral hygiene practices (ie, tooth brushing frequency and fluoridated toothpaste use), lower consumption frequency of sugar-containing snacks and beverages, less frequent reports of night-time bottle-feeding history and a higher likelihood of a dental home. Children in the unfavourable cluster had significantly higher ECC prevalence (57% vs 53%), caries burden (mean dmfs = 9.3 vs 7.6), untreated disease (43% vs 33%) and worse parent-reported oral health status than the favourable cluster. Conclusions: Our findings demonstrate the importance and utility of clustering common, modifiable ECC risk factors in population studies - health promotion efforts may centre on groups of people rather than individual behavioural risk factors