There have been numerous changes in the nomenclature of species of Dendroctonus. The case of Dendroctonus parallelocollis Chapuis and Dendroctonus approximatus Dietz has been particularly noteworthy. These bark beetles colonize pine trees but are not aggressive species. The high morphological similarity, their overlapping geographical distribution, and the limited knowledge of these species have resulted in taxonomic confusion. The aim of the present study was to assess morphological characters reported in the literature and to scrutinize new characters that might be useful for the separation of these species. We evaluated 26 morphological attributes and performed geometric morphometrics analysis of the antenna, pronotum, spermatheca, and seminal rod to test if the variations in the shape of these structures allow the recognition of additional discrete characters to differentiate them. Our results show that five double-state characters of external morphology are useful to identify these species, and the shape of antenna, spermatheca, and seminal rod.

Dendroctonus bark beetles (Scolytinae) are one of the most important disturbance agents of coniferous forests in North and Central America. These beetles spend their lives almost entirely under the tree bark, and their survival and reproductive success depend on their ability to overcome the toxic effect of the trees’ oleoresin. The cytochromes P450 (CYPs) are associated with the detoxification process of xenobiotics, as well as other physiological processes. Different cytochromes (families 4, 6, and 9) in the Dendroctonus species have been expressed under several experimental conditions; nevertheless, the expression time-course of these genes is unknown. To explore the induction speed of CYPs, we evaluated the relative expression of the CYP6BW5, CYP6DG1, CYP6DJ2, CYP9Z18, and CYP9Z20 genes at the early hours of drilling and settling into a tree (1, 2, 4, 6, 8, 12, 18 h) both in females and males, solitary or paired, of the bark beetle Dendroctonus rhizophagus Thomas and Bright. Our findings show that the five genes were rapidly overexpressed in the early hours (1 to 6 h) in both sexes and in solitary and paired conditions, suggesting their participation in the detoxification process. Additionally, the CYPs expression shows up- and down-regulation patterns through these short times, suggesting their probable participation in other physiological processes as the biosynthesis of hormones, pheromones or compounds related to reproduction.

Bark beetles commonly produce de novo terpenoid pheromones using precursors synthesized through the mevalonate pathway. This process is regulated by Juvenile Hormone III (JH III). In this work, the expression levels of mevalonate pathway genes were quantified after phloem feeding—to induce the endogenous synthesis of JH III—and after the topical application of a JH III solution. The mevalonate pathway genes from D. rhizophagus were cloned, molecularly characterized, and their expression levels were quantified. Also, the terpenoid compounds produced in the gut were identified and quantified by Gas Chromatography Mass Spectrometry (GC-MS). The feeding treatment produced an evident upregulation, mainly in acetoacetyl-CoA thiolase (AACT), 3-hydroxy-3-methylglutaryl-CoA synthase (HMGS), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), phosphomevalonate kinase (PMK), and isopentenyl diphosphate isomerase (IPPI) genes, and males reached higher expression levels compared to females. In contrast, the JH III treatment did not present a clear pattern of upregulation in any sex or time. Notably, the genes responsible for the synthesis of frontalin and ipsdienol precursors (geranyl diphosphate synthase/farnesyl diphosphate synthase (GPPS/FPPS) and geranylgeranyl diphosphate synthase (GGPPS)) were not clearly upregulated, nor were these compounds further identified. Furthermore, trans-verbenol and myrtenol were the most abundant compounds in the gut, which are derived from an α-pinene transformation rather than de novo synthesis. Hence, the expression of mevalonate pathway genes in D. rhizophagus gut is not directed to the production of terpenoid pheromones, regardless of their frequent occurrence in the genus Dendroctonus.

COVID-19 vaccines prevented severe disease outcomes worldwide. As part of a vaccine effectiveness study, the authors summarized demographic and health profiles, vaccination data, SARS-CoV-2 variants, and disease outcomes from patients hospitalized due to COVID-19-like symptoms in Latin America between February and December 2022. LIVE was an observational-prospective study with a test-negative case-control design (NCT05282017). Adults admitted with COVID-19-like symptoms were recruited across five Latin American countries. Patients were tested for SARS-CoV-2, and variants were identified through sequencing. Data were collected from medical records and interviews. Participants recruited (536 cases, 250 controls) had a mean age of 60.5 years. COVID-19 cases (63.7, SD = 19.1) were slightly older than controls (53.8, SD = 20.4). Disorders of the cardiovascular system were the most prevalent comorbidities, and most participants (73.0 %) reported at least one comorbidity. COVID-19 cases mostly presented with moderate (51.1 %) disease. Overall, 50.6 % of participants were unvaccinated against COVID-19, with a higher percentage in cases (56.3 %) than in controls (38.2 %). Viral genomic analysis identified the most prevalent SARS-CoV-2 lineages, BQ.1.1 (11.9 %) among Omicron BA.5 and XBB.1.15 (2.5 %) among recombinant variants. The study was underpowered to estimate vaccine effectiveness due to the low number of COVID-19 hospitalization cases. The present study revealed key demographic and clinical characteristics of patients hospitalized due to COVID-19. Notably, an older age among confirmed cases, a substantial proportion of unvaccinated individuals, and the decrease in hospitalizations emphasize the complexity of the COVID-19 landscape in Latin America and the need for continued research to inform public health strategies.