Biological invasions are a form of global change threatening biodiversity, ecosystem stability, and human health, and cost government agencies billions of dollars in remediation and eradication programs. Attempts to eradicate introduced species are most successful when detection of newly established populations occurs early in the invasion process. We review existing and emerging tools -specifically environmental DNA (eDNA), chemical approaches, remote sensing, citizen science, and agency-based monitoring -for surveillance and monitoring of invasive species. For each tool, we consider the benefits provided, examine challenges and limitations, discuss data sharing and integration, and suggest best practice implementations for the early detection of invasive species. Programs that promote public participation in large-scale biodiversity identification and monitoring (such as iNaturalist and eBird) may be the best resources for early detection. However, data from these platforms must be monitored and used by agencies that can mount appropriate response efforts. Control efforts are more likely to succeed when they are focused on early detection and prevention, thereby saving considerable time and resources.

In 2015 and 2016, Zika virus (ZIKV) swept through dengue virus (DENV) endemic areas of Latin America. These viruses are of the same family, share a vector and may interact competitively or synergistically through human immune responses. We examine dengue incidence from Brazil and Colombia before, during, and after the Zika epidemic. We find evidence that dengue incidence was atypically low in 2017 in both countries. We investigate whether subnational Zika incidence is associated with changes in dengue incidence and find mixed results. Using simulations with multiple assumptions of interactions between DENV and ZIKV, we find cross-protection suppresses incidence of dengue following Zika outbreaks and low periods of dengue incidence are followed by resurgence. Our simulations suggest correlations in DENV and ZIKV reproduction numbers could complicate associations between ZIKV incidence and post-ZIKV DENV incidence and that periods of low dengue incidence are followed by large increases in dengue incidence.

Little is known about whether glucocorticoids (GC) and GC responsiveness vary on a diel basis in the wild, especially for fish. Using bluegill (Lepomis macrochirus Rafinesque, 1819) as a model freshwater teleost fish, we tested whether baseline concentration and stress responsiveness of GCs (i.e., plasma glucose and cortisol) varied over a 24 h period. Blood samples from lake-dwelling wild bluegill were obtained across six periods representing a complete circadian cycle to determine GC levels in newly captured fish (i.e., within 3 min of capture; baseline), the maximum value (maximum) 45 min following exposure to a standardized aerial exposure stressor, and determining responsiveness (by subtracting minimum from maximum). Our results revealed that baseline glucose concentration did not vary on a diel basis, whereas baseline cortisol concentration did. Maximum and stress-induced glucose responsiveness varied significantly among several time periods with lowest values recorded at midnight and higher values at mid-day. Maximum and stress-induced cortisol responsiveness were consistent across time periods. Collectively, these data suggest that baseline concentrations and stress-induced values of GCs in a freshwater temperate teleost fish tend to be consistent across diel periods such that there is apparently an absence of strong GC diel patterns.Résumé : Les connaissances sur d'éventuelles variations journalières des glucocorticoïdes (GC) et de la réactivité de ces derniers chez les espèces sauvages, plus particulièrement les poissons, sont très limitées. En se servant du crapet arlequin (Lepomis macrochirus Rafinesque, 1819) comme modèle de poisson téléostéen d'eau douce, nous avons vérifié si la réactivité de fond et au stress des GC (c.-à -d. glucose et cortisol du plasma) variait sur une période de 24 h. Des échantillons sanguins de crapets arlequin sauvages de lac ont été obtenus pour six moments de la journée représentant un cycle circadien complet, afin de déterminer les teneurs en GC dans des poissons tout juste capturés (c.-à -d. dans les 3 min suivant leur capture; valeur de fond), la valeur maximum 45 min après exposition à un stresseur aérien standardisé et la réactivité (en soustrayant la valeur minimum de la valeur maximum). Nos résultats révèlent que les teneurs de fond du glucose ne variaient pas sur une base journalière, contrairement aux teneurs de fond du cortisol. Les réactivités maximum et induite par le stress du glucose variaient de manière significative selon le moment de la journée, les teneurs les plus faibles étant enregistrées à minuit et les plus fortes, au milieu de la journée. Les réactivités maximum et induite par le stress du cortisol étaient uniformes pour les différents moments du jour. Collectivement, ces données donnent à penser que les teneurs de fond et induites par le stress des GC chez un poisson téléostéen d'eau douce de milieu tempéré ont tendance à être uniformes d'un moment de la journée à l'autre, de sorte qu'il ne semble pas y avoir de fortes variations journalières des ...