In their 2019 study, Molina et al. evaluate a cell proliferation assay that fluorescently quantifies DNA for assessing ballast water treatment efficacy of organisms ≥ 10 to 50 µm. Because of concerns with the overall experimental design, procedures, and authors’ interpretations, their conclusions do not appear to be justified and the assay used to arrive at those conclusions is not proven appropriate. Specific concerns we highlight include UV and chlorine dose calculations and exposure conditions, bacterial contamination issues, poor agreement between controls, high detection limit of the assay, and mismatch between conclusions in the abstract and statistical significance of the data. Their conclusions that “population maintenance or growth was evident … after UV treatment” and “photoreactivation could have been attributed to increased mean DNA concentrations” are therefore not scientifically defensible without further experimentation and verification. These concerns call into serious question the use of this study by the US Coast Guard or other governing bodies to (1) determine the applicability of this cell proliferation assay for assessing ballast water disinfection or (2) make conclusions regarding the suitability of UV treatment for inactivating organisms in ballast water.

The East Maui Watershed (EMW) is a > 60,000-ha forested watershed with wide temperature and precipitation gradients being invaded by miconia (Miconia calvescens DC.). Current miconia management efforts focus on protecting important watershed and critical habitat areas from miconia invasion. Herein, we report on a miconia species distribution model to predict unoccupied areas that may be still vulnerable to invasion. This suitable habitat model was developed from an ensemble of five algorithms associating five physical features of EMW with miconia occurrence data from a 26-yr management history (1991–2016; n = 114,953). All of the algorithms performed well based on model evaluation statistics (e.g. AUC ≥ 0.83; TSS ≥ 0.36). Elevation, slope and rainfall were consistently important predictors, while aspect indices were non-contributors. The binary ensemble model suggests a total of ~ 56.9% of the area of interest is susceptible to invasion by miconia. An independent dataset collected in 2017–2018 (n = 5,222) was used to field validate the ensemble habitat suitability model (EHSM) and found that the model could correctly predict suitable habitat 94% of the time. All five of the model algorithms were updated using this new management data, and the predicted suitable area decreased 2.3%. While binary models are useful for risk assessment, the classification of an area as suitable or not suitable has limitations for land managers adopting for management activities. Utilizing the mean weighted consensus probability surface representation of the model allows for more scrutiny of potential suitable habitat. We suggest using this approach when planning future monitoring efforts, especially if specific areas have a higher prioritization for conservation than others.

The invasive brown marmorated stink bug Halyomorpha halys is native to East Asia and was first detected in Switzerland, Europe in 2004. It is now widespread throughout continental Europe and has recently been reported on several islands in the Mediterranean Sea. In the Eastern Mediterranean, it has been recorded in Greece, Turkey and most probably Egypt, but there is no information regarding its occurrence in the Republic of Cyprus. Therefore, in September 2019, a survey at potential points of entry and arrivals was carried out by setting pheromone traps of the pest in the vicinity of airports, harbours as well as next to importers’ trade warehouses in the country. This stink bug monitoring programme in September and October was completed with an awareness campaign, which consisted of the establishment of a citizen science initiative for the early warning of this alien pest by disseminating an alert letter titled “Bug Alert Cyprus” in English and Greek to various target groups. To the best of our knowledge, this is the first CS initiative in Cyprus focusing on the early detection of a polyphagous agricultural and nuisance pest. The lack of H. halys captured during the trapping period, and the absence of reports from citizens seem to indicate that H. halys had not reached this European island country up to January 2020. The methodology we applied and our further recommendations may foster further CS activities combined with targeted trappings to give an early warning and enable the detection of H. halys as effectively as possible on European islands as well as on other remote or isolated parts of the world not yet invaded by this pest.

Early detection of an invasive species is the first critical step to managing their invasion. New Zealand mudsnails (Potamopyrgus antipodarum; hereafter NZMS) are a small gastropod native to New Zealand and a documented worldwide invader. Although many approaches for sampling NZMS have been used, no protocol has emerged as a standard for early detection monitoring in lotic environments. In order to document the occurrence of NZMS, we developed a qualitative sampling methodology and evaluated its effectiveness. The sampling methodology involved conducting two searcher visual surveys along stream margins in a 50-meter search range for a standard 20-minute search time. Qualitative estimates of abundance and the time when the first detection was made were documented by each searcher. We conducted a total of 227 surveys in 12 rivers in Michigan, USA in 2017. Survey data were analyzed using an occupancy model framework, resulting in a per survey detectability exceeding 96%. We ran the occupancy model in an atypical fashion to explore the impact that relative abundance had on detectability. As relative abundance increased, detectability of NZMS increased. We modeled shorter survey durations (i.e., 15, 10, and 5 minutes) to determine their impact on detectability and found that less than 2% of detections were lost when reducing the survey length from 20 to 5 minutes. We developed a novel decision support tool to help understand how the number of sites surveyed, the site level detection probability, and the occupancy level of a rare species interact to determine the overall probability of detection of a new invader. The decision support table can help guide sampling design choices by giving insight into what combination of choices provides the overall highest probability of detection across all sites combined.

Although there is a sizeable budget for biosecurity management in New Zealand, there will never be sufficient resources to intervene in all incursions of harmful species, including invasive freshwater plants. Given the inherent complexity in making decisions on interventions, responses are often decided in relation to specific incursions as they happen within their particular context. This paper uses New Zealand case studies to test if there are general economic principles related to intervention in invasive freshwater plants which can be used to improve decision-making. The general principles were; the sooner eradication is started and/or the smaller the incursion size, the lower the cost will be; eradication is more expensive than alternative responses in the short term but is cheaper than long term impacts of no intervention and/or ongoing control programs; and preventing new incursions is cheaper in the long run than eradication. The three principles were considered to be logical in an economic sense and can contribute to supporting intervention decision-making at a macro-level (i.e. across the majority of incursions) and provide more holistic outcomes for society in relation to management programs.

The combination of snake-proof barriers and an aerial toxicant-delivery system for snake suppression may allow large-scale control of invasive brown treesnakes (Boiga irregularis) on Guam. However, suppression or local eradication of several other species (e.g., introduced ungulates, cats, rodents) may be required for successful restoration and recovery of forest habitat and reintroduction of native fauna. Island-wide eradication of invasive species is unlikely on Guam, and existing snake-proof barriers are largely ineffective against cats, rodents, shrews, or monitor lizards. Improved barrier technology and pest-control tools may together provide a viable solution to support localized restoration of species and habitats. We designed and tested prototype multispecies barriers using materials known to repel ungulates, cats, and rodents, with a focus on testing the ability of a rolled hood installed over three different mesh designs to repel brown treesnakes and black rats (Rattus rattus). Woven wire (4.9 × 12 mm aperture, 2.5 mm dia. wire) repelled 99.1% of all snakes, including ≥ 1031 breach attempts by 106 individuals and 2 successful breaches by 1 small individual. Woven wire (6 × 6 mm aperture, 2.7 mm dia. wire) repelled 100% of all snakes, including 611 breach attempts by 65 individuals. Mini chain link mesh (7 × 9 mm aperture, 1 mm dia. wire) repelled 100% of all snakes, including 1053 breach attempts by 97 individuals. Brown treesnakes were unable to climb either of the two woven wire designs (1642 breach attempts by 171 individuals), making the rolled hood serve as a redundant secondary snake barrier. The rolled hood repelled 100% of all snakes when individuals were provided a climbable surface to access the hood (94 breach attempts by 39 snakes). The probability of a snake being able to climb the mini chain link mesh was inversely related to snout-vent length. The rolled hood repelled 100% of all rats, with 5080 breach attempts by 21 individuals. Recommended next steps include consultation with engineers to address wind loading, structural integrity, material interactions, and integration of decision-support tools to optimize cost and efficacy of barrier designs on the landscape.