In the wind: Invasive species travel along predictable atmospheric pathways.

Invasive species such as insects, pathogens, and weeds reaching new environments by traveling with the wind, represent unquantified and difficult-to-manage biosecurity threats to human, animal, and plant health in managed and natural ecosystems. Despite the importance of these invasion events, their complexity is reflected by the lack of tools to predict them. Here, we provide the first known evidence showing that the long-distance aerial dispersal of invasive insects and wildfire smoke, a potential carrier of invasive species, is driven by atmospheric pathways known as Lagrangian coherent structures (LCS). An aerobiological modeling system combining LCS modeling with species biology and atmospheric survival has the potential to transform the understanding and prediction of atmospheric invasions. The proposed modeling system run in forecast or hindcast modes can inform high-risk invasion events and invasion source locations, making it possible to locate them early, improving the chances of eradication success.

Light-Weight Portable Electroantennography Device as a Future Field-Based Tool for Applied Chemical Ecology.

Portable electroantennograms (pEAG) can further our understanding of odor plume dynamics and complement laboratory-based electroantennogram tools. pEAG's can help to address important questions such as the influence of plume structure on insect behavior, the active space of semiochemical-baited traps, and the impact of biotic and abiotic factors on this active space. Challenges associated with pEAGs include their miniaturization and sensitivity, confounding environmental odors, and processing of data. Here, we describe a pEAG built with modern engineering hardware and techniques that is portable in being both light in weight (516 g) and smaller (12 × 12 × 8 cm, volume 1152 cm3) than earlier models. It is able to incorporate insects of a range of sizes (4 to 30 mm antennal length), has wireless communication (communication range of 600 m urban, 10 km line of sight), a stand-alone power supply, and uses both antennae of the test insect. We report normalized antennal responses from Epiphyas postvittana in a dose response experiment where our pEAG compared favorably with traditional laboratory EAG equipment for this species. Dose-response comparisons between E. postvittana, Agrotis ipsilon, and Lymantria dispar dispar showed mean detection limits from a pheromone source dose of 100, 100, and 1 ng, respectively, for our pEAG. This pEAG should allow future real-time analysis of EAG responses in the field in research on how insects interact with odor plumes and the factors that influence the active space of semiochemical-baited traps.

Swath pattern analysis from a multi-rotor unmanned aerial vehicle configured for pesticide application.

BACKGROUND: Although unmanned aerial vehicles (UAVs) are increasingly used to deliver small-scale aerial pesticide applications, there remains uncertainty over their efficiency in terms of uniformity of spray deposition and their application efficiency. Consequently, a field study was designed to quantify factors influencing the uniformity of spray deposition from a multi-rotor UAV that is operated commercially in New Zealand. Two sampling systems for measuring spray deposition, a continuous horizontal string and steel plates placed on the ground were compared. RESULTS: The spray deposit distribution characteristics and calculated lane separation values (distance between flight lines that produces a maximum coefficient of variation of 30% for spray deposits) were strongly influenced by wind speed, nozzle position, release height, ground speed and droplet size. Lane separation values ranged from 1 to > 5 m. Swath distribution parameters (spread and position of peak deposition) derived from plates were not significantly different from those derived from string. However, total deposition on strings relative to plates increased with small droplets. Reducing plate sampling intensity from 0.25 m intervals to 0.5 m and even 1.0 m had only a minor effect on estimates of swath parameter values. CONCLUSIONS: The potential for precision spraying from UAV platforms has yet to be achieved with improvements required in hardware and software. Further, mechanistic models are needed to quantify how complex interactions among multiple operating and meteorological variables influence spray deposition. © 2019 Society of Chemical Industry.

Evaluating High Release Rate MCH (3-Methylcyclohex-2-en-1-one) Treatments for Reducing Dendroctonus pseudotsugae (Coleoptera: Curculionidae) Infestations.

Current recommendations for applying the antiaggregation pheromone 3-methylcyclohex-2-en-1-one (MCH) to protect live trees from Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, infestation are to space individual passive releasers (MCH bubble capsules) on a 12- by 12-m grid throughout areas to be protected. Previous field studies and a theoretical study using a puff dispersion model to predict pheromone concentrations have shown that releasers emitting higher rates of MCH spaced farther apart may be as effective as the established standard treatment. During 2012 and 2013, we tested higher release rates of MCH at correspondingly wider spacings to keep the total amount of MCH released per unit area equal in all treatments. In 2012 near Challis, ID, treatments included the established standard release rate and spacing, four and six times the standard release rate at correspondingly wider spacings, and an untreated control. In 2013 near Ketchum, ID, treatments included the established standard release rate and spacing, five and seven times the standard release rate at correspondingly wider spacings, and an untreated control. Results from both years indicated that all MCH treatments were equally effective in reducing Douglas-fir beetle infestation. Using higher release rate formulations at wider spacings will reduce labor costs of installing MCH treatments, and, in cases where it is necessary, retrieving the releasers as well. In addition to reducing labor costs, the revised treatment protocol may increase the feasibility of treating areas that currently may not be possible due to treatment costs.

An aerial spot-spraying technique: a pilot study to test a method for pest eradication in urban environments.

BACKGROUND: Pest eradication strategies that use pesticides require application methods that have the lowest environmental and human health impact while maintaining the highest probability of success. This is highly important when eradication takes place in sensitive areas, such as urban or riparian zones. A new aerial application method, the spot-gun, was developed to provide good pesticide coverage on host species while minimising off-target exposure. This type of targeted aerial approach is useful in areas where conventional broadcast aerial spraying was historically used but was not ideal due to the quantity of pesticide hitting non-host species and going off-target. An even distribution of the active component is essential for eradication. FINDINGS: The spot-gun method was tested and found to provide an even distribution of dye on the adaxial and abaxial leaf surfaces as well as in the top and middle regions in both the inner and outer portions of the canopy. The form of the deposits on the leaf surface was very different from that obtained using a broadcast aerial application with a conventional spray boom. CONCLUSIONS: The distribution results imply that the spot-gun method treatment will provide good efficacy. The implications of the different deposit pattern on efficacy are not known at this stage. This aerial spot-spray method has considerable potential as a tool for targeted aerial application of pesticides to small areas of difficult to reach canopies.

Predicting Dendroctonus pseudotsugae (Coleoptera: Curculionidae) antiaggregation pheromone concentrations using an instantaneous puff dispersion model.

An instantaneous puff dispersion model was used to assess concentration fields of the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, antiaggregation pheromone, 3-methylcyclohex-2-en-1-one (MCH), within a 1-ha circular plot. Several combinations of MCH release rate and releaser spacing were modeled to theoretically analyze optimal deployment strategies. The combinations of MCH release rate and releaser spacing used in the modeling exercise were based on results of previous field studies of treatment efficacy. Analyses of model results suggest that a release rate up to six times the initial standard, at a correspondingly wider spacing to keep the total amount of pheromone dispersed per unit area constant, may be effective at preventing Douglas-fir beetle infestation. The model outputs also provide a visual representation of pheromone dispersion patterns that can occur after deployment of release devices in the field. These results will help researchers and practitioners design more effective deployment strategies.