Tracking the invasive hornet Vespa velutina in complex environments by means of a harmonic radar

Abstract

An innovative scanning harmonic radar has been recently developed for tracking insects in complex landscapes. This movable technology has been tested on an invasive hornet species (Vespa velutina) for detecting the position of their nests in the environment, in the framework of an early detection strategy. The new model of harmonic radar proved to be effective in tracking hornets either in open landscapes, hilly environments and areas characterised by the presence of more obstacles, such as woodlands and urban areas. Hornets were effectively tracked in complex landscapes for a mean tracking length of 96 ± 62 m with maximum values of ~ 300 m. The effectiveness of locating nests was 75% in new invasive outbreaks and 60% in highly density colonised areas. Furthermore, this technology could provide information on several aspects of insect’s ecology and biology. In this case, new insights were obtained about the mean foraging range of V. velutina (395 ± 208 m with a maximum value of 786 m) and flying features (ground speed), which was 6.66 ± 2.31 m s−1 for foraging individuals (hornets that are not carrying prey’s pellet) and 4.06 ± 1.34 m s−1 for homing individuals.

Pollinator nutrition and its role in merging the dual objectives of pollinator health and optimal crop production

“…Unmanned aerial vehicle mapping of vegetation [ 120 ] and harmonic radar tracking techniques to monitor pollinator movements are now available [ 121 ] and may enable high accuracy modelling of the spatial and temporal variations in pollinator activity and resource availability around crop sites. When combined with sensitive chemical analytical techniques to determine the chemical profiles of pollen and nectar [ 122 ], these technologies may enable more accurate estimation of the quality and distribution of floral resources around farms, which is essential information for field-based studies on habitat enhancement.…”

The Asian wasp Vespa velutina nigrithorax: Entomological and allergological characteristics

“…In addition, the attractant employed and the season can affect the traps' effectiveness, making it more difficult to combat this species without damaging other species. 26,27 New technologies,…”

“…Sugar‐based traps have been widely used for attracting social wasps, V. velutina among them; however, the main problem with such traps is that they also trap other species and have a negative impact on native species. In addition, the attractant employed and the season can affect the traps’ effectiveness, making it more difficult to combat this species without damaging other species 26,27 . New technologies, such as exposure to heat, are being implemented to destroy V. velutina nests.…”

“…Steam injection could therefore be a promising technique for destroying these nests, given its effectiveness and eco‐friendliness 25 . An innovative scanning harmonic radar has been employed in Italy to track the flight of V. velutina , 27 a technique that appears to be effective in detecting V. velutina nests in open terrain; however, it does not help to detect nests in highly urbanized areas, woodland landscapes or areas with steep slopes 27 . In general, the early detection of V. velutina nests is essential due to the nearly impossible task of removing the pest in those countries with widespread and uncontrolled colonization by the wasp.…”

“…20,23 The ecological and economic implications of the invasion by V. velutina have prompted campaigns to reduce its population and its negative effects in several countries of the European Union. 19,[24][25][26][27] Certain measures have proven successful, such as the policies developed in Great Britain where nests have been rapidly identified thanks to the efforts of the National Bee Unit and Asian Hornet Action Teams, 24 an organization responsible for euthanizing detected nests and making them nonviable, so that adult wasps can no longer live there. 24 Similarly, a strategy based on combining various eradication methods (such as trapping, citizen-collected scientific data for detecting the nests and the active search for nests, followed by their removal using mechanical methods) has been tested in the Baleares archipelago in the Mediterranean and found to be successful; the last Asian wasp found there was in June 2018.…”