Radio Telemetry and Harmonic Radar Tracking of the Spotted Lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae)

Simple Summary The spotted lanternfly is an invasive insect that damages a number of economically important plants and is a nuisance pest for residents and businesses. An improved understanding of spotted lanternfly movement may lead to better control methods for this pest that help slow its spread. To better understand spotted lanternfly movements, two types of tracking technologies were tested: radio telemetry and harmonic radar. A tag was attached to each spotted lanternfly which was then released into the wild and tracked. Both the adults and fourth-instar nymphs were tracked during the course of this study. More than half of the tracked adults remained sedentary or moved less than 5 m, whereas active adults moved up to 434 m, averaging under 20 m per 1–3 d period, and activity patterns varied by sex and adult stage. The longest distances were moved by females between the first field observation of mating and two weeks after the first fresh egg mass was found, and male movements continued increasing for an additional two weeks. SLF height in trees at the beginning of a movement was significantly and positively related to the distance of the subsequent movement. Most adults were found 6–9 m high in trees. During mating time, tracked SLF were significantly higher than 8 m and oriented to trees where tight aggregations of SLF already occurred. Tracked nymphs were found to walk almost 30 m over a five-day period. Abstract Lycorma delicatula (White) (Hemiptera: Fulgoridae), spotted lanternfly (SLF), is an invasive pest that feeds and oviposits on numerous woody and herbaceous plants important to agricultural, forest, ornamental, and nursery industries. Describing and understanding SLF movements is key to implementing surveillance and control strategies for this pest and projecting population spread. We used radio telemetry (RT) and harmonic radar (HR) to track the movements of individual SLF at field sites in eastern Pennsylvania and northwestern New Jersey. SLF equipped with HR or RT tags were tracked in 2019 and 2020 from adult emergence until oviposition time, and their movements are described. Although the bulkier RT tags disproportionately affected the distance traveled by males, which are smaller than females, both males and females were more likely to be lost due to signal attenuation when affixed with the lighter-weight HR tags. Females were tracked moving longer distances than males, with maximum distances of 434 m by a single female and 57 m by a single male. A significant positive relationship was found between their height in trees and the distance of subsequent movement. Adult SLF were found in trees predominantly at heights between 6–9 m high. For the fraction of SLF found at eye level, males, but not females, significantly moved above eye level in the weeks prior to mating, likely resulting in the observed sex ratio shift that defines the Early-2 stage. During mating time, tracked SLF were significantly higher than 8 m and oriented to trees where tight aggregations of SLF were present. This orientation towards tight aggregations started when mating began and peaked in the following 2.5 weeks for males in Late-1 and the beginning of Late-2 (after oviposition began), whereas females started this orientation behavior a half-week after males, and this activity peaked for two weeks. Male and female SLF adults exhibited slight differences in host preference, and strong preferences for wild grape, black walnut, sweet birch, and tree-of-heaven were observed. The HR-tagged nymphs moved up to 27.6 m over a five-day period in a cornfield. Nitinol wire HR tags performed better than Wollaston process or tungsten wire tags. SLF movement parameters in the field are described.