Human-mediated dispersal drives the spread of the spotted lanternfly (Lycorma delicatula)

Abstract

The spotted lanternfly (Lycorma delicatula) is a novel invasive insect from Asia now established and spreading throughout the United States. This species is of particular concern given its ability to decimate important crops such as grapes, fruit trees, as well as native hardwood trees. Since its initial detection in Berks County, Pennsylvania in 2014, spotted lanternfly infestations have been detected in 130 counties (87 under quarantine) within Connecticut, Delaware, Indiana, Maryland, New Jersey, New York, Ohio, Virginia, and West Virginia. Compounding this invasion is the associated proliferation and widespread distribution of the spotted lanternfly’s preferred host plant, the tree-of-heaven (Ailanthus altissima). While alternate host plant species have been observed, the tree-of-heaven which thrives in disturbed and human-dominated areas (e.g., along roads and railways) is likely facilitating the population growth rates of spotted lanternfly. We simulated the population and spread dynamics of the spotted lanternfly throughout the mid-Atlantic USA to help determine areas of risk and inform continued monitoring and control efforts. We tested the prediction that spotted lanternfly spread is driven by human-mediated dispersal using agent-based models that incorporated information on its life-history traits, habitat suitability, and movement and natural dispersal behavior. Overwhelmingly, our results suggest that human-mediated dispersal (e.g., cars, trucks, and trains) is driving the observed spread dynamics and distribution of the spotted lanternfly throughout the eastern USA. Our findings should encourage future surveys to focus on human-mediated dispersal of egg masses and adult spotted lanternflies (e.g., attachment to car or transported substrates) to better monitor and control this economically and ecologically important invasive species.

Evaluating spotted lanternfly (Hemiptera: Fulgoridae) infestation in the Northern Ohio Valley

“…The G1 findings in 2021–2022 align with previous train-mediated SLF dispersal projections (Jones et al 2022, Ladin et al 2023). The findings on the university S4 site, however, do not align well with train-mediated dispersal, due to its 1.25 km distance from the nearest rail-line, exceeding the expected unaided dispersal range of the SLF (Wolfin et al 2019).…”

“…This suggests that the SLF at S4 likely dispersed to this woodlot by other means. This dispersal may have been aided by personal vehicles (as previously predicted; Jones et al 2022, Ladin et al 2023), as a number of out of state employees commute regularly to the university campus, including from quarantined Pennsylvania counties. However, S4 is relatively far away from campus commuter lots, and a number of survey sites adjacent to staff parking spaces on the campus (e.g., S1, S2, and S3) each had 0 SLF recordings across both sampling years despite the comparable density of preferred hosts.…”

“…It is currently believed that the rapid spread of SLF throughout the United States has been primarily mediated by the transportation of trains, vehicles, and products (Barringer et al 2015, Kim et al 2021, Ladin et al 2023). SLF have been observed to lay egg masses on non-host substrates, including motor vehicles, train cars, and building materials (Urban 2019), so it is of no surprise that most documented human-facilitated long-distance dispersal events are associated with females ovipositing on such surfaces that are then moved before the eggs hatch, sometimes transporting SLF eggs across state lines.…”

Assessing acceptability of wild and cultivated hosts of Lycorma delicatula (Hemiptera: Fulgoridae) under semifield conditions

“…Data from field trap captures have shown that L. delicatula are consistently present on J. nigra throughout the insect's development, but adults are in much lower numbers than nymphs when compared with A. altissima (Nixon et al 2023a). As studies have shown, L. delicatula can complete their development and reproduce in field cages containing the hardwood trees S. babylonica, A. saccharinum , and B. nigra (Uyi et al 2020, 2021); the suitability of these common wild hosts, including J. nigra , allows for greater spread and establishment of L. delicatula throughout the Eastern United States than can be predicted by assuming establishment only occurs when A. altissima is present (Ladin et al 2023). While certain deciduous hardwoods and woody ornamentals have been shown to be less suitable for L. delicatula , we do not know the reason.…”

“…Suitability of both wild and cultivated host plants, combined with emerging information on temperature limits and L. delicatula diapause (Keena and Nielsen 2021, Kreitman et al 2021, Nixon et al 2022a), can be used to inform predictive models on the spread of this invasive species (Jung et al 2017, Wakie et al 2020, Huron et al 2022). However, with the capacity for human-assisted transport (Ladin et al 2023) and the prevalence of A. altissima across the United States, eradication will continue to be difficult (Urban and Leach 2023). Spread and establishment can be slowed by concentrating management efforts on key hosts such as A. altissima , J. nigra , and V. vinifera .…”