Deciphering the vectors: unveiling the local dispersal of Litylenchus crenatae ssp. mccannii in the American beech (Fagus grandifolia) forest ecosystem

Authors: GORAYA, MANKANWAL - Pennsylvania State University; KANTOR, CAMELIA - Pennsylvania State University; Vieira, Paulo; Martin, Danielle; KANTOR, MIHAIL - Pennsylvania State University

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2024
Publication Date: 11/8/2024
Citation: Goraya, M., Kantor, C., Reis Vieira, P.C., Martin, D.K., Kantor, M. 2024. Deciphering the vectors: unveiling the local dispersal of Litylenchus crenatae ssp. mccannii in the American beech (Fagus grandifolia) forest ecosystem. PLOS ONE. https://doi.org/10.1371/journal.pone.0311830.
DOI: https://doi.org/10.1371/journal.pone.0311830

Interpretive Summary: Beech trees (Fagus spp.) are an important species of hardwood tree that have great ecological significance worldwide. Throughout North America, the American beech is facing a major threat from the lethal beech leaf disease (BLD). The causal agent of BLD is Litylenchus crenatae ssp. mccannii (Lcm), a recently described nematode, that affects the leaves and buds of beech trees. However, the dispersal mechanisms have remained largely unknown. Therefore, the primary aim of this study was to discover how this nematode moves from tree to tree. We observed how environmental conditions such as wind and humidity can impact dispersal and explored the impact of various organisms commonly found in the American beech forest ecosystems. Our data indicate that multiple factors can significantly impact the dispersal of the nematodes. The insights gained by this study not only enhance our understanding of Lcm local scale dispersal patterns but also lay a foundation for predicting its potential long-range dispersion. This information also provides valuable insights for the a development of effective BLD management strategies.

Technical Abstract: Beech leaf disease (BLD), caused by the Litylenchus crenatae ssp. mccannii (Lcm) nematode, is an emerging threat to beech trees. This disease is characterized by distinct leaf symptoms, including leaf interveinal banding and thickened leaf texture, which leads to eventual tree mortality. Understanding Lcm dispersal mechanism(s) is crucial for managing BLD, yet these remain largely unknown, posing a major barrier to effective management. This study represents a pioneering investigation into the abiotic and biotic vectors that potentially contribute to the local dispersal of Lcm in natural American beech (Fagus grandifolia) forest systems in the Northeastern United States. An experiment was set up in Stone Valley Forest, Pennsylvania (PA), using four funnel stands placed at variable distances from naturally BLD-infected beech trees. This approach enabled the recovery of active Lcm nematodes from each funnel, demonstrating their ability to naturally disperse at least 11.74 m from the nearest BLD-infected tree. The findings highlight the role of abiotic factors involved in the dispersal dynamics of Lcm, especially wind and humidity, as indicated by a generalized linear model. The current study also uncovered the incidental association of Lcm with other organisms beneath the canopy of BLD trees, including spiderwebs and caterpillars. To our knowledge, this is the first study to document the potential vectors involved in the local dispersal of Lcm, offering valuable information for the biology of this nematode, as well as insight for the development of effective BLD management strategies. The findings contribute to broader efforts in advancing the understanding of the local spread of BLD, highlighting the complex interplay of abiotic and biotic factors in this disease dispersal.