Termite presence and feeding on loblolly pine wood differs among four root-infecting bluestain (ophiostomatoid) fungal species

Authors: CLAY, NATALIE - Louisiana Technical University; SIEGERT, COURTNEY` - Mississippi State University; Tang, Juliet; Little, Nathan; ECKHARDT, LORI - Auburn University; RIGGINS, JOHN - Mississippi State University

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2021
Publication Date: 6/16/2021
Citation: Clay, N.A., Siegert, C., Tang, J.D., Little, N., Eckhardt, L.G., Riggins, J.J. 2021. Termite presence and feeding on loblolly pine wood differs among four root-infecting bluestain (ophiostomatoid) fungal species. Environmental Entomology. https://doi.org/10.1093/ee/nvab052.
DOI: https://doi.org/10.1093/ee/nvab052

Interpretive Summary: This study investigates multitrophic interactions between bark beetles, their associated fungi, and subterranean termites on a landscape scale. We evaluated a large sample size of pine roots across the southern U.S., with and without certain ophiostomatoid fungi, to determine subterranean termite preference and the impetus for this behavior. These field evaluations were also paired with laboratory choice assays to determine preference for certain species of fungi that are vectored by bark- and root-weevils. Data from this study indicates that multitrophic interactions between bark beetle and root weevil attacked trees, bluestain fungi, and subterranean termites may span above- and below-ground boundaries to influence nutrient cycling and likely subsequent decomposer community structure.

Technical Abstract: Insect pests can have large impacts on forest ecosystems. Bark beetles and root weevils can both cause tree death on landscape scales, but may also have indirect effects on belowground processes like decomposition of beetle-attacked wood and the associated decomposer communities. Recently, subterranean termite activity has been linked to bark and root beetle activity mediated through the presence of bluestain fungi (Ascomycota: Ophiostomacea), which are vectored to trees by beetles. However, most of the research has focused on a small subset of bluestain species. Here we test whether termite association patterns in the field on tree roots with or without bluestain fungi reflect termite feeding preference in laboratory choice trials. We documented the presence of four bluestain fungi (Leptographium procerum, L. terebrantis, Grosmannia huntii, and G. alacris) in the roots of 2350 loblolly pine trees in the southeastern US and whether termites were present or absent on these roots. We paired this with laboratory choice trials. Termites were more likely to be found on tree roots that had at least one of these bluestain fungi present than tree roots without any bluestain fungi. Although termites in this study and others were associated with L. procerum, L. terebrantis, and marginally G. huntii, termites only showed preferential feeding on wood inoculated with G. huntii in laboratory trials. This suggests that increased termite presence on wood inoculated with bluestain fungi may be driven by a factor other than increased wood palatability. However, differential distribution of termites can affect wood turnover rates for specific pools (e.g., bark and root beetle attacked trees) and in some cases (e.g., G. huntii) accelerate coarse woody debris decomposition. This study builds upon the growing evidence that the association between subterranean termites and bluestain fungi is spatially and taxonomically widespread.