Location: Southern Insect Management ResearchTitle: Inoculation of ophiostomatoid fungi in Loblolly pine trees increases the presence of subterranean termites in fungal lesions
|CLAY, NATALIE - Mississippi State University|
|RIGGINS, JOHN - Mississippi State University|
Submitted to: Arthropod-Plant Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2016
Publication Date: 12/26/2016
Citation: Clay, N.A., Little, N., Riggins, J.J. 2016. Inoculation of ophiostomatoid fungi in Loblolly pine trees increases the presence of subterranean termites in fungal lesions. Arthropod-Plant Interactions. 16(3):260-264. doi:10.1111/afe.12053.
Interpretive Summary: In several previously published manuscripts (see references Little et al. 2012a, 2012b, 2013 and Riggins et al. 2014 in the submission), we demonstrated that subterranean termites located and preferentially fed on wood containing blue-stain fungi compared to unstained wood. In this study, we tested whether these same behavioral patterns occur at the scale of whole trees in natural settings. We inoculated 72 healthy loblolly pine trees with one of six bark beetle fungal associates: Ophiostoma minus, O. ips, Leptographium terebrantis, L. procerum, O. minus + L. terebrantis (combo), or sterilized, distilled H2O as a control. Trees inoculated with blue-stain fungi had higher instances of subterranean termites around injection sites than controls; however, there was no difference among fungal treatments. This previously unknown ecological link between bark beetles and subterranean termites could aid in our understanding of accelerated tree death, fall, and decay, which impact forest biogeochemistry, hydrology, and succession.
Technical Abstract: Bluestain (ophiostomatoid) fungi are vectored to trees via bark beetle activity, but their ecological roles are not fully understood. Hypotheses range from fungi as harmless hitchhikers to integral mutualists aiding beetles in overwhelming tree defenses. Recently, correlational field studies and small-scale laboratory feeding trials have demonstrated a positive link between bluestain fungi and subterranean termites, but experimental field evidence for this novel connection is lacking. To test the hypotheses that bluestain fungi 1) can cause pine tree mortality, and 2) increase termite presence in infected trees, we inoculated 72 loblolly pine trees in the southeastern USA with one of four bluestain fungi (Ophiostoma minus, O. ips, Leptographium terebrantis, L. procerum), a combination (O. minus + L. terebrantis), or distilled H2O as a control. Over four years, we found no tree mortality, and all fungi-inoculated trees formed lesions around injection sites, while control trees formed no lesions. Lesion size generally increased over time, but was relatively consistent among treatments. Bluestain inoculated trees had increased termite presence regardless of fungal treatment. Thus, it is unlikely the bluestain fungi we examined directly cause mortality in loblolly pine healthy trees, but increased termite presence could impact wood decomposition dynamics.