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Villari Forest Pathology Lab

Caterina and Zack take bark samples

Welcome! Our lab is interested in understanding the interactions among trees, fungal pathogens and insect herbivores, with particular attention to chemical ecological aspects.

Part of our work focuses on symbioses between bark beetles and Ophiostomatoid fungi, and on tree defense mechanisms, driven by the curiosity to understand the role of associated fungi in bark beetle establishment in the host. We are also interested in how abiotic disturbances influence the pathogen/host interaction. Finally, we use cutting-edge molecular techniques to detect invasive species directly in the field.


Leptographium complex

Leptographium-innoculated pineWe study Leptographium and Grosmannia species associated with root-feeding beetles in the southeastern forests. Our research objectives are to elucidate the fungal species carried by native and exotic root-feeding beetles in healthy and unhealthy pine stands, to determine the pathogenicity of the different Leptographium species, and to analyze the host response to colonization by the fungi.

This project is a collaboration with Dr. Gandhi (Forest Entomologist at Warnell, UGA) and Dr. Klepzig (Jones Ecological Research Center).


Laurel wilt disease diagnosis

Caterina inoculating a tree with laurel wiltWe are developing and validating a LAMP (loop mediated isothermal amplification) based assay for the rapid, in-field, early detection and identification of the causal agent of laurel wilt disease (LWD). Laurel wilt is a devastating disease which is decimating redbay and threatening other lauraceous species, including sassafras throughout the eastern USA, California bay on West Coast and commercial avocado. The disease is caused by Raffaelea lauricola, an invasive fungal pathogen vectored by the redbay ambrosia beetle. Early detection and rapid sanitation of infected plants are crucial steps to slow disease spread, and critical components of an integrated pest management program.

LAMP is an innovative molecular technology that meets all the major technical and economic requirements for successful in-field implementation by non-technical users, and has been already optimized for the detection of tree pathogens using portable devices (e.g., sudden oak death and ash dieback). In addition, despite being performed in few simple steps, LAMP is highly sensitive, and potentially able to detect the pathogen even in asymptomatic tissues, or directly on the insect vectors. Trained forest health monitoring personnel, equipped with portable devices, will be able to confirm the diagnosis of LWD in both symptomatic and asymptomatic samples, or identify a potential insect vector, in as short as 30 minutes, without having to rely on traditional, costly, time-consuming laboratory procedures.

This project is a collaboration with Dr. Fraedrich (USDA Forest Service), and is funded by the USDA Forest Service Special Technology Development Program.


Little leaf disease

Phytophthora on a chestnut rootThis study is part of a bigger project aimed at identifying the drivers of the recent Ips avulsus beetle outbreak on the Oconee Ranger District. The pathology component of the project is looking at the incidence of Phytophthora cinnamomi, a root pathogen which causes littleleaf disease on pine trees. The presence/absence of P. cinnamomi  is assessed via isolation on selective media from soil and root samples, followed by molecular confirmation of the pathogen identity. Phytophthora species other than P. cinnamomi are also monitored.

This project is a collaboration with Dr. Gandhi, Dr. Morris (Forest Entomologist at Warnell, UGA), and Ms. Beard (USDA Forest Service), and is funded by the USDA FS Chattahoochee-Oconee National Forest.


Sugarberry decline and mortality

Sugarberry or southern hackberry (Celtis laevigata) is a medium size tree that is common in many forest types throughout the southeastern USA. A decline and mortality of the species has been recently observed in both forest and urban areas of South Carolina and Georgia, but causes of the disease are not understood. Trees affected by the disease exhibit an array of symptoms including leaf chlorosis, development of smaller than normal foliage, early leaf drop/thinning crowns, and a progressive crown dieback which occurs over one to several years. The stems and roots of affected trees develop a brownish discoloration in the phloem early in the disease cycle, and the discoloration appears to spread throughout the phloem as trees succumb to the disease. A number of insect pests and potential pathogens have been associated with the decline, however, at this time most of these appear to be secondary opportunistic organisms rather than primary causal agents.

Phytoplasmas, viruses and bacteria, including fastidious bacteria, have all been associated with various types of decline and are notoriously difficult to diagnose and not readily identified in symptomatic trees without using molecular approaches. The objective of this project study is to determine if and what types of bacteria and phytoplasmas are associated with the phloem of declining sugarberries by using a metabarcoding approach, with the overarching goal of moving forward with the understanding of the causal agent(s) of the sugarberry decline.

This project is a collaboration with Drs. Cram, Fraedrich, Olatinwo and Ulyshen (USDA Forest Service), and is funded by the USDA FS Special Technology Development Program and the USDA FS Southern Research Station.


Book chapters (peer reviewed)

Hofstetter R.W., Klepzig K.D., Villari, C., 2021. Effects of rising temperatures on ectosymbiotic communities associated with bark and ambrosia beetles. In Bark Beetle Management, Ecology, and Climate Change (pp. 303-341). Academic Press


Journal articles (peer reviewed)

Download the full list.

Hadziabdic D., Bonello P., Hamelin R., Juzwik J., Moltzan B., Rizzo D., Stewart J., Villari C., 2021. The future of forest pathology in North America. Front. Frontiers in Forests and Global Change 4:737445.

Aglietti C., Meinecke C.D., Ghelardini L., Barnes I., van der Nest A., Villari C., 2021. Rapid detection of pine pathogens Lecanosticta acicolaDothistroma pini and septosporum on needles by probe-based LAMP assays. Forests 12:479.

Longleaf pine at The Jones CenterHamilton J.L., Fraedrich S.W., Nairn C.J., Mayfield A.E., Villari C., 2021. A field-portable diagnostic approach confirms laurel wilt disease diagnosis in minutes instead of days. Arboriculture & Urban Forestry 47:98-109.

McNichol B.H., Sullivan B., Munro, H., Montes C.R., Nowak J.T., Villari C., Gandhi K.J.T. 2021. Density-dependent variability in an eruptive bark beetle and its value in predicting outbreaks. Ecosphere 12:e03336.

Pandit K., Smith J., Quesada T., Villari C., Johnson D., 2020. Association of recent incidence of foliar disease in pine species in the southeastern United States with tree and climate variables. Forests 11:1155. doi:10.3390/f11111155

Hamilton J.L., Workman J.N., Nairn C.J., Fraedrich S.W., Villari C., 2020. Rapid detection of Raffaelea lauricola directly from host plant and beetle vector tissues using loop-mediated isothermal amplification. Plant Disease doi:10.1094/PDIS-02-20-0422-RE.

Hulcr J., Barnes I., De Beer Z.W., Duong T.A., Gazis R., Johnson A.J., Jusino M.A., Kasson M.T., Li, Y., Lynch S., Mayers C., Musvuugwa T., Roets F., Seltmamm K.C., Six D., Vanderpool D., Villari C. Bark beetle mycobiome: collaboratively defined research priorities on a widespread insect-fungus symbiosis. Symbiosis 81:101-113. doi:10.1007/s13199-020-00686-9

Munro H.L., Gandhi K.J.K., Barnes B.F., Montes C.R., Nowak J.T., Shepherd W.P., Villari C., Sullivan B.T, 2020. Electrophysiological and behavioral responses Dendroctonus frontalis and terebrans (Coleoptera: Curculionidae) to resin odors of host pines (Pinus spp.). Chemoecology doi:10.1007/s00049-020-00311-7.

Bonello P., Campbell F.T., Cipollini D., Conrad A.O., Farinas C., Gandhi K.J.K., Hain F.P., Parry D., Showalter D.N., Villari C., Wallin K.F., Invasive Tree Pests Devastate Ecosystems—A Proposed New Response Framework. Frontiers in Forests and Global Change 3:2. doi:

Conrad A., Villari C., Sherwood P., Bonello P., 2020. Phenotyping Austrian pine for resistance using Fourier-transform infrared spectroscopy. Arboriculture & Urban Forestry 46:276-286

Munro, H. L., Sullivan, B. T., Villari, C., Gandhi, K. J. K. 2019. A review of the ecology and management of black turpentine beetle (Coleoptera: Curculionidae). Environmental Entomology 48:765-783 doi:10.1093/ee/nvz050

McNichol, B. H., Montes, C. R., Barnes, B. F., Nowak, J. T., Villari, C., Gandhi, K. J. K. 2019. Interactions between southern Ips bark beetle outbreaks, prescribed fire, and loblolly pine (Pinus taeda L.) mortality. Forest Ecology and Management 446:164-174 doi:10.1016/j.foreco.2019.05.036

Lopez-Goldar, X., Villari, C., Bonello, P., Borg-Karlson, A. K., Grivet, D., Sampedro, L., Zas, R. 2019. Genetic variation in the constitutive defensive metabolome and its inducibility are geographically structured and largely determined by demographic processes in maritime pine. Journal of Ecology 107: 2464-2477 doi:10.1111/1365-2745.13159

Mayfiled A.E., Villari. C., Hamilton J.L., Slye J., Langston W., Oten K., Fraedrich S. 2019. First Report of Laurel Wilt Disease caused by Raffaelea lauricola on Sassafras in North Carolina. Plant Disease 103:155 doi:10.1094/PDIS-05-18-0871-PDN

Rigsby C.M., Villari C., Peterson D.L., Herms D.A., Bonello P., Cipollini D. 2019. Girdling increases survival and growth of emerald ash borer larvae on Manchurian ash. Agricultural and Forest Entomology 21:130-135. doi:

Lopez-Goldar X., Villari C., Bonello P., Borg-Karlson A.K., Grivet D., Zas R., Sampedro L. 2018. Inducibility of plant secondary metabolites in the stem predicts genetic variation in resistance against a key insect herbivore in maritime pine. Frontiers in Plant Science doi:

Villari C., Dowkiw A., Enderle R., Ghasemkhani M., Kirisits T., Kjaer E., Marčiulynienė D., McKinney L., Metzler B., Muñoz F., Rostgaard Nielsen L., Pliūra A., Stener L-G, Suchockas V., Rodriguez-Saona L., Bonello P., Cleary M. 2018. Advanced spectroscopy-based phenotyping offers a potential solution to the ash dieback epidemic. Scientific Reports 8:17448 doi:

Mason C.J., Keefover-Ring K., Villari C., Klutsch J.G., Cook S., Bonello P., Erbilgin N., Raffa K.F., Townsend P.A. 2018. Anatomical defenses against bark beetles relate to degree of historical exposure between species and are allocated independently of chemical defenses within trees. Plant, Cell and Environment doi: doi:10.1111/pce.13449

Showalter D.N., Villari C., Herms D.A., Bonello P., 2018. Drought stress increased survival and development of emerald ash borer larvae on coevolved Manchurian ash and implicates phloem-based traits in resistance. Agricultural and Forest Entomology 20:170-179. doi:10.1111/afe.12240


Extension Publications

Ulyshen, M., Fraedrich, S., Cram, M., Horn, S., Villari, C., Niyas, A., Poole, E. 2019. Pest Alert – Sugarberry dieback and mortality. USDA – Forest Service – R8–PR–02–19

Gandhi, K., Klepzig, K., Barnes, B., Gochnour, B., Mccarty, E., Sheehan, T., Villari C., Vogt, J. T. 2019. Bark and woodboring beetles in wind-damaged pine stands in the southern United States. Warnell School of Forestry and Natural Resources – WSFNR 19-38.

Mccarty, E., Cassidy, V., Gandhi, K., & Villari, C. 2019. Nantucket pine tip moth: An insect pest of young pine stands. Warnell School of Forestry and Natural Resources – WSFNR 19-34.

Research Areas:


Research Professional II
Associate Professor, Forest Pathology, Co-director, Southern Pine Health Research Cooperative

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