Dr Jeff Garnas

Senior Lecturer


Zoology and Entomology
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Ecology and evolution of insects and microbes on native and exotic trees

I am a ecologist, entomologist and evolutionary biologist focused on questions related to insects and fungi that interact with plants, primarily forest trees. I use a variety of approaches and tools, including observational studies, field and lab experiments, modeling and molecular analyses to test hypotheses and search for strong inference in the systems I study. I approach ecological and evolutionary questions using a strong theoretical framework while producing and communicating products that will have applied value to conservation and to land and forest managers. In particular, I am interested in drivers of host use and community overlap among native and exotic tree species, patterns of population genetic diversity in native and introduced insects and fungi, and the role of complex interactions in driving forest insect population and community dynamics.

Increasingly, my work sits at the interface between field ecology and ecological and evolutionary genetics and genomics. I am particularly interested in understanding the patterns and consequences of global invasion of insects and microbes linked to the intentional cultivation of exotic trees, which inevitably results in the creation of novel ecosystems. 

Reconstructing pathways of global spread in the red gum lerp psyllid (Glycaspis brimblecombei) using bacterial endosymbiont genomes and insect population diversity

Determinants of host use and community overlap among insects feeding on African and Australian acacias in South Africa

Implications of cryptic diversity in the Eucalyptus snout beetle (Gonipterus spp.) on the ecology, host plant use and effectiveness of biological control by an egg parasitic wasp (Anaphes nitens)

Population dynamics of invasive European woodwasp (Sirex noctilio) as driven by abiotic variability and community interactions in the larval environment

Endophytic fungal diversity in native and introduced tree hosts (using 454 and Illumina sequencing technology)

Biology, host use and microbial associates of a native wood-boring moth (Coryphodema tristis) on native and exotic trees

Insect and pathogen biodiversity on native pine, with particular focus on native bark beetle-Ophiostomatoid fungi interactions in Central America

ZEN351:  Population Ecology (3rd-year Zoology/Entomology course)

ZEN782:  Plant-Insect Interactions (Honours module; discussion and project-based)

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Book Chapters
Garnas JR, Hurley BP, Slippers B, Wingfield MJ, Roux J. 2016. Insects and Diseases of Mediterranean Forests: A South African Perspective. In: Insects and Diseases of Mediterranean Forest Systems. Paine TD, Lieutier F. (eds). Springer International Publishing, Switzerland, pp 397-430.
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Morrison EW, Duong TA, Garnas JR. (2024) A high-quality draft genome sequence of Neonectria faginata, causative agent of beech bark disease of Fagus grandifolia. Microbiology Resource Announcements 10.1128/mra.01048-23
Fitza KNE, Garnas JR, Slippers B. (2022) Experimental admixture among distinct lineages of Deladenus siricidicola, the biocontrol agent of Sirex noctilio. Biological Control 10.1016/j.biocontrol.2022.104875
Dittrich-Schröder G, Garnas JR, Arriagades-Cares D, Ahumada R, Hurley BP, Lawson SA, Slippers B. (2021) Diversity and Introduction History of Glycaspis brimblecombei Reflects a History of Bridgeheads and Distinct Invasions. Frontiers in Forests and Global Change 4:1-11. 10.3389/ffgc.2021.783603
Krivak-Tetley FE, Lantschner MV, Lombardero MJ, Garnas JR, Hurley BP, Villacide JM, Slippers B, Corley J, Liebhold AM, Ayers MP. (2020) Aggressive tree killer or natural thinning agent? Assessing the impacts of a globally important forest insect. Forest Ecology and Management 10.1016/j.foreco.2020.118728
Garnas JR, Vann KE, Hurley BP. (2020) Biotic and abiotic effects on density, body size, sex ratio, and survival in immature stages of the European woodwasp, Sirex noctilio. Ecology and Evolution 10.1002/ece3.6966 PDF
Mutitu E, TB Hoareau, Hurley BP, Garnas JR, Wingfield MJ, Slippers B. (2020) Reconstructing early routes of invasion of the bronze bug Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae): cities as bridgeheads for global pest invasions. Biological Invasions 10.1007/s10530-020-02258-w
Queffelec J, Wooding AL, Greef JM, Garnas JR, Hurley BP, Wingfield MJ, Slippers B. (2019) Mechanisms that influence sex ratio variation in the invasive hymenopteran Sirex noctilio in South Africa. Ecology and Evolution :1-8. 10.5061/dryad.f3p8j8g PDF
Wondafrash M, Slippers B, Hurley BP, Garnas J. (2019) Local antagonism and resource partitioning between two invasive pine plantation pests. Agricultural and Forest Entomology 10.1111/afe.12330 PDF
Fitza KNE, Garnas JR, Lombardero MJ, Ayres MP, Krivak-Tetley FE, Ahumada R, Hurley BP, Wingfield MJ, Slippers B. (2019) The global diversity of Deladenus siricidicola in native and non-native populations. Biological Control 132:57-65. 10.1016/j.biocontrol.2019.01.014 PDF
Fitza KNE, Garnas JR, Lombardero MJ, Ayres MP, Krivak-Tetley FE, Ahumada R, Hurley BP, Wingfield MJ, Slippers B. (2019) The global diversity of Deladenus siricidicola in native and non-native populations. Biological Control 132:57-65. https://doi.org/10.1016/j.biocontrol.2019.01.014
Burgess TI, Tan YP, Garnas J, Edwards J, Scarlett KA, Shuttleworth LA, Daniel R, Dann EK, Parkinson LE, Dinh Q, Shivas RG, Jami F. (2019) Current status of the Botryosphaeriaceae in Australia. Australasian Plant Pathology 10.1007/s13313-018-0577-5 PDF
Wondafrash M, Slippers B, Garnas J, Hurley BP. (2017) Parasitoid assemblage associated with a North American pine weevil in South Africa. Agricultural and Forest Entomology 10.1111/afe.12246
Burgess T, White D, McDougall K, Garnas J, Dunstan W, Català S, Carnegie A, Worboys S, Cahill D, Vettraino AM, Stukely M, Liew E, Paap T, Bose T, Migliorini D, Williams B, Brigg F, Crane C, Rudman T, Hardy G. (2017) Phytophthora distribution and diversity across Australia. Pacific Conservation Biology 23(1-13) 10.1071/PC16032
Olivier-Espejel S, Hurley BP, Garnas J. (2017) Assessment of beetle diversity, community composition and potential threats to forestry using kairomone-baited traps. Bulletin of Entomological Research 107(1):106-117. 10.1017/S0007485316000699
Fitza KNE, Tabata M, Kanzaki N, Kimura K, Garnas J, Slippers B. (2016) Host specificity and diversity of Amylostereum associated with Japanese siricids. Fungal Ecology 24(A):76-81. 10.1016/j.funeco.2016.08.005
Wondafrash M, Slippers B, Garnas J, Roux G, Foit J, Langor DW, Hurley BP. (2016) Identification and genetic diversity of two invasive Pissodes spp. Germar (Coleoptera: Curculionidae) in their introduced range in the southern hemisphere. Biological Invasions 18:2283. 10.1007/s10530-016-1159-5
Garnas J, Auger-Rozenberg M, Roques A, Bertelsmeier C, Wingfield MJ, Saccaggi DL, Roy HE, Slippers B. (2016) Complex patterns of global spread in invasive insects: Eco-evolutionary and management consequences. Biological Invasions 18(4):935-952. 10.1007/s10530-016-1082-9 PDF
Hill MP, Bertelsmeier C, Clusella-Trullas S, Garnas J, Robertson MP, Terblanche JS. (2016) Predicted decrease in global climate suitability masks regional complexity of invasive fruit fly species response to climate change. Biological Invasions 18(4):1105-1119. 10.1007/s10530-016-1078-5
Hurley BP, Garnas J, Wingfield MJ, Branco M, Richardson DM, Slippers B. (2016) Increasing numbers and intercontinental spread of invasive insects on eucalypts. Biological Invasions 18(4):921-933. 10.1007/s10530-016-1081-x PDF
Roques A, Auger-Rozenberg M, Blackburn TM, Garnas J, Pyšek P, Rabitsch W, Richardson DM, Wingfield MJ, Liebhold AM, Duncan RP. (2016) Temporal and interspecific variation in rates of spread for insect species invading Europe during the last 200 years. Biological Invasions 18(4):907-920. 10.1007/s10530-016-1080-y PDF
Hui C, Richardson DM, Landi P, Minoarivelo HO, Garnas J, Roy HE. (2016) Defining invasiveness and invasibility in ecological networks. Biological Invasions 18(4):971-983. 10.1007/s10530-016-1076-7
Wingfield MJ, Garnas JR, Hajek A, Hurley BP, de Beer ZW, Taerum SJ. (2016) Novel and co-evolved associations between insects and microorganisms as drivers of forest pestilence. Biological Invasions 18(4):1045-1056. 10.1007/s10530-016-1084-7 PDF
Hajek AE, Hurley BP, Kenis M, Garnas J, Bush SJ, Wingfield MJ, Lenteren JCV, Cock MJW. (2016) Exotic biological control agents: a solution or contribution to arthropod invasions?. Biological Invasions 18(4):953-969. 10.1007/s10530-016-1075-8 PDF
Nadel RL, Wingfield MJ, Scholes MC, Garnas JR, Lawson SA, Slippers B. (2015) Population dynamics of Thaumastocoris peregrinus in Eucalyptus plantations of South Africa. Journal of Pest Science 88:97-106. 10.1007/s10340-014-0558-6 PDF
Hurley BP, Garnas J, Cooperband MF. (2015) Assessing trap and lure effectiveness for the monitoring of Sirex noctilio. Agricultural and Forest Entomology 17(1):64-70. PDF
Garnas J, Groden E, Drummond FA. (2014) Mechanisms of competitive displacement of native ant fauna by invading Myrmica rubra (Hymenoptera: Formicidae) populations. Environmental Entomology 43(6):1496-506. 10.1603/EN14079
Lantschner V, Villacide JM, Garnas JR, Croft P, Carnegie AJ, Liebhold AM, Corley JC. (2014) Temperature explains variable spread rates of the invasive woodwasp Sirex noctilio in the Southern Hemisphere. Biological Invasions 16(2):329-339. 10.1007/s10530-013-0521-0 PDF
Kemler M, Garnas JR, Wingfield MJ, Gryzenhout M, Pillay KA, Slippers B. (2013) Ion Torrent PGM as tool for fungal community analysis: A case study of endophytes in Eucalyptus grandis reveals high taxonomic diversity. PLoS ONE 8(12):e81718. 10.1371/journal.pone.0081718 PDF
Degefu DT, Hurley BP, Garnas JR, Wingfield MJ, Ahumada R, Slippers B. (2013) Parallel host range expansion in two unrelated cossid moths infesting Eucalyptus nitens on two continents. Ecological Entomology 38:112-116. 10.1111/j.1365-2311.2012.01396.x PDF
Garnas JR, Houston DR, Twery MJ, Ayres M, Evans C. (2013) Inferring controls on the epidemiology of beech bark disease from spatial patterning of disease organisms. Agricultural and Forest Entomology 15(2):146-155. 10.1111/j.1461-9563.2012.00595.x
Mutitu EK, Garnas JR, Hurley BP, Wingfield MJ, Harney M, Bush SJ, Slippers B. (2013) Biology and rearing of Cleruchoides noackae (Hymenoptera: Mymaridae), an egg parasitoid for the biological control of Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae). Journal of Economic Entomology 106:1979-1985. 10.1603/EC13135 PDF
Wingfield MJ, Roux J, Slippers B, Hurley BP, Garnas J, Myburg AA, Wingfield BD. (2013) Established and new technologies reduce increasing pest and pathogen threats to Eucalypt plantations. Forest Ecology and Management 301:35-42. 10.1016/j.foreco.2012.09.002 PDF
Wooding AL, Wingfield MJ, Hurley BP, Garnas JR, De Groot P, Slippers B. (2013) Lack of fidelity revealed in an insect-fungal mutualism after invasion. Biology Letters 9(4):1-4. 10.1098/rsbl.2013.0609 PDF
Wooding AL, Wingfield MJ, Hurley BP, Garnas JR, De Groot P, Slippers B. (2013) Lack of fidelity revealed in an insect–fungal mutualism after invasion. Biology letters 9(4):20130342. PDF
Garnas JR, Hurley BP, Slippers B, Wingfield MJ. (2012) Biological control of forest plantation pests in an interconnected world requires greater international focus. International Journal of Pest Management 58:211-223. 10.1080/09670874.2012.698764 PDF
Garnas JR, Houston DR, Ayres MP, Evans C. (2012) Disease ontogeny overshadows effects of climate and species interactions on population dynamics in a nonnative forest disease complex. Ecography 35(5):412-421. 10.1111/j.1600-0587.2011.06938.x
McPhee K, Garnas JR, Drummond F, Groden E. (2012) Homopterans and an invasive red ant, Myrmica rubra (L.), in Maine. Environmental Entomology 41(1):59-71. 10.1603/EN11046
Garnas JR, Ayres MP, Liebhold A, Evans C. (2011) Subcontinental impacts of an invasive tree disease on forest structure and dynamics. Journal of Ecology 99:532-541. 10.1111/j.1365-2745.2010.01791.x
Dukes JS, Pontius J, Orwig D, Garnas JR, Rodgers VL, Brazee N, Cooke B, Theoharides KA, Stange EE, Harrington R, Ehrenfeld J, Gurevitch J, Lerdau M, Stinson K, Wick R, Ayres MP. (2009) Responses of insect pests, pathogens, and invasive plant species to climate change in the forests of northeastern North America: What can we predict?. Canadian Journal of Forest Research 39(2):231-248. 10.1139/X08-171
Garnas JR, Groden E, Drummond FA. (2007) Intercolony aggression within and among local populations of the invasive ant, Myrmica rubra (Hymenoptera: Formicidae), in coastal Maine. 36:105-113.
Groden E, Drummond FA, Garnas JR, Franceour A. (2005) Distribution of an invasive ant, Myrmica rubra (Hymenoptera: Formicidae), in Maine. Journal of Economic Entomology 98(6):1774-1784.