Emphasis is on pathogens and symbionts of invertebrates, predominantly focusing on interactions between microbes and insect hosts, many of which are invasive species. Subjects covered are broad, ranging from population biology, immune responses, basic biologies of pathogens, interactions between hosts and pathogens and epizootiology to use of microbes for control of insect pests.
Emphasis in the Hajek lab is on pathogens and symbionts of invertebrates, predominantly focusing on interactions between microbes and their arthropod hosts. My interests are broad, ranging from basic biologies of pathogens and symbionts and epizootiology to systematics, population genetics, and immune responses. I have worked extensively with the fungal pathogen, Entomophaga maimaiga, first seen in North America in 1989 and which has been providing natural control of gypsy moth, a major invasive pest of northeastern North American forests for over 100 years. While this Japanese pathogen does not always provide complete control everywhere, it has been maintaining gypsy moth populations in central New York at low densities since it was first reported in North America. In other areas, including some in Pennsylvania (quite near to central New York) gypsy moth outbreaks have continued to occur but with lower levels of defoliation. Our studies have focussed on spatial and temporal variability in activity of E. maimaiga, host specificity population genetics of this fungus, spore dormancy, and persistence of E. maimaiga azygospores in the field and exploring mycoparasitism. Our latest studies include ecological studies of community interactions of pathognes and parasitoids. Our studies with invasive Asian longhorned beetles have been directed toward use of an entomopathogenic fungus for control of this species which was introduced from China. We have developed a novel management approach that provides a means for applying insect pathogenic fungi that remain viable for several months, something previously unheard of. Beetles exposed to the entomopathogenic fungi can vector fungal spores to infect other beetles and they lay fewer eggs before dying. A newer project in the laboratory involves studies of fungal symbionts and a parasitic nematode of the invasive woodwasp Sirex noctilio, first collected from North America in New York State in 2004. Interactions between this new invasive and the poorly known native Sirex species and interchanges of symbionts and parasites among these species is a main focus of present studies. Additional studies in the lab have included the changes in behavior of fungal-infected insects, the effect of host density on susceptibility of gypsy moth caterpillars to virus, and dispersal of gypsy moth pathogens, to name a few. Throughout all of these projects, we strive to learn new information about insect pathogens and symbionts and their relations to hosts that also answers basic and conceptual questions about the ecology and evolution of infection and disease.
The best way for students to learn is to be actively involved in the learning process. Therefore, Dr. Hajek incorporates active learning techniques in her classes whenever possible. She has developed numerous courses during her time at Cornell, including a graduate lecture and lab course on invertebrate pathology, a graduate lecture course on biological control, an undergrad and grad lecture course on invertebrate-microbe interactions that includes demonstration labs and several graduate seminars and a version of this course principally for undergraduates, as well as two different undergraduate non-majors classes (on natural enemies and invasive species). For the undergraduate course on natural enemies, Dr. Hajek wrote a textbook.
At present, every other year Dr. Hajek teaches an interactive course with demonstration laboratories for graduate and undergraduate students on invertebrate-microbe interactions (Entom 4630--Microbe/Invertebrate Associations: Diversity, Ecology & Evolution). She also presently co-teaches a course on invasive species directed toward non-biology majors (Entom 2020--Invasions: Trading Species in a Shrinking World). This interactive course addresses basic ecological principles as well as issues of popular interest about invasive species. The other course she is involved with at present is Entomology/BIOEE 6900--Ecology & Evolution of Infectious Disease. She co-organizes this graduate seminar and gives spring semester sessions. This seminar has been offered for 5 years. See Dr. Hajek's cv for guest lectures in classes at Cornell but also in Denmark, Finland, Japan, and Argentina.Dr. Hajek teaches an interactive graduate course on invertebrate-microbe interactions (Entom 4630--Microbe/Invertebrate Associations: Diversity, Ecology & Evolution). She also co-teaches a course on invasive species predominantly aimed toward non-biology majors (Entom 2020--Invasions: Trading Species in a Shrinking World). In this interactive course basic principles as well as issues of popular interest are presented. Dr. Hajek has also been involved in a graduate level seminar Entomology 6900--Ecology & Evolution of Infectious Disease. This course has been offered for 5 years. See Dr. Hajek’s vita for guest lectures in university classes at Cornell but also for classes taught in Denmark, Finland, Japan, and Argentina.
Awards and Honors
- Honorary Professor in Zoology (2016) Department of Agriculture and Ecology, Faculty of Life Sciences, University of Copenhagen
- L. O. Howard Distinguished Achievement Award (2015) Eastern Branch, Entomological Society of America
- Velux Visiting Professor (2012) University of Copenhagen (supported by the Villum Foundation)
- Distinguished Scientist Award (2011) International Organization of Biological Nearctic Regional Section.
- Adjunct Professor (2011) Anhui Agricultural University, Hefei, Anhui, China
- Pilarska, D., Hajek, A. E., Keena, M., Linde, A., Kereselidze, M., Georgiev, G., Georgieva, M., Mirchev, P., Takov, D., & Draganova, S. (2016). Susceptibility of larvae of nun moth, Lymantria monacha (Linnaeus, 1758) (Lepidoptera), to the Entomopathogenic fungus Entomophaga maimaiga Humber, Shimazu and Soper (Entomophthorales) under laboratory and field conditions. Acta Zoologica Bulgarica. 68:117-126.
- Hajek, A. E., Hurley, B. P., Kenis, M., Garnas, J. R., Bush, S. J., Wingfield, M. J., van Lenteren, J. C., Cock, M. J., & , (2016). Exotic biological control agents: a solution or contribution to arthropod invasions? Biological Invasions. 18:953-969.
- Hajek, A. E., & Nouhuys, S. V. (2016). Fatal diseases and parasitoids: from competition to facilitation in a shared host. Proceedings of the Royal Society of London Series B. 283: 20160154.
- Wingfield, M. J., Garnas, J. R., Hajek, A. E., Hurley, B. P., de Beer, Z. W., & Taerum, S. J. (2016). Novel and co-evolved associations between insects and microorganisms as drivers of forest pestilence. Biological Invasions. 18:1045–1056.
- Caetano, I. A., Morris, E. E., & Hajek, A. E. (2016). Growth of the Sirex-parasitic nematode Deladenus siricidicola on the white rot fungus Amylostereum. Journal of Invertebrate Pathology. 134:12-14.
- Castrillo, L. A., Hajek, A. E., Pajares, J. A., Thomsen, I. M., Csoka , G., Kenaley, S. C., Kepler, R. M., Zamora, P., & Angeli, S. (2015). Multilocus genotyping of Amylosterum spp. associated with Sirex noctilio and other woodwasps from Europe reveal clonal lineage introduced to the US. Fungal Biology. 119:595-604.
- Fisher, J. J., & Hajek, A. E. (2015). Maternal exposure of a beetle to pathogens protects offspring against fungal disease. PLoS One. 10:e0125197 .
- Goble, T., Hajek, A. E., Jackson, M. A., & Gardescu, S. (2015). Microsclerotia applied in hydromulch: evaluating Metarhizium brunneum F52 for control of Asian longhorned beetles (Coleoptera: Cerambycidae). Journal of Economic Entomology. 108:433-443.
- Hajek, A. E., Tobin, P. C., & Haynes, K. J. (2015). Replacement of a dominant viral pathogen by a fungal pathogen does not alter the synchronous collapse of a forest insect outbreak. Oecologia. 177:785-797.
- Castrillo, L. A., & Hajek, A. E. (2015). Detection of presumptive mycoparasites associated with Entomophaga maimaiga resting spores in forest soils. Journal of Invertebrate Pathology. 124:87-89.
Presentations and Activities
- Safe use of exotic agents for biological control in forests. Annual meeting, North American Forest Insect Work Conference . June 2016. North American Forest Insect Work Conference. Washington DC.
- Challenges facing biological control of invasive arthropods. Annual meeting, USDA Interagency Research Forum on Invasive Species. January 2016. USDA. Annapolis, MD.
- Gypsy moth, its natural enemies and outbreak dynamics. IDEP Symposium, Eastern Branch, ESA. January 2016. Eastern Branch, Entomological Society of America. Philadelphia.
- Temporal density dependence of Entomophaga maimaiga. Society for Invertebrate Pathology. August 2015. . Vancouver, British Columbia, Canada.
- Adding biological control to eradication of Asian longhorned beetles. Entomological Society of America, Eastern Branch. March 2015. Rehoboth Beach, DE.
- Avoiding or joining neighbors: Responses of Sirex females to symbiotic fungi. USDA Interagency Research Forum on Invasive Species. January 2015. Annapolis, MD.
- Eradication and management of invasive arthropods. Drivers, Mechanisms and Impacts of Insect Invasions. November 2014. Centre for Excellence for Invasion Biology, Stellenbosch University. Stellenbosch, South Africa .
- Pathogens, parasites and crashing gypsy moth populations. Entomological Society of America, National meeting. November 2014. Entomological Society of America. Portland, OR.
- Ecology and biological control of invasive forest pests. 5th National Conference on Forest Protection and the International Workshop on Green Forest Pest Control. October 2014. International Workshop on Green Forest Pest Control. Linan, Zhejiang, China .
- Interactions among fungal and viral pathogens and parasitoids. Annual Meeting, Society for Invertebrate Pathology. August 2014. Society for Invertebrate Pathology. Mainz, Germany.