Current Research

With expertise in the ecology and evolution of multi-trophic interactions, I work to provide information about invasive pests, their natural enemies, and the impacted trees. Understanding the interactions among these trophic levels is critical to making sound management decisions to reduce the impact of invasive pests. Facets of my research objectives include investigating: 1) systematics and population genetics of invasive pests, especially hemlock woolly adelgid, balsam woolly adelgid, gypsy moth, and winter moth; 2) systematics and population genetics of predators and parasitoids being evaluated as biological control agents of invasive species, especially of hemlock woolly adelgid and emerald ash borer; and 3) systematics and biogeography of North American tree species and their relatives worldwide.

My goal is to help reconstruct the evolutionary history of multiple trophic levels of a pest system to guide management and mitigate the impact of invasive insect pests on forested ecosystems of the northeastern United States. I am especially concerned with research related to classical biological control to develop practical, cost effective tools used to evaluate the safety and efficacy of predators or parasites introduced as biological control agents.

Why This Research is Important

The exotic invasive pests that are the subject of this research originated in either Asia or Europe. Invasive insects in North America are not often pests in their region of origin due to resistant tree species and natural enemies that co-evolved with the pest over millions of years. The insect becomes a pest following introduction outside its native ranges when these bottom-up and/or top-down regulating factors are no long effective. The hemlock woolly adelgid, Adelges tsugae (Adelgidae), originated in Japan and causes the death and decline of eastern North American hemlock trees in 17 eastern states. The balsam woolly adelgid, Adelges piceae (Adelgidae), originated in Europe and has been killing fir trees throughout North America for over 100 years. The gypsy moth, Lymantria dispar (Lymantriidae), also was also introduced from Europe over 100 years ago. It is controlled to some extent by a pathogenic fungus in areas where it is well established, so management in the U. S. currently focuses on slowing its spread and on preventing invasion by more virulent strains from Asia. The winter moth, Operophtera brumata (Geometridae), is also from Europe and defoliates a broad range of tree species, including oaks and birches in southern New England, and is hybridizing with the native Bruce spanworm, O. bruceata. Finally, the emerald ash borer, Agrilus planipennis (Buprestidae) originated in Asia, was first discovered in the U.S. in Michigan in 2002, and has killed tens of millions of ash trees in at least 15 eastern states. Together, these pest species represent a diverse group of insects with very different feeding strategies, life cycles, host ranges, and natural enemy complexes.

Education

• Yale University, Ph.D. Ecology & Evolutionary Biology 2006
• Yale University, M.S. Ecology & Evolutionary Biology 2003
• University of Wisconsin, Madison, M.S. Entomology 1998
• College of William and Mary, B.S. Biology 1996

Professional Organizations

• Society For The Study Of Evolution, Member (2012 - Current)
• Connecticut Entomological Society, Member (2001 - Current)
• Entomological Society of America, Member (1996 - Current)

Featured Publications & Products

• Havill, Nathan P.; Montgomery, Michael E.; Keena, Melody. 2011. Hemlock woolly adelgid and its hemlock hosts: A global perspective.
• Michael E., Montgomery; Shiyake, S.; Havill, Nathan P. . 2011. A new species of Laricobius (Coleoptera: Derodontidae) from Japan with phylogeny and a key for native and introduced congeners in North America.
• Havill, Nathan P.; Salom, Scott; Davis, Gina; Fischer, Melissa; Mausel, David; Onken, Bradley. 2011. The introduction of Laricobius nigrinus as a biological control agent for the hemlock woolly adelgid: Is there a threat to the native congener, L. rubidus.

Publications

• Mech, Angela M.; Harper, Sherilyn J.; Havill, Nathan P.; von Dohlen, Carol D.; Burke, Gaelen R. 2019. Ecological factors influencing the beneficial endosymbionts of the hemlock woolly adelgid (Hemiptera: Adelgidae).
• Wantuch, Holly A.; Havill, Nathan P.; Hoebeke, E. Richard; Kuhar, Thomas P.; Salom, Scott M. 2019. Predators associated with the pine bark adelgid (Hemiptera: Adelgidae), a native insect in Appalachian forests, United States of America, in its southern range.
• Russo, Nicholas J.; Elphick, Chris S.; Havill, Nathan P.; Tingley, Morgan W. 2019. Spring bird migration as a dispersal mechanism for the hemlock woolly adelgid.
• Picq, Sandrine; Keena, Melody; Havill, Nathan; Stewart, Don; Pouliot, Esther; Boyle, Brian; Levesque, Roger C.; Hamelin, Richard C.; Cusson, Michel. 2018. Assessing the potential of genotyping-by-sequencing-derived single nucleotide polymorphisms to identify the geographic origins of intercepted gypsy moth (Lymantria dispar) specimens: A proof-of-concept study.
• Havill, Nathan P.; Gaimari, Stephen D.; Caccone, Adalgisa. 2018. Cryptic east-west divergence and molecular diagnostics for two species of silver flies (Diptera: Chamaemyiidae: Leucopis ) from North America being evaluated for biological control of hemlock woolly adelgid.
• Darr, Molly; Salom, Scott; Brooks, Rachel K.; Foottit, Robert G.; Miller, Gary L.; Havill, Nathan P. 2018. First report of Pineus strobi (Hartig, 1839) (Hemiptera: Adelgidae) in western North America.
• Weglarz, Kathryn M.; Havill, Nathan P.; Burke, Gaelen R.; von Dohlen, Carol D. 2018. Partnering With a Pest: Genomes of Hemlock Woolly Adelgid Symbionts Reveal Atypical Nutritional Provisioning Patterns in Dual-Obligate Bacteria.
• Darr, Molly ; Brooks, Rachel ; Havill, Nathan ; Hoebeke, E. ; Salom, Scott . 2018. Phenology and Synchrony of Scymnus coniferarum (Coleoptera: Coccinellidae) with Multiple Adelgid Species in the Puget Sound, WA, USA.
• Holman, Garth; Del Tredici, Peter; Havill, Nathan; Lee, Nam Sook; Cronn, Richard; Mathews, Sarah; Raubeson, Linda; Campbell, Christopher S. 2017. A new species and introgression in eastern Asian hemlocks (Pinaceae: Tsuga).
• Havill, N.P.; Elkinton, J.; Andersen, J.C.; Hagen, S.B.; Broadley, Hannah J.; Boettner, G.J.; Caccone, A. 2017. Asymmetric hybridization between non-native winter moth, Operophtera brumata (Lepidoptera: Geometridae), and native Bruce spanworm, Operophtera bruceata, in the Northeastern United States, assessed with novel microsatellites and SNPs.
• von Dohlen, Carol D.; Spaulding, Usha; Patch, Kistie B.; Weglarz, Kathryn M.; Foottit, Robert G.; Havill, Nathan P.; Burke, Gaelen R. 2017. Dynamic Acquisition and Loss of Dual-Obligate Symbionts in the Plant-Sap-Feeding Adelgidae (Hemiptera: Sternorrhyncha: Aphidoidea).
• Andersen, Jeremy C.; Havill, Nathan P.; Caccone, Adalgisa; Elkinton, Joseph S. 2017. Postglacial recolonization shaped the genetic diversity of the winter moth (Operophtera brumata) in Europe.
• Havill, Nathan P. ; Shiyake, Shigehiko; Lamb Galloway, Ashley; Foottit, Robert G.; Yu, Guoyue; Paradis, Annie; Elkinton, Joseph; Montgomery, Michael E.; Sano, Masakazu; Caccone, Adalgisa. 2016. Ancient and modern colonization of North America by hemlock woolly adelgid, Adelges tsugae (Hemiptera: Adelgidae), an invasive insect from East Asia.
• Fischer, Melissa J.; Brewster, Carlyle C.; Havill, Nathan P.; Salom, Scott M.; Kok, Loke T. 2015. Assessment of the potential for hybridisation between Laricobius nigrinus (Coleoptera: Derodontidae) and Laricobius osakensis, predators of the hemlock woolly adelgid (Hemiptera: Adelgidae).
• Arsenault, Arielle L.; Havill, Nathan P. ; Mayfield, Albert E.; Wallin, Kimberly F. 2015. Behavioral Responses of Laricobius spp. and Hybrids (Coleoptera: Derodontidae) to Hemlock Woolly Adelgid and Adelgid Host Tree Odors in an Olfactometer.
• Favret, Colin; Havill, Nathan P. ; Miller, Gary L.; Sano, Masakazu; Victor, Benjamin. 2015. Catalog of the adelgids of the world (Hemiptera, Adelgidae).
• Fischer, Melissa J.; Havill, Nathan P.; Brewster, Carlyle C.; Davis, Gina A.; Salom, Scott M.; Kok, Loke T. 2015. Field assessment of hybridization between Laricobius nigrinus and L. rubidus, predators of Adelgidae.
• Havill, Nathan P.; Vieira, Ligia C.; Salom, Scott M. 2014. Biology and control of hemlock woolly adelgid.
• Fischer, Melissa J.; Havill, Nathan P.; Jubb, Carrie S.; Prosser, Sean W.; Opell, Brent D.; Salom, Scott M.; Kok, Loke T. 2014. Contamination delays the release of Laricobius osakensis for biological control of hemlock woolly adelgid: cryptic diversity in Japanese Laricobius spp.
• Mayfield, Albert E., III.; Reynolds, Barbara C.; Coots, Carla I.; Havill, Nathan P.; Brownie, Cavell; Tait, Andrew R.; Hanula, James L.; Joseph, Shimat V.; Galloway, Ashley B. 2014. Establishment, hybridization and impact of Laricobius predators on insecticide-treated hemlocks: Exploring integrated management of the hemlock woolly adelgid.
• Havill, Nathan P.; Vieira, Ligia C.; Salom, Scott M. 2014. Hemlock woolly adelgid: a threat to eastern forests.
• Jones, C.E.; Havill, Nathan P. ; Hanula, James; Braman, S.K. 2014. Post release recovery of hemlock woolly adelgid predators in the North Georgia mountains..
• Ravn, H.P.; Havill, N.P.; Akbulut, S.; Foottit, R.G.; Serin, M.; Erdem, M.; Mutun, S.; Kenis, M. 2013. Dreyfusia nordmannianae in Northern and Central Europe: potential for biological control and comments on its taxonomy.
• Havill, N.P.; Davis, Gina; Mausel, David; Klein, Joanne; McDonald, Richard; Jones, Cera; Fischer, Melissa; Salom, Scott; Caccone, Adelgisa. 2012. Hybridization between a native and introduced predator of Adelgidae: An unintended result of classical biological control.
• Davis, G.A.; Havill, N.P.; Adelman, Z.N.; Caccone, A.; Kok, L.T.; Salom, S.M. 2011. DNA barcodes and molecular diagnostics to distinguish an introduced and native Laricobius (Coleoptera: Derodontidae) species in eastern North America.
• Havill, Nathan P.; Davis, Gina; Klein, Joanne; Caccone, Adalgisa; Salom, Scott. 2011. Hemlock woolly adelgid biological control: molecular methods to distinguish Laricobius nigrinus, L. rubidus, and their hybrids.
• Sano, Masakazu; Havill, Nathan P.; Ozaki, Kenichi. 2011. Taxonomic identity of a galling adelgid (Hemiptera: Adelgidae) from three spruce species in central Japan.
• Yang, Zi-xiang; Chen, Xiao-ming; Havill, Nathan P.; Feng, Ying; Chen, Hang. 2010. Phylogeny of Rhus gall aphids (Hemiptera:Pemphigidae) based on combined molecular analysis of nuclear EF1α and mitochondrial COII genes.
• Havill, Nathan P.; Klein, Joanne; Keena, Melody A.; Caccone, Adalgisa. 2009. Characterization of microsatellite loci for Laricobius nigrinus and L rubidus, predators of adelgids in North America.
• Foottit, R.G.; Maw, H.E.L.; Havill, N.P.; Ahern, R.G.; Montgomery, M.E. 2009. DNA barcodes to identify species and explore diversity in the Adelgidae (Insecta: Hemiptera: Aphidoidea).
• Havill, Nathan P.; Montgomery, Michael; Shiyake, Shigehiko; Lamb, Ashley; Keena, Melody A.; Caccone, Adalgisa. 2009. Hemlock woolly adelgid population genetics.
• Havill, Nathan P.; Montgomery, Michael E. 2008. The role of arboreta in studying the evolution of host resistance to the hemlock woolly adelgid.
• Butin, Elizabeth; Elkinton, Joseph; Havill, Nathan; Montgomery, Michael. 2003. Comparative impact of Scymnus ningshanensis and Pseudoscymnus tsugae (Coleoptera: Coccinellidae) on the hemlock woolly adelgid.
• Montgomery, Michael; Havill, Nathan; Cheah, Carole; McClure, Mark; Zilahi-Balogh, Gabriella; Lamb, Ashley; Salom, Scott. 2003. Hemlock woolly adelgid biological control research.
• Montgomery, Michael; Wang, Hongbin; Yao, Defu; Lu, Wenhau; Havill, Nathan; Li, Guangwu. 2002. Biology of Scymnus ningshanensis (Coleoptera: Coccinellidae): A predator of Adelges tsugae (Homoptera: Adelgidae).
• Butin, Elizabeth; Montgomery, Montgomery; Havill, Nathan; Elkinton, Joseph. 2002. Pre-release host range assessment for classical biological controls: experience with predators for the hemlock woolly adelgid.

Research Highlights

Highlight	Title	Year
NRS-2015-166	First Release of a New Biological Control of Hemlock Woolly Adelgid Forest Service scientists and their research partners tested and released two species of silver flies from the western United States for biologi ...	2015
NRS-2016-144	Non-native Insect Hybridization Provides Opportunity for Research A recent outbreak in New England of the non-native winter moth from Europe provides an unprecedented opportunity to examine the effects of hybri ...	2016
NRS-2017-56	Silver flies show promise as potential biological controls of hemlock woolly adelgid Forest Service science is identifying potential biological control of hemlock wooly adelgid, an invasive insect that is devastating hemlock tree ...	2017