Shawn Steffan
he/him
Associate Professor, USDA-ARS & UW-Madison
Interests: Cranberry IPM, community ecology, biological control
(608) 890-1281
545 Russell Labs
1630 Linden Drive
Madison, WI 53706
Education
- Ph.D. Entomology – Washington State University, 2009
- MS Entomology – University of Wisconsin-Madison,1997
- BA Environmental Science – University of California-Berkeley,1993
Affiliations
- Research Entomologist, USDA-ARS
Research Interests
As a Research Entomologist with the USDA-ARS, as well as a UW faculty member in the Dept. of Entomology, my work centers on basic and applied aspects of cranberry entomology and ecology. Studies are designed to refine IPM strategies while providing a mechanistic understanding of key ecosystem functions.
Through national and international collaborations with both public and private institutions/companies, my team is focusing on innovative crop protection strategies while doing basic science.
Near-term studies focus on biological, cultural, and chemical controls of the major insect pests of cranberry, with particular emphases on 1) pheromone-based mating disruption programs for the top cranberry pests in Wisconsin; 2) phenology of Sparganothis fruitworm, black-headed fireworm, and cranberry fruitworm; 3) refinement of flood-timing as an IPM strategy; 4) flea beetle biology and control.
Longer-term studies involve the analysis of community composition and trophic structure (the foodweb) of the cranberry system. This work will allow us to measure the “trophic niches” of an arthropod community (i.e., who tends to eat whom), which may differ between cultivated and wild/feral cranberry populations, as well as between decades (an effect of climate change). Differing trophic signatures may serve as indicators of desirable horticultural traits in a cranberry population, which ultimately could facilitate the development of improved cranberry varieties.
Publications
Online Profiles
Recent Publications
-
Environmental microbiology reports. pmid:41788021, pmc:PMC12963932, doi:10.1111/1758-2229.70310
Pollinators are known dispersal agents of microbial communities between flowering plants, although the role of insect-mediated microbial assembly in flowering agricultural crops is not well understood. In cranberry (Vaccinium macrocarpon Ait.) agroecosystems, the blossom period is a vulnerable time for infection from pathogens within the cranberry fruit rot fungal disease complex, and understanding the components and assembly dynamics in cranberry flower fungal communities may provide important…
-
Insects. pmid:41752602, pmc:PMC12942308, doi:10.3390/insects17020199
Pollen acts as both a gametophyte for plant reproduction and a vital nutrient source for bees. Adult honey bees (Apis mellifera) mix pollen with nectar, enzymes, and microbes to create ‘bee bread’, diverting pollen from plant reproduction and re-appropriating it as larval food. However, the point at which corbicular pollen becomes nonviable is largely unknown. This question is important not only because it explicitly addresses pollen viability while bees pollinate, but also because it informs…
-
Journal of visualized experiments : JoVE. pmid:41587203, doi:10.3791/69678
Entomopathogenic nematodes (EPNs) produced through in vitro or in vivo methods are highly effective biocontrol agents for insect pest management. In vivo mass-propagation systems result in high-quality nematodes but are often more labor-intensive and/or less cost-effective than commercial in vitro methods. Grower-oriented nematode propagation systems described to date are generally unreliable because they rely on external sources (industry or academic laboratories) to calibrate the inoculum. We…
-
Ecology. pmid:40078012, pmc:PMC11904393, doi:10.1002/ecy.70063
No abstract
-
Trends in ecology & evolution. pmid:37940503, doi:10.1016/j.tree.2023.09.001
While bee-angiosperm mutualisms are widely recognized as foundational partnerships that have shaped the diversity and structure of terrestrial ecosystems, these ancient mutualisms have been underpinned by ‘silent third partners’: microbes. Here, we propose reframing the canonical bee-angiosperm partnership as a three-way mutualism between bees, microbes, and angiosperms. This new conceptualization casts microbes as active symbionts, processing and protecting pollen-nectar provisions,…
-
Journal of insect science (Online). pmid:37721498, pmc:PMC10506446, doi:10.1093/jisesa/iead025
Entomopathogenic nematodes in the genera Steinernema and Heterorhabditis, produced through in vitro or in vivo methods, are effective insect biological control agents. In vivo production yields good-quality nematodes, but the costs associated with obtaining insects and labor make this production system have a low economy of scale. Conceivably, if growers can produce their own nematodes, then the cost could be reduced. Grower-based production systems described to-date are not sustainable because…
-
mSystems. pmid:35543104, pmc:PMC9241642, doi:10.1128/msystems.00312-22
Microbial symbiosis drives physiological processes of higher-order systems, including the acquisition and consumption of nutrients that support symbiotic partner reproduction. Metabolic analytics provide new avenues to examine how chemical ecology, or the conversion of existing biomass to new forms, changes over a symbiotic life cycle. We applied these approaches to the nematode Steinernema carpocapsae, its mutualist bacterium, Xenorhabdus nematophila, and the insects they infect. The…
-
Ecology and evolution. pmid:35414891, pmc:PMC8986510, doi:10.1002/ece3.8788
Developing bees derive significant benefits from the microbes present within their guts and fermenting pollen provisions. External microbial symbionts (exosymbionts) associated with larval diets may be particularly important for solitary bees that suffer reduced fitness when denied microbe-colonized pollen.To investigate whether this phenomenon is generalizable across foraging strategy, we examined the effects of exosymbiont presence/absence across two solitary bee species, a pollen specialist…
-
Journal of economic entomology. pmid:34180532, doi:10.1093/jee/toab068
Cranberry fruitworm (Acrobasis vaccinii Riley (Lepidoptera: Pyralidae)) and blackheaded fireworm (Rhopobota naevana Hubner (Lepidoptera: Tortricidae)) threaten cranberry production annually by causing significant fruit damage. Up to four pesticide applications are made each year to control these insects, which are costly to producers and elevate pesticide residues in fruit. Pheromone-based mating disruption technology can provide control of these pests in cranberry production, with the potential…
-
Current opinion in insect science. pmid:32992041, doi:10.1016/j.cois.2020.09.007
Growing evidence reveals strong overlap between microbiomes of flowers and bees, suggesting that flowers are hubs of microbial transmission. Whether floral transmission is the main driver of bee microbiome assembly, and whether functional importance of florally sourced microbes shapes bee foraging decisions are intriguing questions that remain unanswered. We suggest that interaction network properties, such as nestedness, connectedness, and modularity, as well as specialization patterns can…
-
Insects. pmid:32316296, pmc:PMC7240610, doi:10.3390/insects11040250
The pollen stores of bumble bees host diverse microbiota that influence overall colony fitness. Yet, the taxonomic identity of these symbiotic microbes is relatively unknown. In this descriptive study, we characterized the microbial community of pollen provisions within captive-bred bumble bee hives obtained from two commercial suppliers located in North America. Findings from 16S rRNA and ITS gene-based analyses revealed that pollen provisions from the captive-bred hives shared several…
-
Journal of economic entomology. pmid:31943098, doi:10.1093/jee/toz365
The spotted-wing drosophila, Drosophila suzukii Matsumura, is an exotic species in North America and represents a major threat to fruit production. Efforts to manage D. suzukii have focused primarily on insecticides, but such controls may, at times, be unreliable, given that D. suzukii larvae are often ensconced within fruit. The fruit interior, however, may represent suitable foraging substrates for carnivorous/entomopathogenic nematodes. In preliminary trials, a rare nematode species, Oscheius…
-
The American naturalist. pmid:31553217, doi:10.1086/704281
As pollen and nectar foragers, bees have long been considered strictly herbivorous. Their pollen provisions, however, are host to abundant microbial communities, which feed on the pollen before and/or while it is consumed by bee larvae. In the process, microbes convert pollen into a complex of plant and microbial components. Since microbes are analogous to metazoan consumers within trophic hierarchies, the pollen-eating microbes are, functionally, herbivores. When bee larvae consume a…
-
Proceedings. Biological sciences. pmid:31185869, pmc:PMC6571465, doi:10.1098/rspb.2018.2894
Teeming within pollen provisions are diverse communities of symbiotic microbes, which provide a variety of benefits to bees. Microbes themselves may represent a major dietary resource for developing bee larvae. Despite their apparent importance in sustaining bee health, evidence linking pollen-borne microbes to larval health is currently lacking. We examined the effects of microbe-deficient diets on the fitness of larval mason bees. In a series of diet manipulations, microbe-rich maternally…
-
Journal of nematology. pmid:30335908, pmc:PMC6909328, doi:10.21307/jofnem-2018-004
In a search for an entomopathogenic nematode to control cranberry insect pests, three Oscheius populations (Rhabditidae) were recovered through the Galleria-bait method from one sample taken in a wild cranberry marsh in Jackson County, Wisconsin, USA. Morphological studies with light microscopy and scanning electron microscopy, as well as molecular analyses of the near-full-length small subunit rDNA gene, D2/D3 expansion segments of the large subunit rDNA gene, internal transcribed spacer, and…
Selected Publications
- Takizawa, Y., Choi, H., Shibuya, M., Park, N., Dharampal, P. S., Steffan, S. A., & Chikaraishi, Y. (2025). Fractionation of nitrogen isotopes in the enzymatic deamination of alanine: an insight into the quantitative evaluation of anaerobic metabolism in ecosystems. Progress in Earth and Planetary Science, 12(1), 90. https://doi.org/10.1186/s40645-025-00754-y
- Fan, R., Takizawa, Y., Dharampal, P. S., Steffan, S. A., & Chikaraishi, Y. (2025). Carnivorous plants: unveiling trophic identity and advanced nitrogen acquisition strategies. Progress in Earth and Planetary Science, 12(1), 40. https://doi.org/10.1186/s40645-025-00714-6
- Barceló, G., Perrig, P. L., Dharampal, P., Donadio, E., Steffan, S. A., & Pauli, J. N. (2022). More than just meat: carcass decomposition shapes trophic identities in a terrestrial vertebrate. Functional ecology, 36(6), 1473-1482. https://doi.org/10.1111/1365-2435.14041
- Keller, A., McFrederick, Q. S., Dharampal, P., Steffan, S., Danforth, B. N., & Leonhardt, S. D. (2021). (More than) Hitchhikers through the network: the shared microbiome of bees and flowers. Current opinion in insect science, 44, 8-15. https://doi.org/10.1016/j.cois.2020.09.007
- Takizawa, Y., Takano, Y., Choi, B., Dharampal, P. S., Steffan, S. A., Ogawa, N. O., … & Chikaraishi, Y. (2020). A new insight into isotopic fractionation associated with decarboxylation in organisms: implications for amino acid isotope approaches in biogeoscience. Progress in Earth and Planetary Science, 7(1), 50. https://doi.org/10.1186/s40645-020-00364-w
- Dharampal, P. S., Hetherington, M. C., & Steffan, S. A. (2020). Microbes make the meal: oligolectic bees require microbes within their host pollen to thrive. Ecological Entomology, 45(6), 1418-1427. https://doi.org/10.1111/een.12926
- Foye, S., & Steffan, S. (2019). Two native Wisconsin nematodes represent virulent biocontrol agents in cranberries. Biological Control, 138, 104042. https://doi.org/10.1016/j.biocontrol.2019.104042
- Guzman, A., Gaines-Day, H. R., Lois, A. N., Steffan, S. A., Brunet, J., Zalapa, J., & Guédot, C. (2019). Surrounding landscape and spatial arrangement of honey bee hives affect pollen foraging and yield in cranberry. Agriculture, Ecosystems & Environment, 286, 106624. https://doi.org/10.1016/j.agee.2019.106624
- Pauli, J. N., Manlick, P. J., Dharampal, P. S., Takizawa, Y., Chikaraishi, Y., Niccolai, L. J., … & Steffan, S. A. (2019). Quantifying niche partitioning and multichannel feeding among tree squirrels. Food Webs, 21, e00124. https://doi.org/10.1016/j.fooweb.2019.e00124
Service
Professional Societies
- Member, Ecological Society of America
- Member, Entomological Society of America