Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center
via Google Scholar
Ph.D. Entomology, University of Wisconsin-Madison, 2014
B.S. Agroecology, The Pennsylvania State University, 2008
2021-current, Research Biologist, USDA-ARS, U.S. Pacific Basin Agricultural Research Center, Hilo, Hawaii
2014-2021, Postdoctoral Scholar, Department of Entomology, The Pennsylvania State University
My principal research interests are rooted in how insect herbivores exploit food resources, the obstacles associated with their diets. Many diets can contain deleterious phytochemicals, or have substantial nutritional challenges. One aspect to how insects may exploit dietary resources is by leveraging microbiota harbored in their intestines. My ongoing research explores different aspects of insect-diet-microbiome interactions, with the aim of identifying mechanisms in which microbiota can improve herbivore fitness and how benign microbes in one circumstance can pathogens on deleterious diets. My research group is currently addressing these questions with the tephritid fruit flies.
Microbiome mediation of plant defenses against herbivores:
Insects encounter different types of plant defenses, many of which present significant barriers to herbivore success. One aspect that remains understudied in insect herbivore systems is the presence of antagonistic microbes naturally present in guts, and how they may become opportunistic pathogens. Using the polyphagous fall armyworm, we established axenic rearing techniques to evaluate how plant resistance facilitates the emergence of pathogens. Plant defenses created avenues for invasion by bacterial pathogens. The combined stressors of contending with plant defenses and mounting an immune response to a weak pathogen overwhelms the insect, increasing mortality. However, the strength of the interaction largely depends on the bacteria present in the system, with some bacteria having stronger effects. We explored these interactions using maize and have expanded to tomato and soybean.
Not all microbial interactions are negative, and some might facilitate the digestion of challenging diets. I have explored these types of interactions using artificial diets, using fall armyworm and the invasive gypsy moth as models. Some bacteria can improve the performance of the larvae in the face of challenging diets, with different isolates or complements of bacteria having unique effects on the herbivores.
Characterization of gut microbial communities:
To better understand insect-microbial-plant interactions, characterization of the players involved is essential. Using a combination culture-based microbial curation and next-generation sequencing, we build baseline information essential for guiding future studies and manipulation of communities. Along with collaborators, we have evaluated microbial communities associated with various lepidopteran and coleopteran species.
Our efforts have revealed important trends in how these simple gut microbial communities change in response to the host’s environment. Using different lepidopteran species, I have demonstrated that diet plays a key role in the structure and maintenance of communities. Specifically, when fall armyworm, corn earworm, and gypsy moth encounter different diets, their communities change in response. When we compared communities through the Asian long horned beetle’s lifecycle revealed distinct communities between the adults and larvae, reflecting a different lifestyle and food sources. Our current efforts are to understand the underlying mechanisms driving this variation, and how food chemistry and new microbial invasions alter these dynamics.
Determination of plant resistance against tree pests:
Plants have dynamic responses against attacking insects, and defense against the attacking agent can be life or death circumstance. Through a combination of study systems, I have helped characterize defense components and strategies employed by trees against attacking beetles. Ongoing research involves the characterization of different phytochemicals and how they differ between plant species and genotypes.
Working with conifer and bark beetles, myself and a team of researchers determined how multiple chemical groups are expressed and interrelated to each other and tree nutritional makeup. We also evaluated how radial resin duct characteristics are integrated into the chemical defense responses.
I have also evaluated how tree defenses vary and produce different impacts on various life stages of the invasive Asian longhorned beetle. Asian longhorned beetle adults are incapable of consuming some tree species and fail to generate offspring. However, the plants that the adults cannot consume, the larvae can exploit. These patterns were related to the location of deleterious toxins were in the plant, such that the adults encountered high concentrations, but larvae consumed very little.
Service, Leadership and Participation in Professional Activities:
- Entomological Society of America (current)
- Penn State Department of Entomology Social Committee (2020)
- Penn State College of Agricultural Sciences Graduate Student Competitive Grants Program reviewer (2016)
- Judge for the Penn State Environmental Chemistry and Microbiology Student Symposium (2015-2017)
- Judge for Gamma Sigma Delta Penn State College of Agricultural Sciences Research Exposition (2015-2018)
Honors, Awards, Achievements and Recognition:
- USDA-NIFA Postdoctoral Fellow (2018-2020)
- Recipient of the INRA Early Career Award – International Phytobiomes Conference (2018)
- Recipient of the University of Wisconsin-Madison Department of Entomology Kinney Merit Award (2014)
- Recipient of the NSF Graduate Research Fellowship Honorable Mention (2009)