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Organized Oral Session

Session: : Advances in Ecological Research Using Remotely-Sensed Earth Observations

OOS 59-5 - Understanding the genetic underpinnings of plant-insect herbivore interactions: the role of remote sensing

Thursday, August 10, 2023

2:30 PM – 2:45 PM PDT

Location: 256

Presenting Author(s)

PD

Phuong Dao

Postdoctoral Research Associate
Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, United States

Co-author(s)

MZ

Mark Zierden

Department of Entomology, University of Wisconsin-Madison
WH

W Beckett Hills

University of Wisconsin
JR

Jennifer Riehl

Department of Entomology, University of Wisconsin-Madison
MF

Michael Friedman

Department of Entomology, University of Wisconsin-Madison
CO

Celso Olivera

Department of Forest and Wildlife Ecology, University of Wisconsin-Madison
TZ

Ting Zheng

University of Wisconsin-Madison
AT

Amy M. Trowbridge

Assistant Professor
University of Wisconsin - Madison
Madison, Wisconsin, United States
RL

Richard L. Lindroth

University of Wisconsin, Madison
Madison, WI, United States
PT

Phil PA Townsend, Ph.D.

Professor
University of Wisconsin - Madison
Madison, Wisconsin, United States

Intraspecific genetic variation in trembling aspen (Populus tremuloides) largely determines the composition of defensive traits among individuals. Different genotypes also exhibit different chemical responses to insect herbivory. However, the role of genetics in differing induced phytochemical responses to herbivores is poorly understood. To understand the genetics-chemical response relationship among aspen genotypes, we investigate the impact of spongy moth (Lymantria dispar) on variation in foliar defensive (phenolic glycosides–PG and condensed tannins–CT) and other functional traits (nitrogen, non-structural carbohydrates–NSC, leaf mass per area–LMA, leaf area density–LAD) on aspen trees from 519 genotypes located in a common garden. Imaging spectroscopy overcomes the uncertainties and limitations of ground-based trait measurements by providing spatially continuous observations across space (i.e., maps) in which consistent and complete data are acquired for all trees. We integrate imaging spectroscopy, LiDAR, and biological modeling with field and lab measurements to characterize the chemical response. The results show that imaging spectroscopy and leaf-level reflectance provide the capacity to quantify defensive and physiological traits over the course of tree phenology and insect herbivory. The substantial increase in CT during defoliation and in PG during leaf reflush indicates a strong chemical response in aspen. The results also indicate there is a trade-off between PG and CT defense mechanisms–trees with high PG tend to have low CT and vice versa. The degree, onset, and duration of the chemical variation were distinct among genotypes, regardless of their pre-defoliation defensive chemical concentrations. As well, the diverse genetic variation in foliar chemistry corresponded to substantial spectral diversity. We observed a decrease in foliar nitrogen that accompanied the increase in defensive traits during and following defoliation, indicating a trade-off in resource allocation in response to herbivory. The results provide insights into genetic variation in plant chemical response for predicting the performance and spread of insects in host species.