Spongy Moth Trapping 2023

 

Thank you to all of our collaborators and volunteers who have agreed to set-up and monitor a trap!

You can find the instructions for trap set up and sample collection: here

Please find below a video illustrating the trap take-down, as well as moth collection and mailing procedures.

And here is a video of Jessica demonstrating how to set up the trap!

Contact

Please reach out to Jessica or Patrick with any questions about the traps, installation, or moth collection.

  • Jessica Underwood: j.underwood@mail.utoronto.ca

  • Patrick James: patrick.james@utoronto.ca

Trap location network

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Project Context and Objectives

Outbreaks of forest insect pests, such as the spongy moth (SM; Lymantria dispar dispar) are a significant disturbance to forest ecosystems (Campbell and Sloan 1977). Effective management of large-scale and spatially synchronous outbreaks requires a clear understanding of the spatial processes underlying outbreak initiation, spread, and outcomes. However, spatial and temporal population dynamics in outbreaking species are not well understood. In particular, we know relatively little about the role of dispersal in driving synchronous outbreaks and outbreak spread.

Population and landscape genetics can be used to improve our understanding of how demography, dispersal, and landscape heterogeneity influence outbreak dynamics. Before we can reliably evaluate the relative importance of dispersal and environmental conditions on outbreaks, we require a general understanding of the general population genetic consequences of cyclic irruptive population dynamics (James et al. 2015, Larroque et al. 2019). The goal of this research project is to characterize changes in population genetic variation during the declining phase of a spongy moth outbreak and to further our understanding of how outbreaks affect population genetic inference.

Spongy moth is a naturalized invasive forest insect pest that feeds on a wide range of broad-leaved species in North America. Outbreaks of SM affect public and private lands and have negative ecological, economic, and social consequences. SM exhibit irruptive population outbreaks across large spatial scales. The most recent outbreak is thought to have peaked in 2021 in southern Ontario. At the time, the outbreak affected more than 1.8 million hectares of forest. Since then, the outbreak has declined with only 50,000 ha affected in Ontario in 2022. These dramatic changes in population density and outbreak spatial extent represent excellent opportunities to examine the spatial population genetic consequences of outbreak collapse.

In this project, we will quantify changes in population genetic diversity and spatial structure during the declining phase of the SM outbreak within Ontario as well as in neighbouring jurisdictions (e.g., Quebec, New York). In addition to quantifying empirical spatial genetic variation, we will compare this observed genetic variation to what ones expect from theory and simulation modelling (Mayrand et al. 2019). In this study, we specifically address the following two questions:

  1. What is the spatial genetic structure of SM populations across southern Ontario and Quebec and how does it differ between peak (2021) and declining (2023) outbreak phases?

  2. How well do changes in genetic diversity and structure between peak and declining phase conform with expectations from the literature and simulation models?

Methods

Previously, we collected samples of spongy moth at the outbreak peak in 2021 at over 25 sites. The goal of this project is to follow up on those samples that study in 2021 and collects spongy moth individuals at the same sites to compare and characterize changes in population genetic connectivity between these two points in time. This work will contribute to our theoretical understanding of the population genetic consequences of population outbreaks, as well as further improve our understanding of the spatial extent of population connectivity at different demographic phases of the spongy mouth outbreak.

Male spongy moth specimens will be collected using pheromone baited traps installed across a network of sites with the assistance of numerous collaborators. Our objective is to collect between 20 and 30 moths per location. In 2021, as population densities were so high, it was easy to collect both male and female moths by hand. As densities are now lower in 2023, we will require the use of pheromone traps for effective specimen collection. We plan to repeat this collection in 2025 to capture the spatial genetic signature of endemic SM populations.

Pheromone traps will be installed before the flight period in July. Flight period timing estimates are provided using the phenological modelling tool BIOSim (Régnière and Saint-Amant 2008). Traps will remain active until approximately one week after the predicted phenological window for moth emergence. We are confident that most captured moths will be local in origin given the relatively short dispersal capacity of the SM compared to other outbreaking lepidoptera (e.g., spruce budworm).

Collected moths will be transported to the University of Toronto and stored in a - 80 degrees Celsius freezer until processing. Processing will involve dissection to remove wings and abdomens, followed by DNA extraction using standard protocols for Qiagen DNEasy Blood and Tissue kits (Larroque et al. 2019, Picq et al. 2023). Resulting high quality extracted genomic DNA will be used for double digest RAD sequencing using bioinformatic platforms at the centre for applied genomics and evolution (CAGEF) at the University of Toronto. Sequences will be assembled relative to an existing reference genome (Sparks et al. 2021) and used for SNP identification.

At the end of our sequencing processing, we anticipate having sequence information for several hundred spongy moth individuals across ~25 sites in southern Ontario for the years 2021 and 2023. We will then use these data to characterize changes in genetic variation, population genetic structure, and connectivity across the outbreak range through time.

References

Campbell, R. W., and R. J. Sloan. 1977. Forest stand responses to defoliation by the gypsy moth. Forest Science 23:a0001-z0001.

James, P. M. A., B. Cooke, B. M. T. Brunet, L. M. Lumley, F. A. H. Sperling, M.-J. Fortin, V. S. Quinn, and B. R. Sturtevant. 2015. Life-stage differences in spatial genetic structure in an irruptive forest insect: Implications for dispersal and spatial synchrony. Molecular Ecology 24:296-309.

Larroque, J., S. Legault, R. Johns, L. Lumley, M. Cusson, S. Renaut, R. C. Levesque, and P. M. A. James. 2019. Temporal variation in spatial genetic structure during population outbreaks: Distinguishing among different potential drivers of spatial synchrony. Evolutionary Applications 12:1931-1945.

Mayrand, P., É. Filotas, J. Wittische, and P. M. James. 2019. The role of dispersal, selection, and timing of sampling on the false discovery rate of loci under selection during geographic range expansion. Genome 62:715-727.

Picq, S., Y. Wu, V. V. Martemyanov, E. Pouliot, S. E. Pfister, R. Hamelin, and M. Cusson. 2023. Range‐wide population genomics of the spongy moth, Lymantria dispar (Erebidae): Implications for biosurveillance, subspecies classification and phylogeography of a destructive moth. Evolutionary Applications. 16:638–656.

Régnière, J., and R. Saint-Amant. 2008. BioSIM 9 - User’s Manual, Information Report LAU-X-134. Page 76, Quebec City.

Sparks, M. E., F. O. Hebert, J. S. Johnston, R. C. Hamelin, M. Cusson, R. C. Levesque, and D. E. J. G. Gundersen-Rindal. 2021. Sequencing, assembly and annotation of the whole-insect genome of Lymantria dispar dispar, the European gypsy moth.  11:jkab150.