Peering into predictors at the spongy moth invasion front
Metz, R., Tobin, P.C. Effects of temperature and host plant fragmentation on Lymantria dispar population growth along its expanding population front. Biol Invasions 24, 2679–2691 (2022). https://doi.org/10.1007/s10530-022-02804-8
Summary written by Justin Dalaba, edited by Audrey Bowe
Shifting temperature regimes can influence the suitability and spread of invasive insects like Lymantria dispar (spongy moth). However, the role of secondary host plants in supporting L. dispar expansion across the U.S. has received little research attention, until now.
With projected temperature shifts in a changing climate, the distributions of native and invasive insects are expected to shift as well. In this study, Metz and Tobin highlight how geographical differences in temperature and host plant fragmentation may affect Lymantria dispar (spongy moth, formerly gypsy moth) growth rates along the expanding invasion front. Growth rates for L. dispar were derived from monitoring data collected by Slow-the-Spread, a program which has extensively monitored the population front from Minnesota to North Carolina using ~100,000 georeferenced traps. Temperature data were obtained through the PRISM Climate Group, using daily minimum January and mean daily maximum July temps. U.S. Forest Service inventory data from private and federal lands helped quantify the mean amount of area occupied by tree stems within each study region. They used the spatial modeling software, FRAGSTATS 3.3., to estimate connectivity across the landscape (mean patch cohesion) for primary and secondary host plants. Secondary host plants differ from primary hosts in that they can generally only be consumed by later instars. Overall, they found mean growth rates were highest in the Northern region and lowest in the Midwestern region. Temperature was the main predictor for lower growth rates in the Midwestern region, where colder overwintering conditions are likely. Secondary host species cohesion and its interaction with primary host species cohesion significantly predicted growth rates in the Northern region, emphasizing the importance of reduced fragmentation in the invasion of L. dispar. In the Southern region, they observed higher L. dispar growth rates as both primary and secondary host plant cohesion increased.
- From 16 years of spatially-referenced data, this study found the highest L. dispar growth rates when minimum January temperatures were > -10 °C and July temps between 27-30 °C
- Warming winter temperatures in the Northern region will likely further increase the speed and growth of L. dispar invasion, which is particularly concerning for regions previously considered climatically unsuitable
- In the Northern and Southern regions, they detected higher growth rates when there was less fragmentation (higher cohesion) of both primary and secondary host plants
- In the Midwest region where there is a lower density of host plants, L. dispar growth rates would decrease with low January temperatures and high temperatures in July
- Host plant availability is key to incorporate in risk models when predicting establishment of invasive species
- Rather than focusing solely on host plant density, including host plant cohesion, a measure of connectivity, as a factor in risk models could improve predictive capability of risk assessment models for herbivorous invasive insects
- Better understanding predictors of population spread can help managers prepare for the growth of invasive insect populations under shifting climatic suitability
Read more of our research summaries:
Invasive species vocalizations may be a significant avenue for competition among species. This thought-provoking article gives a glimpse into the potential effects of invasive species disrupting a soundscape.
Shifting temperature regimes can influence the suitability and spread of invasive insects, including spongy moth. How can secondary host plant connectivity support its expansion across the U.S.?
Can invasive worms serve as food for native species? How do they alter leaf litter microhabitat? New research offers insight into the potential effects and trophic interactions of jumping worms (Amynthas spp.) and native reptiles and amphibians.
Public gardens are in a unique position to form a sentinel network to aid in detecting potential invasive species. This study informs how public gardens can collectively contribute data for potential new invaders.
How accessible is invasive species literature? A detailed analysis of the leading journal, Biological Invasions, points to a decline in readability for key stakeholders over two decades.
How do we make use of new and existing technologies for early detection of aquatic invasive species? This study demonstrates how DNA barcoding can aid in identification of non-indigenous mollusks from New York’s waterways.
With Spring setting in, plants are not the only thing emerging from the forest floor. Many frog and salamander species are on the move, but how might invasive plant management impact these ecologically important taxa?
Using the InvaCost database, this study reports the most up-to-date and exhaustive overview of global spending for invasive species management, revealing important insights into spending trends and the cost of inaction.
In recognition of black history month, we are sharing an important paper that reflects on how we can construct a more equal, inclusive, and socially just conservation field.
A team of researchers and practitioners tackles the disconnect between research and application in the field of remote sensing for invasive species, summarizing 40+ years of literature and experience.
To round out the year, we’re sharing an approach that TIEs together actionable research with invasive species management and policy decisions, called Translational Invasion Ecology (TIE).