Phenological Features of the Spongy Moth, Lymantria dispar (L.) (Lepidoptera: Erebidae), in the Northernmost Portions of Its Eurasian Range

Abstract

The spongy moth, Lymatria dispar, is a classic example of an invasive pest accidentally introduced from Europe to North America, where it has become one of the most serious forest defoliators, as in its native range. The present study was aimed at (i) identifying the current northern limit of L. dispar’s Eurasian range and exploring its northward expansion in Canada using pheromone trap data, and (ii) comparing northern Eurasian populations with those from central and southern regions with respect to male flight phenology, the sums of effective temperatures (SETs) above the 7 °C threshold necessary for development to the adult stage, and heat availability. We show that the range of L. dispar in Eurasia now reaches the 61st parallel, and comparisons with historical data identify the average speed of spread as 50 km/year. We also document the northern progression of L. dispar in southern Canada, where the actual northern boundary of its range remains to be identified. We show that the median date of male flight does not vary greatly between northern and southern regions of the spongy moth range in Eurasia despite climate differences. Synchronization of flight at different latitudes of the range is associated with an acceleration of larval development in northern Eurasian populations. Similar changes in developmental rate along a latitudinal gradient have not been documented for North American populations. Thus, we argue that this feature of spongy moths from northern Eurasia poses a significant invasive threat to North America in terms of enhanced risks for rapid northward range expansion.

Feasting on the ordinary or starving for the exceptional in a warming climate: Phenological synchrony between spongy moth (Lymantria dispar) and budburst of six European tree species

“…However, due to asymmetric temperature responses, other tree species that currently leaf out before the hatching of L. dispar may soon enter the optimal time window of the moth as climate continues to warm. Similarly, as L. dispar migrates farther to northern latitudes (Ponomarev et al., 2023), its phenology could match that of tree species that were too late in southern latitudes, as it has been recently found for the eastern spruce budworm with black spruce in North America (Bellemin‐Noël et al., 2021).…”

Temperature- and Diet-Induced Plasticity of Growth and Digestive Enzymes Activity in Spongy Moth Larvae

“…Global warming affects synchrony/asynchrony between SML hatching and host plant budding, leading to different scenarios of interaction between temperature and leaf quality that influence larval development, susceptibility to natural enemies, population dynamics, and host plant defoliation [100][101][102][103]. As confirmed by data on SM [99,104,105] and the closely related nun moth [106], another consequence of global warming is the spread of the pest to northern geographic regions where new dominant hosts with different leaf chemistry are encountered. Under these circumstances, the energy balance of food utilization determines survival, host acceptance for feeding, successful development, body size, female fecundity, flight potential of males, and thus invasion dynamics [107][108][109].…”