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Range expansion of Lymantria dispar dispar (L.) (Lepidoptera: Erebidae) along its north‐western margin in North America despite low predicted climatic suitability
Author(s) -
Streifel Marissa A.,
Tobin Patrick C.,
Kees Aubree M.,
Aukema Brian H.
Publication year - 2019
Publication title -
journal of biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 158
eISSN - 1365-2699
pISSN - 0305-0270
DOI - 10.1111/jbi.13474
Subject(s) - lymantria dispar , overwintering , erebidae , lepidoptera genitalia , dispar , gypsy moth , range (aeronautics) , subarctic climate , ecology , biology , geography , entamoeba histolytica , materials science , microbiology and biotechnology , composite material
Aim The European gypsy moth, Lymantria dispar dispar (L.), (Lepidoptera: Erebidae) is an invasive defoliator that has been expanding its range in North America following its introduction in 1869. Here, we investigate recent range expansion into a region previously predicted to be climatically unsuitable. We examine whether winter severity is correlated with summer trap captures of male moths at the landscape scale, and quantify overwintering egg survivorship along a northern boundary of the invasion edge. Location Northern Minnesota, USA . Methods Several winter severity metrics were defined using daily temperature data from 17 weather stations across the study area. These metrics were used to explore associations with male gypsy moth monitoring data (2004–2014). Laboratory‐reared egg masses were deployed to field locations each fall for 2 years in a 2 × 2 factorial design (north/south aspect × below/above snow line) to reflect microclimate variation. Rates of successful egg hatch were assessed the following springs. Results Reductions in summer male moth captures are associated with several metrics of winter severity, such as minimum temperatures. Most egg masses suffered >95% mortality each winter. However, hatching success reached up to 80% in egg masses that had overwintered below the snow line (e.g., <30 cm from the ground). Main Conclusions Our findings that cold winter temperatures are associated with reduced summer trap captures of European gypsy moth, likely due to increased overwintering mortality of exposed egg masses, are consistent with previous predictions of thermal range boundaries for this species. However, high survival in egg masses deposited close to the ground are consistent with thermal escape in subnivean environs (i.e., below snow cover), and suggest that further northward range expansion will be likely in areas that receive measurable annual snowfall.