Potential interactions between invasive woody shrubs and the gypsy moth (Lymantria dispar), an invasive insect herbivore
As the range of the invasive and highly polyphagous gypsy moth (Lymantria dispar) expands, it increasingly overlaps with forest areas that have been subject to invasion by non-native shrubs. We explored the potential for interactions between these co-occurring invasions through a gypsy moth feeding trial using the following three highly invasive, exotic shrubs: honeysuckle (Lonicera maackii), privet (Ligustrum sinense) and burning bush (Euonymus alatus). We compared these with two native shrubs: spicebush (Lindera benzoin) and pawpaw (Asimina triloba). We fed gypsy moth caterpillars foliage exclusively from one of the five shrubs and measured their relative consumptive rate (RCR), relative growth rate (RGR), and development time (DT). The RCR of gypsy moth was strongly influenced by the species of foliage (F = 31.9; P < 0.0001) with little or no consumption of honeysuckle and privet. Caterpillar RGR was influenced by the shrub species (F = 66.2; P < 0.0001), and those caterpillars fed spicebush, honeysuckle or privet lost weight over the course of the assay. Caterpillar DT was also significantly (F = 11.79, P < 0.0001) influenced by the shrub species and those fed honeysuckle, privet and spicebush died prior to molting. Overall, our data suggest that honeysuckle, privet, and spicebush could benefit (indirectly) from the invasion of gypsy moth, while burning bush and pawpaw could be negatively impacted due to direct effects (herbivory). Similarly, invading gypsy moth populations could be sustained on a shrub layer of burning bush and pawpaw in the event of canopy defoliation. Further field and laboratory analysis is needed to clarify herbivore resistance of invasive shrubs, and to investigate the potential interactions among co-occurring insect and plant invasions.
KeywordsForest understory Euonymus alatus Lonicera maackii Lindera benzoin Asimina triloba
This work was supported by University of Kentucky Faculty Research Support Grant. We thank, Jean-Paul Baptiste, Ryan Quire, Melanie Antonik and Tom Coleman for assistance with data collection. Jim Lempke at the University of Kentucky Arboretum provided access to plant material. This study (# 08-09-080) is connected with a project of the Kentucky Agricultural Experiment Station and is published with the approval of the director.
- Campbell RW, Sloan RJ (1977) Forest stand response to defoliation by the gypsy moth. For Sci Monogr 19:1–33Google Scholar
- Davidson CB, Gottschalk KW, Johnson JE (1999) Tree mortality following defoliation by the European gypsy moth (Lymantria dispar L.) in the United States: a review. For Sci 45:74–84Google Scholar
- Hartman KM, McCarthy BC (2007) A dendro-ecological study of forest overstorey productivity following the invasion of the non-indigenous shrub Lonicera maackii. J Appl Veg Sci 10:13–24Google Scholar
- Hintze J (2004) NCSS and PASS. Number Cruncher Statistical Systems. Kaysville, UTGoogle Scholar
- Leibhold AM, Gottshalk KW, Muzika R, Montgomery ME, Young R, O’Day K et al (1995) Suitability of North American tree species to the Gypsy Moth: a summary of field and laboratory tests. USDA Forest Service General Technical Report NE-211, Radnor, PA, USAGoogle Scholar
- McEwan RW, Arthur-Paratley LG, Rieske LK, Arthur MA Inhibition of seed germination by Amur honeysuckle (Lonicera maackii). Am Midl Nat (in review)Google Scholar
- Miller JH (2003) Nonnative invasive plants of southern forests: a field guide for identification and control. Gen. Tech. Rep. SRS-62. U.S. Department of Agriculture, Forest Service, Southern Research Station, Asheville, NC, 93 ppGoogle Scholar
- Naidoo R, Lechowicz MJ (2001) Effects of gypsy moth on radial growth of deciduous trees. For Sci 47:338–348Google Scholar
- Penuelas J, Sardans J, Stefanescu C, Parella T, Filella I (2006) Lonicera implexa leaves bearing naturally laid eggs of the specialist herbivore Euphydryas aurinia have dramatically greater concentrations of iridoid glycosides than other leaves. J Chem Ecol 32:1925–1933. doi: 10.1007/s10886-006-9118-8 PubMedCrossRefGoogle Scholar
- Uesato S, Kanomi S, Iida A, Inouye H, Zenk MH (1986) Mechanism for iridane skeleton formation in the biosynthesis of secologanin and indole alkaloids in Lonicera tartarica, Catharanthus roseus and suspension cultures of Rauwolfia serpentinia. Phytochemistry 25:839–842. doi: 10.1016/0031-9422(86)80012-7 CrossRefGoogle Scholar