Genetics, Taxonomy, and Ecology of Certain Species of Galerucella (Coleoptera: Chrysomelidae)

Abstract

Two European chrysomelids, Galerucella calmariensis (L.) and G. pusilla (Duftschmidt), show promise as biological control agents against the weed Lythrum salicaria L. (purple loosestrife). G. calmariensis and G. pusilla are sympatric, share the same ecological niche on L. salicaria, and are separated by several morphological characters. These two Galerucella species were genetically compared with another sympatric species, G. grisescens (Joannis), found on Lysimachia vulgaris L. (garden loosestrife) in Europe, and to G. nymphaeae (L.), which occurs on water lilies and other wetland plants such as L. salicaria in Europe and the United States. Two additional species of Galerucella occur in North America: G. stefanssoni Brown, feeding on Rubus chamaemorus L. (cloudberry), and G. quebecensis Brown, feeding on Potentilla palustris (L.) Scop, (marsh-flower). Introduction and establishment of G. calmariensis and G. pusilla to combat L. salicaria would increase to five the number of Galerucella species in North America. The five species are keyed, described, and the adult and male genitalia are figured. An isozyme comparison of 33 loci among three species of Galerucella from Germany verified that G. calmariensis, G. pusilla, and G. grisescens are distinct species. G. calmariensis has a genetic marker represented by LDH-1. The clustering analysis based on genetic identities and some behavioral characters suggests that G. grisescens is more closely related to G. nymphaeae than to G. calmariensis or G. pusilla. The three United States samples of G. nymphaeae collected from two different host plants showed moderate differentiation. Mean heterozygosity ranged from 0.100 to 0.214 (mean = 0.157) across all six measured populations of G. calmariensis, G. pusilla, G. grisescens, and G. nymphaeae.