Evaluation of Mortality of Galerucella Calmariensis L. (Coleoptera: Chrysomelidae) Preimaginal Life Stages and Pupal Survival at Two Wetlands in Iowa

Abstract

Abstract To quantify mortality of Galerucella calmariensis L. preimaginal life stages in wetlands, which influences levels of biological control of purple loosestrife, Lythrum salicaria L., we sampled G. calmariensis for 19 wk during 2004 in two Iowa wetlands. At each site, we randomly collected 15 to 19 L. salicaria stems that were either surrounded by water or not surrounded by water for a total of 30 stems per site on each sample date. At each site, partial life tables were constructed for egg, first instar, and second–third instars. Stem location (surrounded by water and not surrounded by water) did not affect mortality from egg to second–third instar, thus data were pooled to create a partial life table for each site. At Site 1, insect predators (Coccinellidae) were present on 16% of the sampled dates and at Site 2 insect predators (Coccinellidae and Chrysopidae) were present on 11% of the sampled dates. Mortality from egg to second–third instar was over 99% at both sites. Using the same L. salicaria...