Monday, December 10, 2007 - 10:41 AM

Overwintering strategies of two entomopathogenic nematodes, Steinernema scarabaei and Heterorhabditis bacteriophora, relative to changing soil temperature and host vertical distribution

Daniel E. Elmowitz, Rutgers University, Entomology Department, Blake Hall, 93 Lipman Drive, New Brunswick, NJ and Albrecht Koppenhöfer,, Rutgers University, Department of Entomology, Blake Hall, 93 Lipman Dr, New Brunswick, NJ.

Physical relocation, as a behavioral response to low temperature, is a plausible survival strategy among invertebrates. The entomopathogenic nematodes (EPN) Steinernema scarabaei and Heterorhabditis bacteriophora occur in temperate habitats and share a close parasitic relationship with two economically important scarab beetle species, the Japanese Beetle (Popillia japonica Newman) and the oriental beetle (Anomala orientalis Waterhouse). To enhance our understanding of how EPN survive seasonal low temperature, change in vertical distribution of S. scarabaei and H. bacteriophora was measured during the 2007 winter season and currently for the 2008 winter season. Continuous field sampling of EPN and respective scarab host species distribution was measured biweekly from late fall to spring warm-up in overlapping sites. Soil temperature at three depths, as well as other meteorological parameters, was recorded throughout the sampling season. Preliminary data suggests the vertical distribution of both EPN species and respective scarab beetle species did change over the winter season. There was a weak correlation between soil temperature and vertical position among respective EPN and scarab host species.

Species 1: Rhabditida Steinernematidae Steinernema scarabaei
Species 2: Rhabditida Steinernematidae Heterorhabditis bacteriophora
Species 3: Coleoptera Scarabaeidae Popillia japonica (Japanese beetle)