Monday, December 10, 2007 - 10:53 AM

Habitat complexity effects on entomopathogenic nematode dispersal

Randa Jabbour,, Pennsylvania State University, Interdepartmental Graduate Degree Program in Ecology, 521 ASI Bldg, University Park, PA, Mary Barbercheck,, Pennsylvania State University, Entomology, 516 ASI Bldg, University park, PA, Alyssa Gendron,, Pennsylvania State University, 501 ASI Bldg, University Park, PA, and Brosi Bradley,, Juniata College, Biology Department, 1700 Moore Street, Huntigdon, PA.

Habitat heterogeneity in agriculture is critical for conservation of beneficial organisms. Refuge habitats have been shown to enhance activity of aboveground biological control agents. Such habitats may increase survival and dispersal of soil-dwelling agents as well, although this has rarely been examined in field experiments. We tested the effect of habitat complexity on the dispersal of entomopathogenic nematodes (EPN), soil-dwelling insect pathogens currently used as a biological control agent of lepidopteran, coleopteran, and dipteran pests in agricultural systems. We compared the effect of simple (crop) and more complex (crop plus refuge) habitats on the persistence and movement of EPN applied to soil in a maize field. The experiment was conducted in 2005 and 2006. We quantified EPN dispersal by bioassay of soil samples collected at several distances away from the EPN application point in both habitat types and surrounding crop area. We detected EPN as far as 3m away from the source 9 days after application. In 2005, greater EPN movement occurred within complex habitats than in simple habitats. In 2006, EPN movement was similar in both habitats. This result may be due to the comparable plant density and soil moisture in both habitats, in contrast to differences in these variables in 2005. The results indicate that EPN movement is not necessarily dependent on plant diversity, but may respond to variation in plant density, and subsequently, soil moisture. Complex habitats may serve as movement corridors for EPN, depending on the contrast between the refuge and crop area.

Species 1: Rhabditida Steinernematidae Steinernema carpocapsae