ARS | Publication request: Directional movement of entomopathogenic nematodes in response to electrical current

Submitted to: Society for Invertebrate Pathology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 8, 2009
Publication Date: August 1, 2009
Citation: Shapiro Ilan, D.I., Campbell, J.F., Lewis, E.E., Kim-Shapiro, D.B. 2009. Directional movement of entomopathogenic nematodes in response to electrical current [abstract]. 42nd Annual Meeting of Society for Invertebrate Pathology, August 16-21, 2009, Park City, Utah. Available: http//www.sipweb.org/pastmeetingsip.cfm

Interpretive Summary: Beneficial insect-killing nematodes are safe environmentally friendly natural insecticides. To maximize pest control efficacy, it is important to understand the basic biology of these nematodes. ARS scientists from the Southeastern Fruit and Tree Nut Research lab, Byron, Georgia in cooperation with ARS scientists in Manhattan, Kansas, the University of California, Davis, and Wake Forest University, have been investigating the basis for how nematodes find an insect pest to infect in the soil. The researchers discovered that the nematodes respond to small electrical currents; this may be one way that the nematodes cue into their host or their host’s habitat. Identification of factors that affect nematode infection and host-finding leads to enhanced insect suppression.

Technical Abstract: Entomopathogenic nematodes in the genera Steinernema and Heterorhabditis are important regulating agents of insect populations. The infective juvenile nematodes respond to a variety of stimuli that aid in survival and host finding. Identification of novel cues in the nematodes’ environment can help us understand their basic ecology and enhance biocontrol efforts. We measured directional movement in response to an electrical current in five steinernematids (S. carpocapsae, S. feltiae, S. glaseri, S. riobrave, and S. siamkayai) and four heterorhabditids (H. bacteriophora, H. indica, H. georgiana, and H. megidis). None of the heterorhabditid species responded directionally to the electrical current except H. georgiana, which moved to a higher electrical potential. In contrast, all of the steinernematids responded directionally to the electrical field. Differential movement among the steinernematids species tended to reflect foraging strategy. Thus, we hypothesize that entomopathogenic nematodes (primarily steinernematids) detect electrical currents or electromagnetic fields in nature, and these stimuli may be used differentially among species for host finding or enhancing other fitness characters.