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Title: Effect of Steinernema glaseri-infected host exudates on movement of conspecific infective juveniles

Author
item Kunkel, Brian
item Shapiro Ilan, David
item Campbell, James - Jim
item LEWIS, E - UC DAVIS, CA

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2006
Publication Date: 9/1/2006
Citation: Kunkel, B.A., Shapiro Ilan, D.I., Campbell, J.F., Lewis, E.E. 2006. Effect of Steinernema glaseri-infected host exudates on movement of conspecific infective juveniles. Journal of Invertebrate Pathology. 93:42-49.

Interpretive Summary: Entomopathogenic nematodes are round worms that cause lethal infections in many different insect pests. Immature nematodes invade insects, resume development, and locate mates. Some nematodes use odors emitted by living insects to locate them. There have been many studies that look at how live insects attract nematodes, but not many that look at how previously nematode infected insects affect other nematodes. We examined how the accumulated odors from infected insects and odors from infected insects at discrete time periods affected other nematodes. Odors from infected insects did not attract or repel other nematodes for 48 hours. After 48 hours, nematodes generally were repelled from odors that seeped out of nematode infected insects. These odors may help other nematodes identify insects suitable for invasion. This research helps us understand why nematodes infect particular hosts, and will help us utilize these natural enemies more effectively in biological control programs.

Technical Abstract: Entomopathogenic nematodes that invade a host develop and achieve reproductive success, or they die. Cruiser nematodes like Steinernema glaseri use host-associated cues to locate hosts. Many studies have examined nematode attraction to cues from uninfected hosts, but little information exists about the effect cues from infected hosts have on nematodes. We investigated how exudates from nematode-infected hosts affect the behavior of S. glaseri infective juveniles. We hypothesized that the infective juvenile’s behavioral response to infected hosts changes as the infection advanced. We examined the effect of accumulated exudates, and exudates from discrete intervals, on infective juvenile movement behavior. As the infection progressed, infective juveniles responded differently to infected host exudates. We detected no effects on nematode repulsion or attraction from exudates produced within the first 48 h post-infection. We observed repulsion from cadaver exudates beginning at 48 h. The repelling effect generally continued in remaining sampled intervals (through 162 h). The repellent effect of infected host exudates may aid the infective juvenile’s ability to discriminate between suitable and unsuitable hosts.