Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 6, 1999
Publication Date: N/A
Interpretive Summary: Ticks cause high economic losses due to the cost of acaricidal treatment, their ability to transmit diseases to man and animals, as well as through direct damage to hosts resulting from blood loss and irritation from biting. Significant economic loss and illness results from the activities of the man-biting tick, Ixodes scapularis, which transmits the etiological agent which causes Lyme disease, Borrelia bergdorferi, as well as a number of other serious pathogens. Although acaricides are commercially available for use in the control of I. scapularis, concerns about the environmental impact and safety of the use of such chemical compounds has limited their use by the public. Entomopathogenic nematodes of the genus Steinernema are promising biological control agents for a number of economically important insect pests, and have been shown to kill replete I. scapularis females in vitro. Steinernema riobravis (355 and Osca) in field trials killed 93 and 100%, respectively, of replete I. scapularis ticks.
We have tested and compared the efficacy of 2 exotic variants of Steinernema riobravis (355 and Osca), originally isolated from the Rio Grande Valley, against replete female black-legged ticks, Ixodes scapularis. In field trials conducted on the ARS research station in Beltsville , Maryland, wooden box plots (1m2) were established along the meadow/woodland interface. The plots were seeded with 10 replete female I. scapularis, and the plots were sprayed with 1 x 105, 5 x 105, or 1 x 106 S. riobravis 355 or Osca. S. riobravis 355 and Osca were both highly pathogenic to I. scapularis replete females, resulting in killing within 5 days of 93 and 100%, respectively, in plots treated with 1 x 106 nematodes. Weekly testing of soil samples using Galleria mellonella larvae as sentinel hosts revealed that the nematodes persisted in the soil for at least 6 weeks after the initial applications.