Relative virulence, host finding ability, and reproductive capacity of entomopathogenic nematodes for control of the goat biting louse Bovicola caprae (Phthiraptera: Trichodectidae).

Bovicola caprae, the goat biting louse, is a permanent, obligate ectoparasite of goats. It causes dermatitis, irritation, hypersensitivity and lower productivity in goats. Problems associated with chemical insecticide use such as insecticide resistance and environmental concerns indicate that alternative methods (e.g., biological control) are needed. The objective of this study was to investigate the relative potential of different entomopathogenic nematode (EPN) species to control B. caprae. Five EPN species, Steinernema carpocapsae, S. feltiae, S. riobrave, Heterorhabditis bacteriophora and H. indica were tested in the laboratory. We measured relative EPN host attraction, virulence and reproductive capacity. A series of application rates were used to measure EPN virulence. Infective juvenile (IJ) reproduction was assessed in lice cadavers. Results indicated that all the EPNs tested were attracted, infected and killed adult lice; however, louse survival was dependent on EPN species, rate and exposure time. After 48 h, the lowest B. caprae survival was observed in S. riobrave and S. carpocapsae at 200 IJs/insect, with H. bacteriophora and H. indica exhibiting intermediate levels of virulence. In the reproduction assay, greater numbers of IJs were produced in the S. riobrave treatment followed by S. carpocapsae, H. bacteriophora and H. indica. No IJs were found in S. feltiae treated lice. In conclusion, EPNs can invade and kill B. caprae, with S. riobrave and S. carpocapsae exhibiting the most promise for biocontrol efficacy. Future studies will explore the use of EPNs against B. caprae in live animal applications.