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

Authors: Gulzar, Sehrish; TERRILL, THOMAS - Fort Valley State University; SIDDIQUE, AFTAB - Fort Valley State University; Burke, Joan; Shapiro Ilan, David

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2025
Publication Date: 8/6/2025
Citation: Gulzar, S., Terrill, T., Siddique, A., Burke, J.M., Shapiro Ilan, D.I. 2025. Relative virulence, host finding ability, and reproductive capacity of entomopathogenic nematodes for control of the goat biting louse Bovicola caprae (Phthiraptera: Trichodectidae). Veterinary Parasitology. 339. https://doi.org/10.1016/j.vetpar.2025.110572.
DOI: https://doi.org/10.1016/j.vetpar.2025.110572

Interpretive Summary: The goat biting louse is a significant pest of goats. The lice can cause anemia and weight loss thereby reducing productivity. Chemical insecticides are used to control the lice. However, due to the development of pesticide resistance and environmental concerns, alternative methods are needed. Beneficial nematodes (also called entomopathogenic nematodes) are small round worms that kill insect pests without harming humans or the environment. Our goal was to test the ability of different beneficial nematode species to kill and reproduce in the goat lice under laboratory conditions. Our results indicated that beneficial nematodes can kill goat lice. The most virulent (best) nematodes for killing goat lice that we tested are called Steinernema riobrave and S. carpocapsae. Steinernema riobrave was also the best at reproducing inside the lice. Our findings indicate that beneficial nematodes may be a safe and effective method to control goat lice. Future research is needed to test the approach under field conditions.

Technical Abstract: Bovicola caprae (Phthiraptera: Trichodectidae), the goat biting louse, is a permanent, obligate ectoparasite of goats. It causes irritation, dermatitis, hypersensitivity, anemia, body weight loss and lower productivity in goats. Conventionally, various insecticides have been used to control the lice. Development of insecticide resistance, environmental concerns, and limitations of chemical pesticides in organic systems indicate that alternative methods of control are needed, such as biological control. The objective of this study was to investigate the relative potential of different entomopathogenic nematode (EPN) species as biocontrol agents against B. caprae. Five EPN species, Steinernema carpocapsae, S. feltiae, S. riobrave, Heterorhabditis bacteriophora and H. indica were tested. In laboratory experiments, we measured relative EPN host attraction, virulence and reproductive capacity. Results indicated that all the EPNs were attracted towards the lice. All EPNs tested infected and killed adult lice; however, lice survival was dependent on EPN species, EPN rates and exposure time. After 48 hours, the lowest B. caprae survival was observed in S. riobrave and S. carpocapsae . In the reproduction assay, greater numbers of infective juveniles were produced in the S. riobrave treatment followed by S. carpocapsae, H. bacteriophora and H. indica. This study concludes that EPNs have ability to invade and kill the lice, with S. riobrave and S. carpocapsae being likely to be more effective against B. caprae than the other EPNs tested. Future study may explore the use of EPNs against B. caprae in live animal applications.