Efficacy of entomopathogenic nematodes for larval cattle fever tick control

Authors: HINOJOSA JR, ROMEL - University Of Texas Rio Grande Valley; Maestas, Lauren; MAESTAS, SARAH - University Of Texas Rio Grande Valley

Submitted to: Subtropical Agriculture and Environments
Publication Type: Proceedings
Publication Acceptance Date: 2/27/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Rhipicephalus microplus and R. annulatus are pests of livestock and transmit the agents of bovine babesiosis, pathogens that have severe economic impacts on the livestock industry world-wide. Although the range of this tick within the U.S. has been restricted to south Texas by ongoing eradication efforts, pesticide resistance and the availability of unregulated wildlife hosts complicate management efforts. Biological control methods are being investigated as an option to aid in the management of cattle fever tick populations. This study examined the effect of different arthropod killing nematode species on the mortality of R. microplus larvae. Larval ticks (babies) were exposed to 7 different nematode treatments consisting of four nematode species, Steinernema feltiae, Steinernema carpocapsae, Steinernema krausei, and Steinernema riobrave acquired from two different commercial sources. Bioassays were conducted in dishes lined with filter paper, to which each nematode treatment in a water carrier solution was applied. Tick larvae survival was evaluated at day eight and day 14 post-treatment. The day eight mean mortality for each nematode species from the two sources was 71-75% for S. carpocapsae, 28-60% for S. feltiae, and 49-74% for S. riobrave. Treatment with S. krausei, which was only available from one source, resulted in 90% mortality. Some variation in mortality at day 14 was noted when compared to day eight. This experiment will be repeated using a lower volume of carrier solution for nematode application.

Technical Abstract: Rhipicephalus microplus and R. annulatus are significant pests of livestock and vectors of bovine babesiosis that have severe economic impacts on the livestock industry world-wide. Although the range of this tick within the U.S. has been restricted to south Texas by ongoing eradication efforts, pesticide resistance development and the availability of wildlife hosts complicate management efforts. Biological control methods are being investigated as an option to aid in the management of cattle fever tick populations. This study examined the effect of different entomopathogenic nematode species on the mortality of R. microplus larvae. Larval ticks were exposed to 7 different nematode treatments consisting of four nematode species, Steinernema feltiae, Steinernema carpocapsae, Steinernema krausei, and Steinernema riobrave acquired from two different commercial sources. Bioassays were conducted in petri dishes lined with filter paper, to which each nematode treatment in a water carrier solution was applied. Tick larvae survival was evaluated at day eight and day 14 post-treatment. The day eight mean mortality for each nematode species from the two sources was 71-75% for S. carpocapsae, 28-60% for S. feltiae, and 49-74% for S. riobrave. Treatment with S. krausei, which was only available from one source, resulted in 90% mortality. Some variation in mortality at day 14 was noted when compared to day eight. This experiment will be repeated using a lower volume of carrier solution for nematode application.