Efficacy of entomopathogenic nematodes for larval cattle fever tick control

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

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/30/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Bovine babesiosis is a vector-borne disease transmitted by cattle fever ticks that threatens the health of cattle and can have severe economic impacts on the livestock industry. Wildlife hosts like nilgai antelope and white-tailed deer play a role in the maintenance of populations of cattle fever ticks in south Texas. Due to concerns about pesticide resistance development and the environmental impacts of chemical insecticides, more environmentally sound methods for biological control methods are needed to manage cattle fever tick populations. We carried out a study to examine the effect of different arthropod killing nematode species on the mortality of first stage cattle fever ticks.First stage immature 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 approximately six mL of 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: Bovine babesiosis is a vector-borne disease transmitted by Rhipicephalus (Boophilus) microplus and R. (B.) annulatus that threatens the health of cattle and can have severe economic impacts for the livestock industry. Wildlife hosts like nilgai antelope and white-tailed deer play a role in the maintenance of populations of cattle fever ticks within the permanent quarantine zone in south Texas. Due to concerns about pesticide resistance development and the environmental impacts of chemical insecticides, biological control methods are being investigated to manage cattle fever tick populations. We carried out a study to examine the effect of different entomopathogenic nematode species on the mortality of R. (B.) 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 approximately six mL of 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.