Development of a remotely activated field sprayer and evaluation of temperature and aeration on the longevity of Steinernema riobrave entomopathogenic nematodes for treatment of cattle fever tick infested nilgai

Authors: Goolsby, John; CANTU, DIANA - University Of Texas Rio Grande Valley; RACELIS, ALEXIS - University Of Texas Rio Grande Valley; VASQUEZ, ALEJANDRO - University Of Texas Rio Grande Valley; Hoffmann, Wesley; Shapiro Ilan, David; HINOJOSA, JOSE - Animal And Plant Health Inspection Service (APHIS); BONILLA, DENISE - Animal And Plant Health Inspection Service (APHIS); ELLIS, DEE - Texas Agrilife; Perez De Leon, Adalberto - Beto

Submitted to: Subtropical Agriculture and Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2019
Publication Date: 7/7/2019
Citation: Goolsby, J., Cantu, D., Racelis, A., Vasquez, A., Hoffmann, W.C., Shapiro Ilan, D.I., Hinojosa, J., Bonilla, D., Ellis, D., Perez De Leon, A.A. 2019. Development of a remotely activated field sprayer and evaluation of temperature and aeration on the longevity of Steinernema riobrave entomopathogenic nematodes for treatment of cattle fever tick infested nilgai. Subtropical Agriculture and Environments. 70:1-5.

Interpretive Summary: Cattle fever ticks (CFT) Rhipicephalus (=Boophilus) microplus and Rhipicephalus annulatus are invasive livestock pests that are endemic to Mexico and invasive along the Texas – Mexico border. Acaricide resistance, alternate wildlife hosts, and pathogenic landscape forming weeds present challenges for sustainable eradication of this pest in the U.S. CFT are the vector for bovine babesiosis, a lethal disease causing high mortality particularly in susceptible European breeds of cattle and severely affecting the beef cattle industry. Efforts to eradicate CFT from the United States have been successful; however, a permanent quarantine zone (PQZ) is maintained between Texas and Mexico to prevent incursions of CFT from wildlife and stray cattle. In recent years, there has been an increase in CFT infestations outside of the PQZ in Texas. One of the alternate wildlife hosts for CFT in South Texas are nilgai (Boselaphus tragocamelus), an exotic Asian antelope. Nilgai are highly mobile with large home ranges and are implicated in the spread of CFT, through the landscape. Currently, there are no methods for control of CFT on nilgai other than culling. Insect and tick killing parasitic round worms (entomopathogenic nematodes) are under evaluation for eradication of CFT on nilgai. Nematodes would be applied as a water-based spray to nilgai as they move through fence crossings and use latrines. A remotely activated field sprayer was developed for application of nematodes on CFT infested nilgai. The details of the sprayer are given in this paper. This paper also explored the effect of temperature, aeration and agitation on survival of nematodes in the sprayer tank.

Technical Abstract: A remotely activated field sprayer was developed for application of the entomopathogenic nematode, Steinernema riobrave (Cabanillas, Poinar, and Raulston) for eradication of the southern cattle fever tick, Rhipicephalus microplus (Canestrini) on free-ranging nilgai antelope in South Texas. The battery powered sprayer is activated by sonic sensors that detect movement of nilgai through fence crossings. An onboard computer operates the sprayer pump and aerator that oxygenates the solution of nematodes. This study tested several types of aeriation, agitation, and cooling to prolong the viability of the nematodes in water. We found that continuous aeration extended the longevity of S. riobrave to more than two weeks as compared to cooling or intermittent agitation.