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

Abstract

A remotely activated field sprayer was developed for application of the entomopathogenic nematode, Steinerne-ma riobrave (Cabanillas, Poinar, and Raulston) for eradication of the southern cattle fever tick, Rhipicephalus microplus (Canestrini) infesting free-ranging nilgai (Boselaphus tragocamelus) in South Texas. The battery pow-ered 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. Several types of aeria-tion, agitation, and cooling were tested to prolong the viability of the nematodes in water. Continuous aeration extended the longevity of S. riobrave to more than two weeks as compared to cooling or intermittent agitation. The potential use of nematodes pathogenic to R. microplus dispensed by the remotely activated sprayer to infested nil-gai, and potentially white-tailed deer (Odocoileus virginianus), as part of integrated cattle fever tick eradication efforts is discussed