Acaricides for eradication of the tick Amblyomma variegatum in the Caribbean

Abstract

The success of an eradication campaign against the trepical bont tickin the Caribbean imposes the use of active acaricide compounds, if possible with residual activity, easy to apply and requiring few or noaccessible water supplies and expensive application equipment. Testsof in vitro susceptibility of tick strains from Puerto Rico andGuadeloupe as well as observations of the impact of the current tickcontrol campaigns conducted in some Caribbean islands, seem toindicate that there is no problem of resistance to acaricides.Pyrethroid acaricides have an advantage since they are active at verylow concentration levels and have a low toxicity for mammals and tothe environment. Some of them are in a pour-on formulation whichallows for rapid application and complete coverage of the whole bodyof the animal. A withdrawal period is not necessary. However, impro-vements must be found to facilitate the application onto the back ofcattle that, for the majority in the Caribbean, are tethered and notperfectly restrained. A spot-on application method with a drench gunseems more adapted to tethered animals than the pour-on. For smallruminants and dogs but also for cattle, slow release devices impre-gnated with acaricides may be useful in reducing the frequency ofanimal treatments. However, experiments on goats with collarsimpregnated with flumethrin indicate an efficiency of less than55 days, insufficient to justify their use on a large scale in an eradica-tion program.