Eh. Ahrens et al., MICROENCAPSULATED PERMETHRIN FOR CONTROLLING BOOPHILUS-MICROPLUS ON CATTLE IN SOUTH TEXAS, The Southwestern entomologist, 23(1), 1998, pp. 25-30
A study was conducted at the USDA-ARS, Cattle Fever Tick Research Labo
ratory, Mission, Texas, to determine the efficacy of a 0.05 and 0.1% m
icroencapsulated permethrin formulation applied as a whole-body spray,
in a standard dip vat, and in a laboratory bioassay against Boophilus
microplus (Canestrini) on cattle. An additional study was conducted o
n the King Ranch in Kleberg County, Texas, to determine the stability
of 0.05% microencapsulated permethrin formulation in a dip vat under S
outh Texas conditions. Cattle were infested with all parasitic life st
ages of B. microplus and were sprayed or dipped with a concentration o
f 0.05 and 0.1% microencapsulated permethrin. As determined by the ind
ex of reproduction, the 0.05 and 0.1% whole-body spray treatments prov
ided 85.8 and 96.2% control, respectively, and the 0.05 and 0.1% dip v
at treatment provided 98.2 and 99.3% control, respectively. Laboratory
bioassay results compared favorably with those obtained with the spra
y and dip vat treatment. The microencapsulated permethrin remained sta
ble in the ranch vat for three to four weeks. After four weeks, the va
t solution began turning black and became foul, apparently due to bact
erial growth. In addition, the microencapsulated permethrin became ver
y difficult to resuspend.