Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 10, 1996
Publication Date: N/A
Interpretive Summary: Three methods used in U.S. Tick Eradication programs for applying pesticide to livestock are immersion in a dipping vat, treatment in a portable device called a spray-dip machine, or treatment with a power sprayer. Unfortunately, there are no data to prove which of these methods is the most effective for applying a pesticide to tick-infested cattle. Because the objective of the eradication program is the elimination of cattle ticks as quickly as possible after an outbreak is detected, it is important to know if all the methods for applying a pesticide are equally effective. Results of the experiment showed that while all three methods of pesticide application were highly effective (>95% control), only the dipping vat method provided 100% control. The offspring from the small numbers of engorged females that survived on cattle after they were treated with spray-dip and power spray equipment could hinder the efforts of a tick eradication program.
Technical Abstract: Effectiveness of coumaphos applied by three different treatment methods (dipping vat, spray-dip, and power spray) to cattle infested with all parasitic stages (adult, nymph, and larva) of Boophilus microplus (Canestrini) was studied. Control of engorged female ticks subjected to the dipping vat method of treatment was higher (100%) than adults subjected to power spray treatment (95.7%), while control using spray-dip equipment was intermediate (98.3%). Fewer larvae subsequently reached repletion in the dipping vat treatment (0 ticks per animal) than larvae treated by power spray application (57 ticks per animal). Detachment, oviposition, and egg viability associated with surviving females in each treatment indicated that ticks treated by power spray or spray-dip continued to survive to repletion for 22 days after treatment. Furthermore, oviposition and egg viability occurred for 15-17 days after treatments were applied. In contrast, ticks that were dipped survived for only 6 days after treatment and none of the females lived to oviposit. All three methods of coumaphos treatment provided a high level of control (>95%). However, there was clear evidence that treatment in a dipping vat was the most effective method of eliminating ticks and preventing reproduction in the shortest period of time after treatments were applied.