Comparative effectiveness of coumaphos treatments applied by different methods for the control of Boophilus microplus (Acari: Ixodidae)

摘要

abstract_textpEffectiveness of coumaphos applied by three different treatment methods (dipping vat, spray-dip, and power spray) to cattle infested with parasitic stages (adult, nymphal, and larval) of Boophilus microplus (Canestrini) was studied. Both the number of ticks per calf and the index of reproduction (IR) of engorged females recovered from untreated calves were significantly higher (P 0.05) than from treated calves, regardless of the developmental stage of the ticks or the method of applying the acaricide, indicating that coumaphos had a dramatic adverse effect on ticks. When adult ticks were subjected to the dipping vat method of treatment, both the number of females recovered (54 ticks/calf) and the IR (0.0) were significantly lower (P 0.05) than those of adult ticks subjected to spray-dip (146 ticks/calf; IR = 118,253) or power spray treatments (199 ticks/calf; IR = 289,198). The trend was repeated in ticks that were in the nymphal stage at the time of treatment, indicating that the dipping vat method (1 tick/calf; IR = 0.0) was more effective than either the spray-dip (54 ticks/calf; IR = 38,014) or power spray treatments (96 ticks/calf; IR = 115,945). Likewise, the dipping vat method was more effective (0 ticks/calf; IR = 0.0) than the spray-dip (23 ticks/calf IR = 7,426) or the power spray (57 ticks/calf; IR = 23,848) when ticks were in the larval stage of development at the time treatments were applied. Although all three treatment methods were successful, the dipping vat method reduced tick numbers and reproduction more effectively than spray-dip or power spray. Because the objective of any eradication program is the complete elimination of ticks, treatment in a dipping vat would be the most desirable method./p/abstract_text