Open Journal of Veterinary Medicine, 2012, 2, 124-128
http://dx.doi.org/10.4236/ojvm.2012.23021 Published Online September 2012 (http://www.SciRP.org/journal/ojvm)
Evaluation of Endectocides and Conventional Acaricides in
the Control of the Boophilus microplus on Field-Kept Dairy
Cattle in the State of Pernambuco-Brazil
Vania Lucia Assis Santana1, Maria Aparecida Da Gloria Faustino2, Erika Korinfsky Vanderley2,
Marilene Maria Lima3, Leucio Camara Alves2
1Ministry of Agriculture, Livestock and Food Supply, National Laboratory of Animal and Plant,
Rua Dom Manoel de Medeiros, Recife, Brazil
2Department of Veterinary Medicine, Federal Rural University of Pernambuco, Recife, Brazil
3Academic Unit of Serra Talhada, Federal Rural University of Pernambuco, Serra Talhada, Brazil
Received July 2, 2012; revised July 30, 2012; accepted August 10, 2012
ABSTRACT
The aim of the present study was to evaluate different acaricide treatments for the control of Boophilus microplus on
field-kept dairy cattle in the state of Pernambuco, Brazil. The first phase of the experiment consisted of collecting the
ingurgitated female Boo philus microplus directly from the hosts for attainment of larvae. After the attainment of larvae,
the artificial infestation procedure began on the cattle, with larvae ages ranging from 7 to 14 days. On Day 0, animals
were separated into 12 groups to receive the corresponding treatment: Abamectin; Ivermectin; Ivermectin LA; Amitraz;
Amitraz + Ivermectin; Amitraz + Ivermectin LA; Amitraz + Abamectin; Association (Cypermethrin + Chlorpyrifos +
Citronella); Association + Ivermectin; Association + Ivermectin LA; Association + Abamectin; and Control. Subse-
quent evaluations were made on post-treatment days +7, +14, +21, +28, +35, +42, +49, +56 and +63. Analyzing the
post-treatment effectiveness per day, indices revealed considerable variation ranging from 0% to 96.63%. Such indices
demonstrate the significant reduction in the number of ticks on the animals in some groups, especially in the Abamectin
group. The analysis of the results demonstrates that the use of different avermectines can assist in the development of
Boophilus microplus control programs, thereby reducing the number of acaricide applications and production costs re-
lated to ticks.
Keywords: Boophilus microplus; Tick; Carrapaticide; Efficiency; Resistance
1. Introduction
The control of the tick Boophilus microplus includes the
systematic use of acaricide products on cattle, which has
had diverse consequences for the animal as well as for
livestock farmers and the tick itself. Jonsson [1] states
that even when losses are controlled, there are costs in-
volving chemicals, labor and equipment as well as pro-
duction losses associated to the treatment and the cost of
restricting access of the animals to determined areas.
While the effective control of the tick seems to be a so-
cioeconomic necessity for farmers, the environmental ef-
fects generated by such products are often not considered
and such effects on non-targeted organisms vary from
product to product [2].
Along with the problem of resistance, other factors
limit the effectiveness of acaricides, such as the method
of preparation and application of the product as well as
the time and frequency of treatment. Solution preparation
can be considered one of the most important phases in
the use of products aimed at killing ticks [1,3].
The use of endectocides thus becomes in an additional
alternative for controlling resistant ticks along with for-
mularizations of prolonged action, which have recently
been launched in the market [4]. The aim of the present
work was to evaluate different acaricide treatments for
the control of Boophilus microplus on field-kept dairy
cattle in the state of Pernambuco, Brazil.
2. Materials and Methods
The present study was carried out on the farm of the Ex-
perimental Station of the Agriculture and Livestock Re-
search Institute, located in the city of São Bento of Una,
Pernambuco, using Holstein cattle. Female cattle in the re-
productive phase were used, weighing an average of 600
kg and totaling 66 animals. The animals fed on grass
(grass native and Brachiaria), also receiving a mineral sup-
C
opyright © 2012 SciRes. OJVM

V. L. A. SANTANA ET AL. 125
plement twice a day, mesquite and the fodder plant Pen-
nisetum purpureum with palm leaves and sugarcane leaves.
The first phase of the experiment consisted of collect-
ing the ingurgitated female Boophilus microplus directly
from the hosts for attainment of larvae. Specimens were
sent to the Laboratory of Parasitic Diseases in Domesti-
cated Animals of the Department of Medicine Veterinary
at the UFRPE, where they were cleaned, placed in Petri
dishes and kept at room temperature (25˚C to 31˚C; rela-
tive humidity above 70%) in the laboratory. After the
attainment of larvae, the artificial infestation procedure
began on the cattle, with larvae ages ranging from 7 to 14
days. For such, the animals were duly contained and the
larvae deposited along the dorsal line, placing about 2500
larvae per animal 21 days prior to treatment (Day −21);
the procedure was repeated on Day −14 and Day −7.
On Day 0 (day of treatment), the animals were sepa-
rated into groups, each composed of 04 (four) to 08
(eight) animals under the same sanitary and feeding con-
ditions, selected non-probabilistically by convenience for
the formation of the following experimental groups:
Group I: Abamectin1 (08 animals)
Group II: Ivermectin1 (08 animals)
Group III: Ivermectin LA1 (08 animals)
Group IV: Amitraz (05 animals)
Group V: Amitraz + Ivermectin (06 animals)
Group VI: Amitraz +Ivermectin LA (04 animals)
Group VII: Amitraz + Abamectin (05 animals)
Group VIII: Association2 (04 animals)
Group IX: Association + Ivermectin (04 animals)
Group X: Association + Ivermectin LA (04 animals)
Group XI: Association + Abamectin (05 animals)
Group XII: Control (04 animals)
The initial degree of infestation of the animals was
measured, counting the number of females with a diame-
ter ≥4 mm [5] on the left side of the animal and recording
the results.
The experimental groups then received the corresponding
treatment. Products were applied following the manufac-
turers’ instructions. For the control group, the only proce-
dure carried out was the tick count. Subsequent evalua-
tions were made on post-treatment Days +7, +14, +21,
+28, +35, +42, +49, +56 and +63.
The final effectiveness of the treatments was calcu-
lated by post-treatment Day 56, using the following equ-
ation [6]:
100
ab
a


treatment groups, the F test (ANOVA) was used and
3. Results and Discussion
ll tick instars was evi-
ed
am
tudy of the animals revealed differ-
en
effectiveness on
D
of treatment. The administration of abamectin together
E
where
E = Therapeutic effectiveness
a = Average number of ticks in the group control
b = Average number of ticks in the treated group
For the determination of statistical differences between
paired comparisons were evaluated using the Tukey test.
The level of statistical significance was set at 5.0%. The
Statistical Package for Social Sciences (version 11) was
used for the calculations.
On Day 0, high infestation for a
denced, with a predominance of females. The arithmetic
average of the number of ticks ranged from 136 to
370.75, oscillating in all groups treated in the period
from 7 to 63 days following treatment. Table 1 displays
the average number and standard deviation of the number
of ticks per day analyzed. With the exception of the
groups treated with the Association and the group control,
there was a reduction in counts from Day 0 to Day +7.
On Day +7, the lowest averages of ticks occurr
ong the Amitraz + Abamectin (33.00), Abamectin
(30.13), Amitraz + Ivermectin (41.33) and Amitraz +
Ivermectin LA (46.25) groups. The Tukey test for paired
comparisons revealed significant differences between
treatments, except on Days 0 and 63. The analysis of the
effectiveness of the groups per post-treatment day (Table
2) revealed that indices obtained a great variation (0% -
96.63%), reaching considerable values of effectiveness.
Such indices revealed the reduction in the number of
ticks on the animals. However, the effectiveness of the
treatments can better be evaluated by analyzing the ani-
mals individually.
The individual s
ces in the behavior of the infestations by the tick; some
animals exhibited more or less parasites than others in
the same treatment group, demonstrating the resistance
of the host to tick attacks, consisting of the optimum
method of non-chemical control of the tick, as cited by
Jonsson et al. [7]. Animals with a predominantly white
hide exhibited greater resistance to ticks that those with a
predominance of black; this fact was previously reported
by Oliveira and Alencar [8] and Teodoro et al. [9]. The
control group exhibited increasing levels of tick infesta-
tion and was submitted to treatment on Day +56. Lacking
a control group thereafter, the effectiveness of the other
groups was not calculated on Day +63.
Abamectin presented good levels of
ays +7, +14 and +21, with average indices of 88.78%,
79% and 84.01%, respectively, which were higher than
the indices of standard ivermectin and ivermectin LA.
Constancy in the effectiveness of treatments on the ani-
mals in the abamectin group is evident and the animals
from this group were the only ones that did not undergo a
repetition of the treatment on Day +28. When abamectin
was associated jointly with amitraz, there was consider-
able effectiveness on Days +7, +14 and +21, but tick
counts were higher on Day +28, which led to a repetition

V. L. A. SANTANA ET AL.
126
philus microplus ticks per treatment group and respective
station.
Table 1. Average and standard deviation of number of Boo
post-treatment days in field-kept cattle at the IPA experimental
Statistic Treatment 0 7 14 21 28 35 42 49 56 63
Average Abamectin 370.30.78.102.188.378.71.75 13 40.25 29.50 88 78.38 75 38 3838
Ivermectin
ermectin LA
309.00
270.63
247. 185. 109. 159. 194.
Iv211. 184. 203. 283.155.
150.
Am
Amitraz + LA 101.
138.
243. 102.
Association
288. 131.
191.279. 342.
(p <0. <0.
Standard Abam
Deviation Iectin 186.217.
v 129.
Am
Amitraz ctin LA
210. 213.
Association 118.103.
Association . LA103.33.
105.
106. 142.
63
63
88
88
25
75
14
29
86
183.57
115.57 83.
117.71 79.
57
43 134.
79.43 242.
33
83
83
Amitraz 227.40 172.4066.60 67.60 162.7590.25 44.50 45.25 2586.25
itraz ectin + Iverm
Ivermectina
260.83
213.25
41.33 62.
46.25 68.
50 78.
75 51.
50
75
47.83 77.
63.75 49.
67 60.
33 41.
67
33
28.33
31.00 65.
144.00
00
123.33
33
Amitraz + Abamectin 153.60 33.00 38.40 36.60 8036.00 64.80 19.25 213.00114.00
Association 225.60
253.25
60
85.25 61.
40
75 51.
62.40
75
253.60
72.50 48.
52.20
00 99.
80.00
25
17.40
82.25
197.60
175.50
103.40
22.50 + Ivermectin
Association + Iverm. LA
Association + Abam.
206.50 60.
282.00 87.
75
60 104.
67.00 106.
80
00
59.60
121.25
20
85.50
44.80
39.75
93.20
41.75 130.
14.25 225.
50
80
65.00
20
Control 136.00 175.0025 184.50 261.755000 373.75 441.5076.75
-value 11)
ectin
0.363
175.44
001
32.27 43.
*0.043
71 11.
*<0.001
65
*0.004
141.79
*<0.001
72.47 99.
*<0.001
73
*001 <0.
170.01
*001
168.50
*0.346
24.41
verm14 142.44110.6242.45 114.92146.0650.60 52.33 38.50 76
I ermectin LA
Amitraz
149.26
144.48
101.88
64.24 60.
134.43
27 35.
20
41
153.77
83.18 23.
83.09
67 24.
47.57
57
25.61
26.59 90.
121.99
86 25.
148.90
20
itraz ectin + Iverm
+ Iverme
137.48
99.54
30.45 53.
15.02 45.
77 45.
33 71.
27
70
56.18 49.
65.76 44.
40 35.
29 36.
37
50
41.63
32.14
132.62
9.17
211.45
36.12
Amitraz + Abamectin 118.14 13.10 28.98 41.62 88.70 25.52 40.12 10.37 102.8884.63
Association
+ Ivermectin
183.18
109.13
12
12.09 40.
65.53 48.
47 15.
96
82
42
27.79 20.
28.90 84.
15
95
46
9.34 175.
45
71
92.02 12.
67.96
04
+ Iverm92.63 35.42 81.55 04137.0554.18 30.77 29 59.90 64.50
Association + Abam.
Control
149.13
70.22
68.60 53.
11
64 31.
77
66
134.79
109.34
79.37 71.
32.56 25.
20 31.
38
59
14.17
24.96 83.
24
48 49.
78.53
98
(*)—Snificant differen; (1)—F tesA
to field-kept cattle at the IPA experimental station per post-treatment day.
igce of 5.0%t (ANOV).
Table 2. Effectiveness of acaridides applied
7 14 21 28 35 42 49 56
Abamectin 8 7 8 6 7 6 4 1 8.789.004.019.861.969.969.604.30
Ivermectin 0 2.81 40.79 39.20 30.28 66.21 77.64 82.01
Iv
65. 37.
Association 0
Am. 76.81.
Am
Association + I.
Association + I
Association + Abam. 49.94 45.20 67.70 0 83.97 72.75 96.63 48.86
ermectin LA 0 3.33 0.00 0.00 34.32 65.58 78.75 69.57
Amitraz 1.49 18 63.36 82 67.71 86.99 77.89 72,03
46.46 66.18 3.11 81.32 76.61 95.34 55.24
itraz + Iverm38 67.32 57.45 73 72.21 82.26 92.42 67.38
itraz + Iverm LA 73.57 64.05 71.95 75.65 82.35 87.92 91.71 85.28
Amitraz + Abam. 81.14 79.92 80.16 46.97 87.12 81.05 94.82 43.71
verm51.29 67.71 66.53 72.30 82.83 70.98 77.99 60.25
verm. LA65.29 64.97 42.55 53.68 69.41 88.38 88.83 70.44

V. L. A. SANTANA ET AL. 127
withciatio anophus/pyr
throidproduce the goolts as
e ots contbamectin and re
also demonstrated
hi
s infesting
th
esults were achieved
ag
tronella, a greater reduction effect in infestations was
obtaIt can rmethistocidbits
long-term effectiveness anoulded irol
projectng contionalcidings. Toma et
is amidine can be used if tick control is
im
4.
d production costs related to ticks infesta-
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the chemical asson orgosphore-
/citronel failed to
her two treatment
e sam
aining a
d resu
th -
quired further treatment on Day +28.
The good performance of abamectin corroborates the
results of Bridi et al. [10], who, in comparing the appli-
cation of abamectin with ivermectin,
gher degrees of effectiveness with abamectin, which
performed better than ivermectin, as in the present study.
Comparing the action of four endectocides on Boophilus
microplus infestations, Alves-Branco et al. [11] found
considerable degrees of effectiveness with abamectin of
74.30% by the 35th day, obtaining the highest rate on Day
+21. However, these authors obtained a “knock down”
effect on Day 4, with a rate of 85.80%, superior to the
other endectocides tested. Thus, abamectin can be rec-
ommended for the control of the Boophilus microplus in
naturally infected cattle during periods of intense para-
sitic infestation, allowing animal handlers to obtain ade-
quate levels of protection for their animals.
Ivermectin only exhibited a certain level of effective-
ness on Day +21 (40.79%), which was not sufficient for
a significant reduction in the number of tick
e animals and a further application of this endectocide
was required on Day +28. However, in the individual
analysis of the animals from this group, a satisfactory
degree of effectiveness was observed in two animals
(78.98% and 96.17%) on Day +28. The indices found in
the present study for ivermectin differ from those found
by Marques et al. [12], who obtained 100% effectiveness
on Day +8. In associating ivermectin with conventional
acaricides, better effectiveness of the treatments was
evidenced. The data presented here may reveal the de-
velopment of resistance to this endectocide in the Boophi-
lus microplus sample. Confirmative “in vitro” tests are
necessary to determine this. The resistance of this ixodi-
dae to ivermectin has been described by Martins & Fur-
long [13] and Sabatini et al. [14].
Bovines medicated with ivermectin LA also exhibited
wide variation in effectiveness, requiring repetition of
treatment on Day +28, as no effective r
ainst Boophilus microplus. The degree of effectiveness
from Day +7 to Day +42 was less than 70%, thereby dif-
fering from results found by Silva and Marra [15] in the
state of Minas Gerais, who obtained levels above 90% on
post-treatment Days 7, 14 and 21. In the city of Candiota,
RS, Alves-Branco et al. [16] obtained an 86.18% degree
of effectiveness on Day +4, with a therapeutic average of
94.8% from Day +7 to Day +28. Carvalho et al. [17],
however, obtained lower tick counts from Day +14 to
Day +84 using this product. When ivermectin LA was
associated to acaricide baths with amitraz or the synthetic
chemical association organophosphorus/pyrethroid/ci-
al. [18] suggest a strategic spraying program with the
application of endectocides on properties with a high
degree of infestation. The authors also state that the tick
control program should be adapted to each case, increas-
Emb
ined. be affid that endece exhi
d sh
acari
be us
e spray
n cont
s usiven
ing the intervals between treatments as the parasitic load
diminishes.
It is important to verify the results with the use of ami-
traz, as there was a significant reduction of the number of
ticks on Day +7 and the treatment became more effective
as the study elapsed, especially when associated with the
endectocides. Post-treatment effectiveness ranged from
0% to 93.85% in the different animals. The treatment
revealed that th
plemented adequately, thereby prolonging the effec-
tive life of this acaricide.
The association group only produced satisfactory re-
sults after a second application of the treatment on Day
+28. A reduction in infestation was observed on Day +35,
with degrees of effectiveness above 81.32%. This treat-
ment had a better performance when associated with en-
dectocides.
Conclusion
The analysis of the results from the present study de-
monstrates that the use of different avermectines can
assist in the development of Boophilus microplus control
programs, thereby reducing the number of acaricide ap-
plications an
tions.
5. Acknowledgements
We are thankful to Institute of Research in Animal and
Plant of Pernambuco, Brazil, for providing the study fa-
cilities to complete this research.
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