A method for testing the value of chemical mixtures as repellents of the Gulf Coast tick

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Title:
A method for testing the value of chemical mixtures as repellents of the Gulf Coast tick
Physical Description:
Mixed Material
Creator:
Brody, Arthur L
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine ( Washington, D.C )
Publication Date:

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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030345394
oclc - 781634751
System ID:
AA00017460:00001


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Full Text
October 1959


United States Department of Agriculture
Bureau of Entomology and Plant Q,.arantine


A METHOD FOR TESTING THE VALUE OF CHE,'TCAL MIXTURE.:)
AS REPELLENTS OF THE GULF C'.';*T TICK

By Ar.'.' r L. Brody, Division of Insects Aff. ti.T,' .on a .l A;,im3als*



S'u-'ies on repellents of the ._ilf 1>3st tick (,:k -.',_r_,.,
T.lLC,-!L ti. Koch) have been conducted at the Vald',hi, Ga., lab-
oratory of this Bureau for some time. These studies, conducted by
H. Hl:.,;i' aind later by H. M. Brundrett, were wholly field experi-
n.e:nts on either animals at the Government c:;-..rimental fc:." at
Vald:-ia, or on animals belonging to plantation owners in southern
Geor-gia. In these tests the ears of naturally infested range
a2''.>i- were created with various chemic:.Is, and the animals were
the:. examined at regu?.ar interval- for the presence of ticks or the
treated ears.

This type of field test was fourn.-i to be un'?tisfactory for
determining the value of different ch',miuc.-ls as tick r'... ilents.
The comparatively short working period (2 to 3 months of maximum
tick abundance during the year), the irme'.er amount of clear-cut
data obtained from extensive experiments, the dependence on the
variable abundance of ticks in nature, and :rary other factors made
it advisable to search for a more satisfactory method.

The method finally adopted employs an adjustable hea:igear
and two cylindrical cages held tightly in place, one over each *'-ar.
The apparatus in its position on the head of an animal is outlined
in figure 1.

Each cylindrical cage is 5A inches long and 2- inches in
diameter. The supporting structure of the cylinder is a frare,.,ork
of leather, the outline of which is shown in figure 2. The greater
part of the wall is 16-mesh screen which is attached to the inside

*The author thanks E. E. Rogers, H. T. Vanderford, and Elihu
B. Blakeslee for their assistance and suggestions in assLrbliv.,
large number of the pieces of apparatus described herein for lie in
a preliminary test. Further thanks are extended to Mr. Blakeslee
for assistance in conducting the test.


ET-152




-2-


surface of the leather. The screen is strengthened and further
supported inside by two circular metal rods soldered to the screen
as a terminal circular brace (fig. 1, c.b.) and a subterminal
brace. (s.b.) The vial holder (v.h.) is attached to the leather
frame and hangs from the under side of the cylinder when the
apparatus is in position. This vial holder can be made of any kind
of strong cloth or flexible but strong leather. A soft cushion
of cylindrical weather strip is sewed to the inner edge of the
leather frame (fig. 1, c). This cushion reduces friction between
the cage and skin and prevents injury to the sk-in.

Each cylinder can be opened cr closed readily by the talon
fastener (fig. 1, t.f.) which is attached to the leather frame in
the front of the cylinder.

The leather frame also supports the halter, the buckles and
straps of which are attached to it (fig. 1). The halter is adjust-
able within limits, depending on the total length of the straps or
turnbuckles. The total lengths of the straps, including the amount
necessary for the attachment, varies with the position of the strap.
On the apparatus under discussion the length of the bead strap
(fig. 1, h.s.) is 8 inches; the nose strap (n.s.), 12L; the muzzle
strap (mu.s.), 142; the maxillary strap (m.s.), 9; and the neck
strap (ne.s.), 9 inches.

A large number of these cages can be assembled rapidly by
first preparing in quantity all the necessary parts to be used.
The list will include leather forms cut to the pattern shown in
figure 2, rectangles and circles of 16-mesh screen wire, rectangles
of cloth, various lengths of strap leather, turnbuckles, metal
rods shaped to circles and open circles, strap buckles, talon
fasteners, cylindrical weather strip, and brass split rivets.

The assembling procedure is, briefly, as follows:

(1) Pleat a strip of cloth (8" x 1") and attach it to one
of the shorter edges of a rectangle of heavy duck cloth (5" x 4-");
sew this cloth to form a cylinder into which a shell vial (100 mm.
x 25 mm.) will fit snugly.

(2) Attach pleated flare of this vial-holder cloth to vial-
holder tab of leather frame (fig. 2, v.h.t.) by sewing it or by
using brass split rivets, or by both.

(3) Sew cylindrical weather strip to inner edge (fig. 2,
i.e.) of leather frame.

(4) Attach a rectangle of 16-mesh wire screen (6" long by
43" wide) to the leather frame, by means of brass split rivets, so
that the long edge of the screen coincides with the long edge of
the leather frame. This screen will need to have a hole of the
same size as that in the vial-holder tab, and the two holes must
register when assembled.




-3-


(5) Attach the I?1on fastener to those edges of the leather
frame that will form 'he anterior midline of the completed e
(fig. 2, am.) -isin, casein glue as a temporary, and paper s"'.ples
as a permanent, fasteninig,.

(6) Shape the metal rods into closed and opn circular
braces. 3,ider these in place to .hc inside of the screen porti.i.
of the cage.

(7) Solder disk of 16-mesl!- wire screen to the circular
brace to form the outside end of the cage.

(8) Attach the necessary straps, buckles, and turnbuckles
,to form the halter shown in figure 1.

Technique of an Experiment with the Apparatus

The chemical mixtures to be tested were applied to the ears
of sheep. One week after treatment a set of ear cages was placed
on each animal so that each cage covered one ear and both cages
were held tightly to the head.

The animals were allowed to become accustomed to the cages
for 2 days before vials containing male and female ticks were
opened and quickly inserted into the vial holder. The vial holder
was then tightly closed behind the vial to prevent the escape of
the ticks.

Three times a week thereafter the ear cages and vial holders
were opened and the ears and vials inspected. Records were kept
of the number of ticks dead, the number attached, the number
engorging, the progress of engorgement, and the number fully
engorged. Engorged and dead ticks were removed at each examination.

Discussion

This experiment showed clearly the advantages of the new
method over previous methods. The fate of the ticks on both the
treated and control animals could be recorded readily in .-.oct
figures of the number dead, date of death, ri.,ber engorged, rate of
engorgemc:it, etc. In this one experiment such information .'.'as
recorded for S9.5 percent of the 412 tick-s placed in the vial
holders.

With this apparatus and a supply of adult ticks, experiments
with repf-llents may be conducted fcr at least 8 months of the year
as compared to 3 or 4 months with th previous method,




-4-


The cages were found to be sturdy, withstanding rubbing
and buffetting by the host animals well. Out of 20 cages 5 were
slightly damaged, but none seriously enough to affect the results
of the experiment.

The cages and the halters did not injure the host animals in
any way. Some of the wool was rubbed off at points of contact, but
the slight friction did not result in any open wounds. During the
first day or two after the apparatus was attached many of the sheep
attempted to remove the cages, but as long as the straps and turn-
buckles were tight and in place, none were dislodged. After the
second day nearly all the sheep wore the cages with no further
display of discomfort.
0
EXPLANATION OF FIGURES

Fig. 1. Sketch of ear cages and halter in
position on a sheep.

b. buckle
c. cushion
c.b. circular brace
c.t. cheek turnbuckle
h.s. head strap
l.f. leather frame
m.s. maxillary strap
mu.s. muzzle strap
ne.s. neck strap
n.s. nose strap
s.b. open circular brace
t.f. talon fastener
v.h. vial holder
v.h.t. vial holder tab

Fig. 2. Pattern for leather frame of
left ear cage

a.m. anterior midline, edges to
which talon fastener is
attached

o. opening in leather tab for
entrance and exit of ticks
between vial and ear cage


v.h.t. vial holder tab





I-n.s.


s.b.


--If.
-+. f.


mu.s.-


\
\ \


FIGURE I.


c.b.


-v.h.


v.h.t. --


0.--


FIGURE 2


0- 0 //


m.s.1




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