continued. Comparisons were made of the total number of 
adult female ticks recovered from deer and bovine hosts and 
of the associated ovipositional and reproductive parameters 
of these ticks. Significantly fewer ticks were recovered from 
deer (302) than from cattle (3,818). The difference was 
attributed to the more efficient grooming behavior of the 
deer. The mean weight of the female ticks collected from 
deer was significantly less than that of ticks from cattle 
(240.13 mg and 344.66 mg, respectively). About 15 percent 
of the engorged females recovered from the deer weighed 
less than 100 mg, and these ticks had probably been removed 
prematurely by grooming. A significant difference in the 
mean percent hatch of eggs from deer (65.22) and cattle 
(74.33) was observed. The index of reproduction (IR), a 
value that is based on the total number of engorged female 
ticks from a host, the mean weights of the egg masses from 
these females, and the mean percent hatch of the eggs was 
19.7 times greater when cattle rather than white-tailed deer 
were hosts. It was concluded that the deer are biologically 
suitable hosts, but they are considerably less efficient host 
for B. annulatus than cattle. 
The efficacy of a 20.2 percent emulsifiable concentrate 
formulation of the pyrethroid acaricide cyhalothrin was 
tested using two concentrations (0.007 percent and 0.01 
percent) as a whole body spray against B. microplus on 
cattle. Based upon IR calculations, the 0.007 percent Al 
treatment provided 92.4 percent control and the 0.01 
percent Al treatment provided 97.3 percent control. An 
evaluation of an “‘improved”’ cyhalothrin formulation has 
been scheduled. 
Boophilus Tick Program in Texas 
Tick eradication activities along the U.S.-Mexico border 
were successful in 1987. Thirty-four herds of Mexican 
livestock were apprehended by the Veterinary Services Tick 
Eradication Program employees along the Texas-Mexico 
border during this period. The herds totaled 26 cattle, of 
which 11 were infested with Boophilus ticks, and 22 horses 
which were free of cattle fever ticks. The total of 48 animals 
apprehended in 1987 compares to 74 Mexican animals 
apprehended in 1986. 
The temporary preventative quarantine area in Cameron 
County was converted to a control purpose quarantine area 
to monitor livestock in the high-risk area. As a result, one 
premise was found infested with Boophilus ticks. 
Three premises in the free area of Zapata County were 
found infested with cattle fever ticks in the vicinity of the 
previously infested Loma Llano Pasture. Range pasture 
conditions continued favorable due to adequate rainfall. 
Forage was abundant in most areas along the Texas-Mexico 
border. 
Research Accomplishments for 1987 by 
Animal Diseases Research Unit (ADRU), 
USDA, Agricultural Research Service, 
Pullman, Washington, and Moscow, Idaho 
Light and electron microscopes were used to obtain the first 
clear evidence that Anaplasma marginale infects tick 
salivary glands. Morphology of two strains of the parasite in 
salivary glands of three experimentally infected species of 
Dermacentor ticks suggests that the parasite replicates in 
this tissue before being introduced into cattle. If further 
studies confirm that the organism seen in the salivary 
glands represents the tick-transmitted stage of A. marginale, 
the antigenic profile of this stage can be characterized and 
unique antigens possibly included in a vaccine to protect 
cattle against tick-transmitted anaplasmosis. 
A cloned DNA probe from the gene coding for an A. 
marginale surface polypeptide was used to detect A. 
marginale infections in individual tick tissues from three 
Dermacentor species. The DNA probe can detect all strains 
of A. marginale thus far tested, but does not cross-hybridize 
with A. centrale or A. ovis. Anaplasma marginale infection of 
Dermacentor tick salivary glands was confirmed with the 
DNA probe, revealing that the parasite was present before it 
could be detected microscopically and before it was infective 
for cattle. 
Immunization of cattle with a purified A. marginale surface 
protein of 36,000 M.W. induced protection against both 
homologous and heterologous challenge. Cattle that did not 
develop infections were confirmed negative by DNA probe. 
Experiments with unifested cattle and cattle infested with 
marked male/female Dermacentor ticks held together in 
indoor/outdoor pens revealed that approximately 30 percent 
of ticks recovered from the animals had transferred to new 
hosts. Interhost transfer by adult ticks may be an important 
means by which ticks transmit A. marginale in nature. 
Anaplasma marginale-infected male Dermacentor andersoni 
held in packets off the host and in the field survived for 7 
months and transmitted the parasite to susceptible calves 
after 121 days. The ticks appear to act as reservoirs of A. 
marginale through the summer and fall, but chronically 
infected vertebrate hosts appear to be the only significant 
overwintering reservoir of A. marginale. 
Tick Identification and Vat Management Training 
Along United States-Mexico Border 
Tick identification and vat management training was con- 
ducted May 18 through June 6, 1987, for the personnel 
along the United States-Mexico border from Brownsville, 
Texas, to San Ysidro, California. The training included 52 
State and Federal animal health personnel actively engaged 
