Health Inspection Service (APHIS) entomologists con- 

 ducted a survey for 0. puertoricensis in the Dominican 

 Republic. Surveying for this burrov^^-dwelling tick was 

 greatly enhanced due to the use of a vacuum sampling 

 device developed by researchers of the University of 

 Florida at Gainsville. Serological evaluation, using an 

 agar gel double-diffusion test to determine host blood 

 present in the ticks, v\/as performed at the Pathobiology 

 Laboratory of the National Veterinary Services Labora- 

 tories, (NVSL), Ames, lov^^a. No ticks were shown to 

 have fed upon hogs, although 20 percent of those col- 

 lected had fed on rats and mongooses. ASF virus has 

 not been isolated from samples taken in the Dominican 

 Republic in 1983. The eradication effort to curb this 

 highly contagious viral disease appears to be progress- 

 ing satisfactorily. 



Status of ARS Cattle Fever Tick Research 



In October 1983 the new USDA, ARS Cattle Fever Tick 

 Research Laboratory was opened at Moore Field near 

 Mission, Texas. The quarantined facility is situated 

 within double security fences and occupies about 103 

 acres of land. The new laboratory will provide oppor- 

 tunities for field-type experiments that were not possi- 

 ble at the old laboratory site at Falcon Heights, Texas. 

 The laboratory complex includes a general laboratory 

 and office building, a separate acaricide laboratory 

 building, barns with stalls to accommodate up to 64 an- 

 imals, a covered experimentai dipping vat and spray 

 application area, a program dipping vat, and a utility 

 building. Future research efforts at Mission will include 

 studies to evaluate the susceptibility to acaricides of 

 fever ticks collected from tick outbreaks within the Tick 

 Eradication Quarantine Area, which separates Texas 

 from Mexico. Other areas of research shall include the 

 following: 



(1) acaricide testing as warranted by special problems 

 or the need to test selected new chemicals, 



(2) studying the role of white-tailed deer and exotic 

 game in the ecology of fever ticks, 



(3) expanded efforts to perfect the sterile hybrid Boo- 

 philus method of tick eradication, and 



(4) a variety of other projects related to the ecology 

 and eradication of Boophilus ticks. Dr. Ronald B. Davey 

 is the scientist-in-charge of the laboratory. 



During 1983 Dr. Glen I. Garris and his staff of the ARS 

 Tropical Tick Research Laboratory at Mayaguez, Puerto 

 Rico, completed field evaluations of fenvalerate, per- 

 methrin, and amitraz. None of these three acaricides is 



as effective against adult B. microplus as organophos- 

 phates such as coumaphos or crotoxyphos, but they 

 are very efficacious against immature ticks. Spray 

 treatments at the manufacturer's recommended con- 

 centrations provide almost 100 percent protection for 

 4-7 days' posttreatment against reinfestation of treated 

 cattle by larvae. Tick research in Puerto Rico also in- 

 cludes the second year of a 2-year study of S. mi- 

 croplus ecology. When this investigation is completed 

 in December 1984, it will confirm the survival times of 

 larvae in both high and lovv rainfall areas on the island. 



Dr. Garris has begun a cooperative study of Amblyom- 

 ma variegatum \N'\i[) French scientists on Guadeloupe. 

 They will evaluate the susceptibility of A. variegatum to 

 acaricides and determine factors that influence its dis- 

 tribution in the Caribbean. Studies will also be conduct- 

 ed to determine the survival rate of free-living stages of 

 the tropical bont tick. 



Experimental Transmission of Anaplasmosis by Males 

 of Dermacentor albipictus and D. occidentalis 



Agriculture Research Service scientists recently une- 

 quivocally incriminated the males of Dermacentor al- 

 bipictus and D. occidentalis as intrastadial, biological 

 vectors of Anaplasma marginale under experimental 

 conditions."^ This is apparently the first such record for 

 the males of a one-host tick species such as D. albip- 

 ictus. An earlier preliminary study by Stiller had sug- 

 gested that the males of the one-host tick, D. albip' 

 ictus, could serve as competent intrastadial, biological 

 vectors of the causative agent of anaplasmosis. 



The confirmation of the role of one-host males to act as 

 intrastadial, biological vectors of A. marginale has po- 

 tential significance because if such males transfer to 

 more than one host animal in the field, they could ac- 

 quire and transmit the parasite in the absence of infec- 

 tion in the host animal on which they fed as immatures. 

 This could increase the vector potential of one-host 

 ticks, perhaps including important vector species such 

 a Boophilus micro-plus and S. annulatus. 



The males of the three-host species, D. occidentalis, 

 are especially efficient vectors of A. marginale as 

 demonstrated in the experiment where as few as three 

 D. occidentalis males transmitted the causative agent. 

 This may be especially important in that it has been 

 often assumed that A. marginale is transovarially 



"Stiller, D.; Johnson, L. W.; and Kuttler, K. L. 1983. Experi- 

 mental Transmission of Anaplasma marginale TheWer by Males 

 of Dermacentor albipictus (Packard) and Dermacentor occiden- 

 talis Marx (Acari: Ixodidae). Proc. US Animal Health Assoc, pp. 

 59-65. 



