One of the world's most important collections of ticks, currently in residence in the Washington area, may be mothballed because funds for the coming year are unavailable.

Officials report that lack of $140,000 threatens to force the world's only comprehensive collection of ticks -- pests that are responsible, worldwide, for human suffering and economic loss -- to close.

At the end of the next fiscal year, on Sept. 30, 1988, two scientists and a clerk comprising the acarology unit of the National Institute of Allergy and Infectious Diseases will be given their walking papers and the unit's collection of 120,000 tick specimens from all over the world will be shut down.

The National Institutes of Health -- a $6.2-billion-a-year operation with more than 13,000 employes -- simply cannot find three job slots and $140,000 to maintain the tick collection.

The reason, say NIH sources, is that the Reagan administration's crash program to deal with acquired immune deficiency syndrome (AIDS) is taking all available funds. In a letter to Sen. Lowell Weicker (R-Conn.) NIH deputy director Joseph E. Rall said: "While we agree . . . that research on the classification of ticks is . . . important . . ., the No. 1 . . . priority identified by the Department of Health and Human Services is AIDS."

Rall went on to say that space, money and personnel have been shifted to AIDS research and that "we can no longer afford to support the acarology unit."

James E. Kierans, an expert in acarology, the study of the zoological order that includes ticks and mites, is confused by the decision. So is Dr. Robert Traub, an emeritus professor at the University of Maryland School of Medicine who has mounted a campaign to keep the tick collection open. Traub's argument is simple: New disease-carrying ticks, and the germs and viruses they carry, keep turning up all the time in various parts of the world. As Kierans said: "Ticks are parasitic on all types of vertebrates except fishes."

So if a strange-looking tick is found (as was the case early this year on lesser pandas acquired by the National Zoo) and there's no place to go for identification, it may be more difficult to judge the danger to human beings or livestock.

Russell C. Johnson, a University of Minnesota microbiologist and authority on tick-borne diseases, agrees that the threatened collection is an important resource. And Alan B. MacDonald, a Southampton, N.Y., pathologist who has made key discoveries about the syphilis-like nature of tick-borne Lyme disease, called the proposed mothballing of NIH's tick archive "an outrage".

Johnson and MacDonald independently stressed the need, in research on tick-borne diseases, for understanding of the complex interaction among pathogen (germ or virus), vector (tick) and host (humans or other vertebrate animals). Because ticks are parasitic, the identity of their host is often as important as the identity of the tick itself, Johnson explained.

New tick-borne diseases (and sometimes old diseases in new guises) are coming along all the time, MacDonald said. He cited ehrlichiosis, a disease thought to occur strictly in dogs, which is now believed to have migrated into the human population. A report of six human cases was published in the June 12 issue of the Journal of the American Medical Association.

The tick collection is something like a reference library, and like a library must be open-ended to be of continuing value. A library that never gets new books soon becomes obsolete, and people go elsewhere to keep up with current knowledge.

Of about four tick collections elsewhere in the world, none approaches the comprehensiveness of the NIH's small facility in a warehouse building at the Smithsonian Institution's museum support center in Suitland, Md. It contains examples of almost 90 percent of the 850 species of ticks known to exist worldwide. They are preserved, either in alcohol or by some other means, and each exhibit is documented as to place of origin and, where possible, identity of the creature from which it was taken.

The largest of the other collections is at the British Museum in London. Smaller, regional collections are maintained at Leningrad in the Soviet Union, Toulouse in France and Onderstepoort in South Africa.

Only three years have passed since NIH moved the tick collection from the Rocky Mountain Lab in Montana to the Smithsonian complex in Prince George's County at considerable trouble and expense. One year after this move, NIH first tipped its hand about mothballing the collection.

Traub, in a letter to Sen. Weicker, noted, "There are no scientific reasons to justify closing the acarology unit, and in view of the funds expended so recently on its transfer to the Washington area, it is hard to believe that sound financial reasons by themselves would dictate the decision to terminate its existence."

NIAID, Rall acknowledged, "does not wish to see the acarology unit closed." However, he added, "it has never been NIAID's intention to provide support indefinitely."

Conversations have been going on for several years between NIH and the Smithsonian about eventual takeover of the ticks by the institution, which harbors many such animal archives (including one of the world's largest collections of cockroaches). But recently the Smithsonian has been having money trouble, too.

Scholarly institutions, such as the Smithsonian, have standard procedures for shouldering research burdens. They want to know how much it will cost ($140,000 a year in this case) and then typically add 15 percent as a management fee for a total of about $160,000.

Then the institution goes out looking for support -- ideally, one-time-only endowment money to satisfy the bottom line. At 5 percent interest, an endowment of roughly $3.2 million would yield enough to keep the tick collection staffed and operating.Judith Randal and William Hines are free-lance writers in Washington.