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Roaches: Nuisance or Science?

By Shari Rudavsky

Louis M. Roth does not have to go looking all over the world for his specimens--they come to him, usually in an envelope. Roth, who is known in the field of entomology as the leading expert on cockroaches, frequently receives exotic insects in the mail with requests to identify them.

"In many cases I can recognize a species just by looking at the genitalia," says Roth, a research associate in the Museum of Comparative Zoology (MCZ). Roth says that he also looks at an organism's wings and the sexual glands of a male when attempting to place a specimen taxonomically.

The entomologist has been studying the behavior and taxonomy of numerous cockroach species for more than 40 years, the last six of which he has spent working on the fourth floor of the MCZ. Before coming to Harvard in 1982, Roth headed the Army's Entomology Research Group in Natick, where he pioneered many of the basic studies on the behavior of these insects, which have been in existance for more than 300 million years. One recent morning, Roth discussed his four decades with cockroaches, explaining his work and peppering his reminiscences with humorous anecdotes about his days with the army.

Lately, the mail has held quite a few specimens for Roth. Last year, the U.S. Department of Agriculture (USDA) sent him some cockroaches found in Florida, with a request for identification. He looked at the specimens and decided that they were German cockroaches, but the USDA wrote back, saying that the insect was not behaving like the German roach. Unlike this common species, these cockroaches are attracted to light and can fly.

Roth looked at the specimens again and decided that they might be Asian cockroaches, which had never before been seen in America. He sent the specimens to a Japanese entomologist who confirmed that it was indeed the species Roth suspected it to be. Roth and USDA officials speculate that this roach species was recently produced to America.

USDA officials say that Roth's work was instrumental in helping them decide how to approach the growing cockroach infestation problem in Florida. "[The Asian cockroach] has a present potential to be a pest problem, so [Roth's] work is very significant in defining the pest problem," says Richard Patterson, research leader at the USDA's division on insects affecting man and animals.

No Simple Task

Identifying a cockroach is no simple task. There are currently about 4000 described cockroach species, and Roth says he thinks there are "at least twice as many undescribed species." A biologist must determine that the organism has not previously been assigned to a species before he or she can say it is a new species. To ensure this, the entomologist must turn to detailed descriptions of the species prepared by his colleagues.

And for many insect researchers, Roth is often that colleague. Currently he is working on describing a species found on the Island of Krakatau, where the environment was destroyed by a volcanic eruption about 100 years ago. He suspects that the species now inhabiting the island emigrated from one of the neighboring islands, such as Java or Sumatra.

In fact, the Harvard entomologist has so many requests to identify species that he must turn some down. Recently, Roth had to decline an invitation to study some specimens found on an expedition conducted by the Russian Academy of Sciences--the same institution he wrote to several years ago asking for a specimen he was interested in studying. "We didn't have glasnost then, and I'm sure the minute they saw the U.S. Army letterhead...I never heard from the man," he says.

Roaches From Down Under

What has been occupying most of Roth's time these days is a much more extensive research project--the revision of an entire family of Australian cockroaches. The project is based out of the centerpiece of Roth's MCZ office, a cabinet about four-feet high with four compartments, each holding about 20 trays of pinned cockroach specimens. totaling about 6000 specimens.

"I doubt I'll ever finish it," he says of the study, which he began in 1982 at the behest of the Australian government. Roth currently examines pinned cockroaches, and if there is enough specimen, he prepares slides of the insect's glands to aid in classification of the various species.

"There are some species which are very, very similar and that have the same markings. If you just looked at these markings without studying the internal structures, you would assume they are all the same," he explains. "Some of them are striking. They may not look that way when you see them with the naked eye, but under the scope..." he adds.

Roth, who received his Ph.D. in insect physiology in 1946, is the specialist to whom biologists turn most frequently for information on cockroaches. "He's probably the foremost cockroach taxonomist. He has a world-renowned reputation. He's a very brilliant and helpful individual," Patterson says.

While Roth studies only pinned specimens now, in his earlier years with the army, he published some of the basic studies on cockroach behavior. Before chemical sex attractants were termed pheromones, Roth discovered the effect that these female secretions have on the males of their species. The author of 163 publications has also described the life history of several species previously unknown to entomologists.

"Everybody who works with cockroaches ends up reading him," says Mary H. Ross, professor of entomology at Virginia Polytechnic Institute and State University. "He's certainly the number one authority on the cockroach on any sort of basic information." Ross, who studies the genetics of German cockroaches, says that she frequently refers to Roth's work on the life history of the species she studies.

Roth downplays his own contributions to the field, talking instead about other specialists whom he says conducted the most significant studies but have since retired or died. "That's the way to become an expert, you outlive the others," jokes the 70-year-old Roth.

Although Roth has not worked with live specimens for about 10 years, he misses his behavioral studies. "A cockroach on a pin is nothing like the living thing. It doesn't smell the same: it's not waving its antennae at you," he says.

Army Days

Much of Roth's work with live specimens took place when he worked with the U.S. Army. As an army entomologist, Roth was in an odd position. When he first started working in the lab, the group was studying the biological detoriation of materials and soon expanded their scope to basic insect behavior. "When I first arrived there, the philosophy was, 'Don't worry about the application of the finding, someone else will do that,'" Roth recalls.

But throughout his army career, Roth faced skepticism from army officials who worried more about upholding the good name of the army than about publishing works of scientific significance. In the early 1950s, when Roth was ready to publish his findings on the reproductive behavior of the cockroach, the army refused to give him clearance. After he submitted the paper to Washington officials for review, he recalls, "It came back with a note saying that it was unacceptable because of the use of the word 'sex' in the title. I took the word 'sex' out of the title and got back a note saying that 'the title is fine, you can't publish this because of the contents.

The Washington officials worried that a paper on cockroach behavior published under the auspices of the army's lab would be bad publicity for the service. Roth decided, however, that the information should be made public, and told his lab chief that he still wanted to publish the findings. The chief told him that if he did so, he should leave out any mention of the army. Thus, the study was published with the author's home address, not that of the lab where they conducted the research, as is customary in scientific papers.

Although the general, who directed the lab, had been unimpressed with the findings on paper at first, his attitudes changed slightly a few months after the censorship controversy, when he took a tour of the laboratory. During the visit, Roth demonstrated the effect of the female sex attractant, or pheromone, on the male roach.

As the general watched, Roth waved a glass rod which had been dipped in the substance, and a wave of male cockroaches followed the wafting smell. The general then said that he wanted everyone else at the meeting to see the demonstration.

Ten years later, national attention turned to the cockroach as the federal Ribicoff Committee started investigating the use of pest controls which do not have a severe effect on the environment. The investigation was prompted by the publication of Rachel Carson's "Silent Spring," which decried the use of dangerous pesticides. A national news program televised some of the hearings, including a demonstration of the effect of the female sex attractant, without mentioning the army lab's part in the study.

"The following morning," Roth recalls, "my boss called me and said, 'Did you notice that they didn't give the army any credit in finding the behavior?'" So, Roth sent copies of salient sections of his paper to the Ribicoff Committee, omitting the title page without the army address.

Army officials later considered using the chemical substance as a lure for cockroaches. "They plugged it as a bigger and better mousetrap, but I knew it wouldn't work," Roth says. Because one male can inseminate a number of females, the proposed cockroach trap would probably have little effect on reducing an infestation, he explains.

In addition, research has shown that a large percentage of American cockroach eggs hatch even if they are not fertilized by a male. Referring to the army's proposal to use the sex attractant as a pesticide, Roth says, "I had a vision whereby eliminating males, you could create a super race of females."

About a decade later, during the Vietnam War, army officials again considered trying to synthesize the potent female sex attractant, but this time they wanted the substance to function as a sort of natural spy detector, Roth recalls. Army officials proposed spreading the substance in areas occupied by the North Vietnamese, so anyone who crossed the boundaries between North and South Vietnam, such as a South Vietnamese spy, would be given away by a tell-tale appeal to male roaches.

Bringing Home His Work

Roth remembers another incident regarding his controversial paper on cockroach reproductive behavior. A friend saw that the paper was published with the authors' addresses, not the lab's. "He wrote back: 'Dear Lou, What in hell is going on in your basement." Roth laughs and adds that he has attempted to bring his work home, with diastrous results.

Trying to determine the efficacy of a wasp that parasitizes roach eggs, Roth brought home 100 cockroach egg cases and hid them in his basement. He then released 450 wasps in the basement, allowing them to parasitize the eggs. When it came time to collect the egg cases, Roth made two unpromising discoveries: First, that the wasps parasitized less than a third of the egg cases, and second, that he could not find about 20 of the egg cases.

"I didn't say anything to my wife, and a couple of weeks later, I heard a scream from my wife. She was down in the basement pointing to some newborn little cockroaches." Roth shakes his head. "That was the last experiment I did at home."

Now that Roth works primarily with pinned specimens, he does not have to worry about the insects escaping. While he concedes that he does miss the behavioral studies, he adds that the studying cockroach taxonomy is very important, particularly because so few people are doing it. However, funding for taxonomic research is scarce, and the entire field stands in danger of becoming a science of the past, he says.

"Today [taxonomy] is given lip service really," Roth says. "It's not glamorous." Ironically, Roth adds, "People keep plugging biological diversity, but it's still difficult to get support."

In fact, Roth says one known species on the Steppes of Russia have gone extinct during his lifetime, and he suspects that other unknown cockroach species are now gone as well. "At the rate the tropical rain forest is being destroyed, many of my friends are probably becoming extinct. I think that is one of the reasons we should be describing these things, so we have a record of them."

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