The Cockroach Connection—Ancient, Seemingly Indestructible Pest

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Current Comments” EUGENE GARFIELD INSTITUTE FOR SCIENTIFIC lNFORMATION!B I 3501 MARKET ST PHILAOELFI+A, PA 19104 The Cockroach Connection—Ancient, Seemingly Indestructible Pest. Part 1, Morphology, Behavior, and the I Relationship to Allergies and Disease Number 45 November 5, 1990 This two-part essay provides a brief overview of the cc&roach literature. Pan 1 looks at the insect’s capabdities, distribution, morphology, evolutional link with humans, and the connection between roaches and allergies and disease.

Anyone growing up in a city, especially in Cockroaches do surface from time to time tenements, has encountered cockroaches. in the popular consciousness. Two exam- From childhood I remember my mother ples that come to mind: the folk song that clobbering them with a shoe or a newspaper. became popular during the Mexican revolu- Looking back, I marvel at how mothers in tion (19 10-1940) that we all fondly know as slums managed to keep apartments free of “La Cucaracha,” and the famous scene from them. Even in modem high rises, these in- the film Pupil/on where a starving Steve seets are indefatigable--often outwitting McQueen captures a cockroach in his jail regulas extermination squads. However, cell and eats it on camera! However, for what I encountered as a child was nothing many years, cockroaches escaped such compared to my Army experiences. When prominence in the popular media—but that my outfit transferred from Colorado to all changed in the mid- 1980s. Texas, we were installed in barracks so full of cmkroaches, gas bombs had to be used to clean them out! I vividly recall a pile of Invasion of the Flying Roaches dead roaches that was literally two feet high. Like many other insects inhabiting the 1[began in late spring 1986. Anew immi- urban environment (like flies and silver- grant arrived in central Florida by boat. fish), cockroaches generally conjure up neg- This may not appear to be unusual, but this ative images in the US. 1 But unlike other was a newcomer with a difference-a one- insects, cockroaches seem to be associated inch fellow known to entomologists as with taboo topics. You don’t talk about Blatfella asahinai, or more commonly, the them in polite company. But this has never Asian cockroach. deterred us in selecting topics for essays in Previously, this insect had been virtually Current Contents @ I was curious to learn unknown in the New World. Indeed, the more about these ancient, well-adapted Asian roach had been described formafly by creatures. insect researchers only four years before its We’ve pulled together an interesting re- appearance in the US. This cockroach’s nat- view that demonstrates once again that even ural range is from southern India through the most practical and elemental of human Southeast Asia. Its introduction into central problems is closely intertwined with basic Florida was seemingly inauspicious---in research in entomology. Several years ago, June 1986 the species was limited to spo- in 1984, we reviewed entomology joumals,z radic infestations within 60 square miles of and that same year I published a tribute to Lakekmd-and was barely noticed.q my good friend Miriam Rothschild.3 Her But a year later, this changed. A major specialty is the flea, but it is not a big jump pandemic infestation was faced by Florida to talk about cockroaches. offtcials, By day, nothing seemed out of the

407 ordinary; but at dusk, things became quite crease your knowledge abut this fascinat- different. The Asian roaches came out of ing insect. hiding, and with a vengeance. In 1987 their density was estimated at up to 100,000 per acre+-or slightly more than two per square An Adaptable, Successful Living Fossil foot—and they infested nearly 500 square miles in three central Florida counties. Cockroaches are among the most primi- Telephone calls from distressed residents tive living winged insects-they have re- began to pour into public offices. The twi- mained essentially unchanged for more than light behavior of the insects was like a 300 million years. Cockroach fossils found cheap horror movie come frighteningly in coal and amber deposits show virtually alive. The roaches reprtedly flew in clouds no morphological differences in size or like locusts. Unlike other cockroach spe- shape from those inhabiting our cupboards cies, they were attracted to illumination— today. The oldest known cockroach fossil is street lights, trat%c Iights, porch lights, tele- Paleoblatta douvillei, found in Carbonifer- vision screens, and lights in houses. Even ous deposits of the Devonian period. Its more disturbing, the insects landed on peo- preferred habitat was among ferns in low, ple without hesitation. As the roaches en- moist areas along banks of rivers and tered homes, they were attracted to well-lit marshes.a rooms andlanded onthe brightest walls. As But today, roaches can be found just about interior lighting changed in rooms, the anywhere. Whh more than 3,500 identified roaches moved accordingly. During the cockroach species (ranging in size from 8 day, they acted just like their roach millimeters [3/1O of an inch] to nearly 70 brethren-scurrying into cracks and crev- [3 inches]), these insects are distributed ices in the walls and flows, often “hanging fairly generally throughout most continents, out” in kitchens, bathrooms, and potted with perhaps the most species residing in plants until dusks tropical America and western Africa. Of the In just three years, the Asian roach ex- total number of species, only 50 are re- panded itsterntory from 3 Florida counties garded as “pests’’—that is, an insect viewed to 18. Theentomology expexls’fears of the as detrimental or annoying to human beings. roaches hitchhiking in cars, trucks, and As a general rule, cockroaches have been trains to other parts of the country were found to survive comfortably at tempera- soon realized-an outbreak of the Asian tures between 19 and 1I6 degrees Fahren- roach appeared in Michigan in 1988, the heit, making the insects adaptable to most insects arriving by way of a travel trailer.G areas that humans inhabit.g (p. 10) The story at this point became a national The three widest spread species are the media event. American cockroach (Per-iplaneta Ameri- Unlike other insects (such as “killer bees” cana); the German cockroach (B. ,qer- or ticks carrying Lyme disease7), cock- manica), the most common insect pest roaches have not been proven to be life worldwide; and the Oriental cockroach threatening. Yet roaches seem to be espe- (Blafta orientalis), also known as the “water cially—perhaps irrationally-reviled. Last bug,” considered one of the filthiest of year US consumers spent $1.5 billion on household pests. IIJ commercial insecticides to rid their homes Cockroaches are very adaptable and virtu- of cockroaches-almost twice as much as ally indestructible. Some species can swim the Federal government spent on AIDS re- rapidly underwater for up to 2 minutes and search (about $790 million).g remain submerged for as long as 15 min- In this two-part essay, we’ll briefly review utes; the Asian roach has been collected in the cockroach literature, as well as focus on mountainous regions and even in areas of research specialties on this insect. Although intermittent snow.’t Roaches inhabit TVs, we may not be able to explain the irrational microwave ovens, and even submarines. 11 behavior of many humans in response to They have been found in hospital laundry these lowly creatures, hopefully we may in- baskets, incubators for premature babies,

408 and beauty salons in department stores.g Cockroaches have a well-defined court- (p. 11) Some 20 species have been found ship prior to actual mating. The mating rit- on aircraft. These were recovered from air- ual itself can take up to an hour. Male planes at airports in the US, Kenya, and roaches are attracted to virgin females in a New Zealand, suggesting that this may be a receptive condition. Such females fre- significant method of species migration. quently secrete pheromones, chemical sub- German and American roaches are the most stances that influence the behavior of other “frequent flyers.”g (p. 12) individuals of the same species. In Ameri- Speaking of transportation, some of the can roaches, on detection of the odor, the earliest records of cockroaches as pests can male initiates searching movements, first be found in ship logs. These insects are with antennae, then with wings fluttering, found in the reports of Sir Francis Drake actively searching the female out. (Scien- (sixteenth century) and William Bligh (eigh- tists have been vigorously pursuing the arti- teenth century). Drake reported one cap- ficial creation of the cockroach pheromone, tured Spanish ship to be overrun with cock- but more about this later.) roaches. Bligh recorded in the Bounty’s logs During the courtship ritual, the male a description of a successful method of kill- backs up into the female, depositing a sperm ing the cc&roach population–-using boil- packet that the female retains for four to five ing water. Centuries later, the insects are months while continually producing egg still a nuisance to shlppirtg-the German sacks, each holding 16 to 35 tiny roaches. roach appears to & the most successful spe- When the eggs are ready to hatch, the fe- cies, especially associated with galleys, cab- male deposits the ootheca. Soft white ins, and mess rooms.q (p. 12) nymphs emerge, hardening and turning brown in color on ex~sure to the air. Be- Cockroach Morphology and Behavior: fore becoming mature adults, the nymphs Like Roach, Like Human? go through several immature stages with molts in-between before a sexually mature For every cockroach one sees in the aver- adult is produced. German cockroaches ma- age home in the eastern US, there are-on ture in about 6 to 10 weeks and begin mat- average—1 ,00U not seem. Five fertile Ger- ing within just four to seven days of molting man roach females could theoretically pro- to the adult stage, starting the next genera- duce 45 million descendants in one year, but tion. I5 usually a pair of roaches produces 100,000 The cockroach diet is varied-ranging offspring annually. I1-13 from pet food to shoe polish. Cockroaches Until recently, cockroaches were classi- have a gourmand’s taste for the exotic, eat- fied as members of the insect order Orthop- ing wire insulation, cardboard, Styrofoam, tera, which includes praying mantises, katy- soap, paint chips, leaf litter, textiles, leather, dids, walking sticks, grasshoppers, and human hair .... (I think you get the picture.) crickets. However, in 1989 entomologists Entomologists have found that 12 roaches moved the insects to an exclusive order just can live on the glue of a postage stamp for a for roaches-Blattodea. 14 According to the week, while the American cockroach can Encyclopedia Britannica, survive on just water for a month, and noth- The cockroach is citatacterized by a flat- ing at all for three weeks. The German tened, oval body; iong, threadlike anten- cockroach can fast for two weeks. 1z nae; and a shining, biack or brown, leath- Cannibalism has been observed frequently ery integument. The head is bent in cockroach behavior, with recently molted downward, and the mouthparts point nymphs and copulating or injured adults es- backward instead of forward or down- pecially susceptible to predation. Over- ward as is the case in most other insects, crowding, food shortages, and high temper- The male usuatly has two pairs of wingx the femate, often wingless or with vesti- atures are factors that increase cannibalism. gial wings, carries eggs in egg cases Although roaches like to eat almost every- (called ootheca) that prcmude from her thing, there are some animals that like to eat body,10 these insects in return (thank goodness !)--

409 however, most live in tropical climates. tively generalized structure. Ever since the They include arachnids (such as theraphosid first monograph on the Oriental cockroach spiders and scorpions), ants, pwasitic was published in 1886, research on various wasps, amphibians (such as Bufb rnarinus, aspects of cockroach biology has contin- the giant toad of the West Indies, the Pacific ued.g (p, v) Today, the emphasis of biologi- islands, and Central America), lizards, birds cal research on these insects is with a view (a Peruvian bird named Trog/odyfes audax toward possible uses in extermination. is called locally the cuczzrachero), and Looking at papers in the 1988-1989 mammals (such as marsupials, monkeys, ISI@ databases with the word “cockroach” and rats).y (p. 364-6) in their titles, we found that 170 are devoted to the biology of the insect, 48 to methods of extermination, 16 to allergenic effects of Human Link roaches on humans, and 6 to cockroaches as possible vectors of disease. In Part 2 of Despite our abhorrence of cockroaches, this essay, we will take a look at these top- these insects and we humans are related—if ics. somewhat distantly. Neuropeptide hormones [bat control the way humans digest food may have a strong evolutionary link to Cockroaches: The Allergy and a recently discovered natural hormone af- Disease Connection fecting the cockroach’s own digestive system. A neuropeptide delivers messages Compared to the locust (which prod- from the nervous system to other parts of igiously destroys crops) or the mosquito the body and, in this case, stimulates muscle Atmpheles quadrimuctdatus (which trans- contraction of the digestive tract and blood mits malaria to humans), cockroaches have circulation.lb not been considered injurious insects to Ronald J. Nachman and William F. man. However, a growing body of evidence Haddon, US Department of Agriculture, Al- may change this view. For example, a 1988 bany, California, and colleagues discovered courtroom decision (during a “wrongful the hormone Ieucosulfakinin (LSK) while death” lawsuit) ruled that an asthmatic died analyzing tbe mashed heads of 3,000 from a fatal asthma attack initiated by w- roaches of the species f,eucophaeu ma- thropod allergy, and not from pesticides derae. They publisbed a paper entitled used in the home as was claimed by the “Leucosulfakinin, a sulfated insect neu- spouse. IX Furthermore, cockroaches are ropeptide with homology to gastrin and associated with four strains of poliomyelitis cholecystokinin, ” which reported that the virus, 40 species of pathogenic bacteria, and LSK in cockroaches is strikingly similar to 12 belmintb species with primary vertebrate the human neuropeptides gastrin II and hosts. But in no case has it been proved that cholecystokinin. 17 cockroaches have transmitted infectious dis- LSK has the highest biochemical correla- eases to man.g (p. 15) Indeed, in the middle tion yet reported between a neuropeptide in of the nineteenth century, a powder made a vertebrate and that in an insect---55 per- from dried cockroaches was recommended cent of the amino acid residues of LSK are as a diuretic! 19 Research continues on the identical with those of human gastrin. This cockroach/disease-vector link, however. finding led scientists to speculate that both In a recent review on health implications roaches and humans had the same ancestor of cockroach infestations, Richard J. Bren- about 500 million years ago. It also is an ner, Philip G, Koehler, and Richard S. indicator that species evolution occurs at the Patterson, University of Florida, Gaines- molecular level m well. id ville, point out that there are numerous ref- Cockroaches long have been the favorite erences to the isolation of pathogens from experimental animals for biologists and en- cockroaches in proximity to epidemics. tomologists because of their large size, ease These included an outbreak of dysentery in of culture, prodigious fecundity, and rela- Northern Ireland, tbe isolation of Salrno-

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nella bacteria from cockroaches captured in tests (compared with 84 percent for house- a hospital ward where gastroenteritis was dust mites). 18 There have been a handful of common, and a study in New York City studies over the years published on cock- where 89 percent of the cockroaches sam- roach sensitization in hospitalized patients pled (from a variety of human habitations, and laboratory workers. z7-so Earlier this inchrding restaurants, apartments, and hos- year, at the 46th annual meeting of the pitals) harbored at least three species of American Academy of Allergy and hnmu- pathogenic bacteria,zo Other recent publica- nology, there were further presentations on tions on this subject have linked American the allergenic relationship of cockroaches to roaches with bacterial diarrhea in Accra, humans. These indicate activity in skin re- Ghana,z I and have examined the distribu- activity tests to cockroach allergens and ex- tion and associated bacteria carried by the aminations of cockroach dust extracts for cockroach species Supella supellectilium in assays. a hospital in Rennes, France.22 Although at present there is no definite connection between cockroaches and dis- The Most-Hated Pest ease epidemics, there is a serious link between cockroaches and aflergies. In a previ- The major objections to cockroaches are ous series of essays, I discussed the psychological ones. Roaches generally behavioral manifestations, epidemiology arouse more hostility in us than bedbugs or and etiology, and diagnosis and treatment of fleas. A cockroach in one’s home is usually allergies.zJ equated with poor hygiene, and roaches do On the topic of cockroach-related aller- spoil food by depositing saliva and feces on gies, the items that humans are hypersensi- it and leave unpleasant odors (derived from tive to include bdly remains, cast skin, the abdominal glands). feces, and ootheca egg cases. The actuaf Our negative reaction to these insects may allergen-causing agents in cockroach mate- be comected with characteristics that help rials are proteins. Unfortunately, some cock- the insects avoid capture. These include roach proteins persist in their allergenic ca- great running speed (up to three miles per pability for many years. Indeed, some are hour) and the ability to squeeze their bodies virtually indestructible---even boiling them into inaccessible cracks due to the softness for hours doesn’t destroy the proteins’ al- and flexibility of their exoskeleton.g (p. 16) Iergenicity. Of the more than 50 identifiable Unlike other household pests, such as cockroach proteins, only 10 to 15 actually ants, cockroaches are not seasonal pests. cause allergic reactions.2A Rather, cockroaches are perennial and, The most common symptoms of cock- when discovered, come not singly or even roach allergies are sneezing, fits of asthma, in scores, but in the tens of thousands. and inflammation of the skin (including Many species, unlike their Asian brethren, itching eruptions on the hands), which avoid brightly lit areas (called photophobia) caused the coining of the phrase “cockroach and run when exposed. These insects ap- dermatitis.”2s Cockroaches were not impli- pear in places that cause much consternation cated in allergic conditions until generalized and dismay, such as bread boxes, cup- skin rashes on pmple (following exposure boards, bathrooms, dishwashers, clocks, to the insects) were first refxxted in 1943.’26 televisions, bed linens, and so on. But keep Statistics indicate that about 7 to 8 percent in mind that while we may cringe at the of Americans have an allergy to roaches. thought of roaches cavorting in our kitch- Among those who have grown up in roach- ens, not all of us think similarly; these an- infested homes, the allergy rate can be as cient creatures and their eggs are used as a high as 70 percent. 12 Indeed, allergy to high protein food source in Australia, Thai- cockroaches is the second most common land, China, Japan, and other parts of Asia.9 hypersensitivity among asthmatics (house- (p. 366) Indeed, for many years there has dust mites are ranked first) with a 51 percent been a restaurant in Los Angeles, California, positive reaction in standard skin scratch specializing in cockroach fare.

411 In Part 2 we will look at what science is related to cockroach investigations by scien- doing to control this pest-via pesticides, tists. ● **.. biochemical analogs of the insects’ own hormones and pheromones, and even “birth My thanks to CJ. Fiscus, Peter control pills.” We also will highlight some Pesat’ento, and Judith Schaeffer for their entomological Citation C/assics @ that are help in the preparation of this essay. o Iwll.sl

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