Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, November 1, 1994 TAG: 9411010111
SECTION: VIRGINIA PAGE: B-3 EDITION: METRO
SOURCE: DAVID REED ASSOCIATED PRESS
DATELINE: BLACKSBURG LENGTH: Medium
A Virginia Tech research scientist and avid admirer of the cockroach thinks her killer bait fits the bill, and so do her industry sponsors.
Heather Wren, an insect physiologist, said the compound she developed wipes out cockroach populations and prevents reinfestation.
A key ingredient is a nutrient they not only require but seem to love - the roach version of a juicy steak.
Males die after they breed, the females' bodies sabotage themselves before their eggs develop and adolescents are slowly crushed to death within their shells.
Ghastly tactics, indeed. But these are tough creatures we're dealing with.
The cockroach has learned a few tricks in its 350 million years on the planet, and some are resistant to most pesticides.
Periplaneta. An insect so fit from the start that it has survived virtually unchanged since Earth had a single continent, long before the dinosaur.
``The cockroach will never be killed off - you can only control them where you don't want them,'' Wren said.
They eat just about anything, and they don't eat much. ``A crumb you can barely see is quite a meal for a cockroach,'' she said.
The species that colonize in homes can go three weeks without food. If you starve them, they molt to a smaller size. They eat and recycle the nitrogen in their waste so if their diet is unbalanced - say, all they have is some spilled sugar or flour - they remake digested food to form proteins.
``They are known to gnaw on people's feet while they are sleeping to eat the dead skin and drink the saliva on mouths,'' Wren said. But that's mostly in the tropics where people sleep on the floor without covers.
Cockroaches are rarely seen because they hate light and air movement and are thigmotactic. That means they like to squeeze into the tightest crevices possible so their backs and bellies touch surfaces, preferably somewhere in the basement.
As everyone learns after turning on the bathroom light, spotting the detestable bug and swatting it with a magazine - they can flatten themselves like paper, survive the first blow and then skitter into some crack.
And, boy, can they breed. At the ``cockroach stockroom'' in the Virginia Tech insect laboratory, Wren said she starts with a colony of 42 cockroaches and two months later there are 400 to 500 of them crawling around an otherwise empty aquarium.
In a survey by a colleague, residents in a Roanoke apartment complex were asked how many roaches they could tolerate. ``The answer was less than one, that just one is offensive,'' she said.
They spread germs that can cause disease by, for example, crawling up a drainpipe to get a drink and then walking across a kitchen counter, where the germs are collected on the morning toast as it's put down to be buttered.
``What is happening now with regular spraying schedules, at restaurants, for example, is that a few resistant cockroaches survive and reproduce,'' Wren said. ``The offspring inherit resistance to a particular insecticide, breed and thus increase the number that are resistant, until the entire colony is invulnerable to the insecticide.''
In March 1992, the Pesticide Control Board gave her $53,000 for a two-year study of alternatives to toxic pesticides. When the project began to show promise, Virginia's Center for Innovative Technology chipped in $24,000 and Dominion BioSciences Inc. at Virginia Tech's Corporate Research Center licensed the technology.
The discovery is a breakthrough in an insect-killing method called insect growth regulators. Previous growth regulators were based on killing nymph cockroaches at the molt stage.
Wren said hers is based on the insect's metabolism and is the only compound that kills adults and stops resistant strains by preventing breeding.
A U.S. patent is pending and testing by the Environmental Protection Agency will begin in 1995. A commercial product is expected by 1997.
``This new technology addresses common insect pest problems that everyone wants to eradicate without the fear of harming the environment,'' said Steve Banegas, president of Dominion BioSciences.
by CNB