Pesticides Kill Critters’ Urge for Reproduction

SAN FRANCISCO —  Birth control may succeed where an arsenal of toxic agents have failed: in checking the baby boom among fleas, cockroaches, mosquitoes and other insect tormentors of man and beast.

A new generation of pesticides recently put on the market endangers these pest populations without threatening public health or the environment, say experts on the project spawned by a developer of the birth control pill for women.

Studies and field tests point to “insect growth regulators” as the first weapon potentially powerful enough to wipe out such poison-resistant die-hards as fleas and roaches, which have accompanied humans from cave to condominium.

The regulators, or IGRs--synthesized versions of natural hormones in the brain--interrupt the insect’s life cycle, making it incapable of reproducing.

Developed at Zoecon Corp.-- zoe from the Greek for life and con for control --in Palo Alto, IGRs do not stop adult bugs dead in their tracks.

Rather, they go after pests during the immature stages. Eggs do not mature into larvae; larvae do not mature into adults.

Usually, as insect young develop into adults, they undergo a series of molts--from three to as many as 20 or more--during which the outer layer of the body wall is shed and renewed. IGRs disrupt these cycles by imitating insect growth hormones.

“While conventional pesticides poison pests, IGRs mimic their biochemistry to control their population--presenting virtually no hazard to people, pets or environment because they are species-specific,” said Bill Donahue, senior research biologist at Zoecon’s corporate headquarters in Dallas.

“IGRs are the future,” said Dallas veterinarian Jim Humphries, host of a syndicated talk show. “They are a breakthrough that is safer and more effective than any insecticide ever developed.”

In the consumer mass market, Americans spend an estimated $600 million annually on products to control fleas, ants and cockroaches. Each year, they buy another $250 million in flea, tick and fly poisons from veterinarians and pet stores. In addition, professional pest control operators pour $80 million yearly into the pesticide market.

Hoping to cash in on the public’s growing reluctance to use toxic agents, chemical companies have begun to actively pursue the development of IGRs, which first came to researchers’ attention in the 1930s.

IGR sprays, foggers and concentrates available to U.S. consumers through veterinarians, pet shops and exterminators can combat roaches, fleas, mosquitoes, horn and corn flies, pharaoh ants, beetles and some stored food insects such as weevils.

Experts at Zoecon, founded in 1968 by birth control pioneer Carl Djerassi, and other firms are testing the technology for such possible new uses as curbing insects that each year devour 10% of crops and stored grains.

“Our focus has turned toward agriculture,” said Jim Howze, Zoecon’s manager of marketing communications, noting that the horn fly alone causes about $70 million in damage annually by sucking blood from cattle and accounting for up to 20 pounds in lost body weight per head.

“The public’s anti-chemical attitude and changing regulatory climate that bans pesticides has made the time right for using this technology in areas once considered unprofitable ventures, such as termite control,” he said.