Synthetics Mimic Natural Brain
To control pheromone production and other life functions, insect physiologist
Peter Teal applies artificial neuropeptide chemicals to a tobacco hornworm
Changing an insect's behavior by "messing with its brain" may be
the way to stop pests in the future. Agricultural Research Service scientists
have developed artificial brain chemicals designed to mimic natural chemical
messengers that control molting and other life functions.
"Commercial products containing artificial neuropeptides that can be
sprayed onto corn earworms, for example, could be developed in about 5
years," says Ronald J. Nachman. He is a chemist in the ARS Veterinary
Entomology Research Unit at College Station, Texas.
Nachman and ARS entomologist G. Mark Holman began studying
neuropeptides--chemical messengers sent out in insect brains to stimulate
life-sustaining functions--in 1987. These messengers are made up of strings of
amino acids, the building blocks of protein, and control an array of behaviors.
They can halt molting (shedding of outer covering), upset mating, alter
digestion, or disturb water balance.
By 1996, Nachman and Holman had built the first of eight analogs--artificial
versions that mimic natural brain chemicals.
The artificial versions don't work quite like the real thing.
The biggest problem in delivering the mimics was getting them to penetrate
the pest insects' tough skin, or cuticle. Nachman overcame this obstacle in the
laboratory by using a combination of boron, carbon, and other chemicals,
replacing one part of a string of amino acids with this combination. The
result: The molecule became greasy. The greasy quality of the molecule matched
the physical characteristic of the insects' cuticle, making absorption into the
Nachman sent his greasy analog to ARS insect physiologist Peter E. A. Teal
in Gainesville, Florida, for further testing.
To stimulate the production of sex pheromones, Teal applied the analog to
the skin of tobacco budworms and cotton bollworms. Both of these major cotton
pests have adapted to commonly used chemical insecticides, making them less
effective, notes Teal.
Normally, these insects produce pheromones--in this case, female sex odors
released to attract males for mating--for 3 hours. Teal demonstrated that some
of the analogs caused both species to produce pheromones nonstop for 20 hours.
"This strategy could cause the insect to run out of pheromone-producing
chemicals and make it impossible for the insect to attract mates," says
This work represents a significant milestone in developing environmentally
friendly pest insect management strategies. Nachman, Teal, and Holman are
pursuing patents on all the compounds.--By
Linda Cooke McGraw,
Agricultural Research Service Information Staff, 1815 North University Street,
Peoria, IL 61604, phone (309) 681-6530.
Ronald J. Nachman and G. Mark
Holman are in the USDA-ARS Veterinary Entomology Research Unit, 2881 F&B
Rd., College Station, TX 77845; phone (409) 260-9315, fax (409) 260-9377.
Peter E. A. Teal is in
the USDA-ARS Chemistry Research Unit,Center
for Medical, Agricultural, and Veterinary Entomology, 1700 SW 23rd Dr.,
Gainesville, FL 32604; phone (352) 374-5788, fax (352) 374-5707, e-mail
"Synthetics Mimic Natural Brain Chemicals " was published
in the May 1998 issue of Agricultural Research magazine. Click here to see this
issue's table of contents.