Bugs’ Brain Chemicals Could Be Powerful Weapon Against Crop Pests

Artificial copies of insects’ brain chemicals could play an important role in preventing the pests from munching on crops. Agricultural Research Service scientists have developed synthetic brain chemicals that disrupt insect molting, mating and other vital body functions.

These lab-made chemicals mimic natural chemicals in an insect’s brain. The chemicals, in proper balance, help the insect grow and reproduce. But too much--or not enough-- spells trouble. ARS scientists say the goal is to develop commercial products containing these artificial chemicals, called neuropeptides, that farmers can spray onto crops to short-circuit corn earworms and other pests. The scientists say these products could be developed in about five years.

Inside an insect’s brain, neuropeptides act as chemical messengers to stimulate life- sustaining functions. These messengers are composed of amino acids, the building blocks of protein. The neuropeptides control molting (shedding of the insect’s skin), mating, digestion and water balance.

The biggest challenge the researchers faced was to get the mimics through the insects’ tough skin or cuticle. They solved this problem by replacing some of the amino acids with a combination of boron, carbon and other chemicals. This new molecule became greasy just like the insects’ cuticle, thus making absorption into the insect possible.

Then came the real test. On tobacco budworm and cotton bollworm skin, the scientists dabbed their mimic of a neuropeptide that controls the production of pheromones-- female sex odors that attract males for mating. Normally, these insects produce pheromones for three hours. But adding the mimic fueled nonstop pheromone production for 20 hours, meaning the females could be running on empty at mating time.

This research is important because both of these major cotton pests have adapted to commonly used chemical insecticides. A story about the research appears in the May issue of Agricultural Research magazine. The story also is on the World Wide Web at:

http://www.ars.usda.gov/is/AR/archive/may98/synt0598.htm

Scientific contact: Ronald J. Nachman, ARS Veterinary Entomology Research Unit, College Station, TX 77845, phone (409) 260-9315, fax (409) 260-9377, nachman@acs.tamu.edu.