Study shows single insecticide application can kill 3 cockroach g...( WEST LAFAYETTE Ind. - One dose of an...)

WEST LAFAYETTE, Ind. - One dose of an insecticide can kill three generations of cockroaches as they feed off of each other and transfer the poison, according to Purdue University entomologists who tested the effectiveness of a specific gel bait.

It is the first time that scientists have shown that a pest control bait will remain effective when it's transferred twice after the first killing dose, said Grzegorz "Grzesiek" Buczkowski, assistant professor of entomology. Passing the insecticide from one cockroach to the next is called horizontal transfer.

"Our findings are exciting because cockroaches are difficult to control since they multiply so rapidly," Buczkowski said. "They are especially bad in urban housing, and they can cause health problems."

It's difficult to find and rid areas of the insects because cockroaches come out at night and live in inaccessible places, he said. They invade places where they easily can find plenty of food and water. In addition, cockroaches are attracted to where other cockroaches are by a chemical compound, called pheromones, that animals secrete and which influences other cockroaches' behavior.

In a laboratory study, the scientists used German cockroaches, the most common household species in the United States, to test a DuPont product with the active ingredient indoxacarb. Although the researchers only studied indoxacarb, Buczkowski said it's possible other insecticides also may have three-generation horizontal transfer kill capabilities.

In the first transfer of the insecticide from a dying adult to the youngest stage nymphs, an average of 76 percent of these cockroaches also succumbed to the indoxacarb-containing excretions from the dying cockroaches, the researchers report in the June issue of the Journal of Economic Entomology. In the third stage of transfer, or tertiary kill, an average of 81 percent of the adult male cockroaches that ate the dead nymphs' bodies a
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