Study finds cockroaches not so resilient after all

June 24th, 2008 - 5:32 pm ICT by IANS  


Washington, June 24 (IANS) A single dose of an insecticide can kill three generations of cockroaches for good as they feed off one another and transfer poison, according to a study. A pest control bait will remain effective when it’s transferred twice after the first killing dose, said Grzegorz Buczkowski of Purdue University, who led the study.

“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.”

Cockroaches 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’ behaviour.

In a lab study, the scientists used German cockroaches, the most common household species, to test a DuPont product with the active ingredient indoxacarb.

Although 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.

In the third stage of transfer, an average of 81 percent of the adult male cockroaches that ate the dead nymphs’ bodies also died. Both statistics were taken 72 hours after the insects were exposed to a cockroach already affected by indoxacarb.

“Cockroaches moult their skin as they go from one nymph stage to the next, and there is a huge accumulation of the skin left in the areas where they live,” Buczkowski said.

“The dead skin becomes airborne and causes allergies and asthma. It’s really the biggest problem with cockroaches.”

The findings of the study have appeared in latest issue of the Journal of Economic Entomology.

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