Poison Avoidance

Organisms of all kinds rapidly adapt. The more primitive, the more quickly evolution creates a solution.

Human pests are exemplary. In response to assault of toxic baits by humans, who consider their home not a proper home for roaches, German cockroaches rapidly adapted. The sugar glucose, put in baits to attract, instead took on a bitter taste, which the roaches avoided.

Instead of taste buds, cockroaches have taste hairs on many parts of their body. But the taste mechanism is much the same. A sensed molecule triggers a signal to the brain, which deciphers substance quality and decides a response.

Glucose is a come-hither sweet to countless life forms, and a ubiquitous biological fuel. But roaches at the genetic level adaptively “learned” that glucose out of context to a natural sugar is a trap. 

This adaptation took less than a decade from the time glucose baits were introduced. The evolutionary mechanism at the cellular and genetic levels remains a mystery.

“We lose baits all the time.” ~ American entomologist Grzegorz “Grzesiek” Buczkowski

Mosquitoes are another highly unpopular pest. They quickly evolved not to linger on walls that have been treated with insecticide. Instead, untreated ceilings are preferred.


James Gorman, “A bitter/sweet shift in cockroach defenses,” The New York Times (23 May 2013).

Ayako Wada-Katsumata et al, “Changes in taste neurons support the emergence of an adaptive behavior in cockroaches,” Science 340(6135): 972–975 (24 May 2013).

Ishi Nobu, The Elements of Evolution (pre-publication).