Inhibition of insect acetylcholinesterase by the potato glycoalkaloid alpha-chaconine

Homogenates from several insect species were assayed for inhibition of acetylcholinesterase by the potato glycoalkaloid alpha-chaconine. Colorado potato beetle acetylcholinesterase was up to 150-fold less sensitive than other species tested. Acetylcholinesterase from an insecticide-resistant strain of Colorado potato beetles was more sensitive to inhibition than the susceptible strain. Most insect species tested had inhibitory concentrations causing a 50% reduction in activity in the 5 to 40 microM range. Sensitive insect acetylcholinesterases were similar to mammalian cholinesterases in their response to alpha-chaconine. The results indicate that pesticides and host plant resistance factors may interact at the same target. Changes in the target due to selection pressure from either pesticides or host plant resistance factors could affect the efficacy of both control strategies.