By Susan Milius
Beware the caterpillar offering a juicy treat. Sips tweak ant brain chemistry, lulling the insects into neglecting their own colony in favor of hanging around the source of the marvelous droplets.
Effects on the brain help Narathura japonica caterpillars recruit a corps of ant bodyguards, says chemical ecologist Masaru K. Hojo of Kobe University in Japan. In lab tests, ants sipping these secretions scurried around less on their own initiative than normal ants do. Yet the low-key ants burst into frenzies of defensive aggression when the caterpillar showed alarm. Analyses of ant brains suggest that the caterpillar droplets change the concentrations of the chemical messenger dopamine in the brain. And that change may turn passersby into protectors, Hojo and his colleagues suggest in the Aug. 31 Current Biology.