Targeted cannibalism of queens mediated by worker signals in fire ants

Ants employ a wide range of communication systems to coordinate colony functions, with chemical signals being the most extensively studied. While investigating social regulation in the invasive fire ant Solenopsis invicta, we discovered a striking behavior: under food-deprived conditions, workers frequently cannibalize a high proportion of virgin queens. Our experiments revealed that this behavior is triggered by nutritional stress and mediated by a specific vibrational signal (stridulation) produced by workers and directed at young queens. Chemical analyses showed no significant differences in cuticular hydrocarbons between targeted and non-targeted queens, providing no evidence that chemical cues are responsible for this behavior. In contrast, playback experiments demonstrated that queen cannibalism is directly induced by vibrational signals. These findings uncover a previously unrecognized role for stridulation in regulating social behavior and challenge the notion that non-chemical communication is secondary in ants.