Rendering the Inedible Edible: Circumvention of a Millipede's Chemical Defense by a Predaceous Beetle Larva (Phengodidae)
The larva of the phengodid beetle, Phengodes laticollis, feeds on the millipede, Floridobolus penneri, without risking exposure to the repellent benzoquinones ordinarily ejected by the millipede from its defensive glands when attacked. The phengodid subdues the millipede by piercing the millipede’s integument with its hollow sickle-shaped mandibles and apparently injecting gastric fluid. The infusion abruptly paralyzes the millipede, which thereby is prevented from discharging its glands. As the phengodid then imbibes the liquefied systemic contents of the dead millipede, the millipede’s benzoquinones remain harmlessly confined to the glands, prevented from diffusing into the millipede’s body cavity by the glands’ impervious cuticular lining. At the end of the meal only the millipede’s skeletal armor and glandular sacs remain uneaten. Analysis of such discarded sacs showed these to contain benzoquinones in amounts commensurate with those present in replete glands of living millipedes.