Because the alkaloids are cumulative hepatotoxins and carcinogens, they are often involved in cases of livestock poisoning. Interactions of pyrrolizidine alkaloids and insects Pyrrolizidine alkaloids are feeding deterrents and insecticidal for many species of insects. Other insects that feed on the plants, excrete the alkaloids and don't sequester them. Yet other insects sequester the alkaloids. Both larvae and adults of the Danainae may consume food plants with pyrrolizidine alkaloids, but only adult Ithomiinae are able to obtain the alkaloids.
Some moths store pyrrolizidine alkaloids without change.
Larvae of the cinnabar moth, Tyria jacobea , accumulate these alkaloids and become distasteful to predators. All stages of the moths have warning coloration. Many other insects consume plants with these alkaloids and a number are involved in biological interactions that include the alkaloids. Monarch butterflies, Danaus plexippus , contain pyrrolizidine alkaloids from larval feeding, but don't appear to use these compounds as pheromones. Other Danaus species convert ingested pyrrolizidine alkaloids into compounds such as danaidone, danaidal, and hydroxydanaidal that are released as a component of hairpencil secretions.