Maybe science has misunderstood the dining style of big monarch butterfly caterpillars. What insect watchers have called defense against the toxic latex a milkweed plant oozes may not be avoidance at all. Instead of dodging the plants’ sticky, white toxic goo, the plump, older caterpillars could be gorging on it.
Caterpillars, however, can get around milkweed sticky traps by nipping leaf stalks and then waiting for the latex channels to bleed out. A swath of killer leaf becomes a harmless vegetable.
For older caterpillars strong enough to risk glue, Petschenka argues, those bleed-out cuts can do more than disarm a leaf. By this stage, the monarch caterpillars feast on the latex itself. Offering them a pipette loaded with latex to suckle showed they drink it readily and build up their own defensive reserves of milkweed toxins, he and entomologists Anja Betz and Robert Bischoff, also at Hohenheim, reported February 21 in Proceedings of the Royal Society B.
The older caterpillars dip their mouthparts in latex “like a little cat drinking milk,” Petschenka says.
2024-03-08 10:45:00
Original from www.sciencenews.org
