Spittlebug nymphs probably don’t have much of a social life – they cover themselves in a froth made of their excrement. But it’s a life-saving strategy that would otherwise leave them susceptible to the nymph-chewing jaws of predatory ants. After consuming sap from their favorite plant, the eastern white pine, spittlebug nymphs completely engulf themselves in foam containing at least five ant-repellant chemicals. As the predatory ants approach, taste buds in their probing antennae apparently find spittlebug fecal foam far from flavorful and proceed to wipe off the offending substances rather than make a meal of the nymph. The ant-repellant compounds also appear to be non-irritating to living tissue which would make them particularly interesting models for new pesticides.
Artist: Emily Harrington. Copyright: All rights reserved. See gallery for details.
“Nymphs of the cercopid Aphrophora cribrata cover themselves with a frothy exudate while ingesting sap from their preferred host plant, the eastern white pine, Pinus strobus. Chemical analyses of froth collected from A. cribrata nymphs revealed an array of metabolites belonging to five chemical classes, including fatty acid-derived alcohols, c-lactones and a single 1-monoacylglycerol, as well as the polyol pinitol and the polyhydroxyalkanoate, poly-3-hydroxybutyrate. Bioassays showed the natural A. cribata froth, as well as a synthetic mixture comprised of representative compound classes identified therein, to be repellent to ants but largely devoid of topical irritancy in tests with cockroaches.” (del Campo et al. 2011:1)
“[T]he repellency observed towards ants derives primarily from contact with anterior taste receptor organs.” (del Campo et al. 2011:2)
“[T]he natural A. cribrata froth effectively deterred the ant, F. [Formica] exsectoides. Ants contacting the froth-coated and recoated cercopid nymphs were over 90% deterred, while ants contacting the defrothed nymphs were significantly less deterred from attack.” (del Campo et al. 2011:5)
“The synthetic mixture comprising the five metabolite classes identified in the natural froth was an effective deterrent against predatory ants.” (del Campo et al. 2011:5)