Alien tree’s sugary SOS exploited by thieving tramp ant: unidirectional benefit in a tritrophic mélange
Emily Elizabeth Jones, Natalie Christina Martin
Triadica sebifera (Euphorbiaceae), a centuries old invader of southern ecosystems, was virtually free from natural enemies until the specific, hypermetamorphic moth Caloptilia triadicae (Lepidoptera: Gracillariidae) appeared in 2004. Simultaneously, populations of the destructive tawny crazy ant, Nylanderia fulva (Hymenoptera: Formicidae), spread cospatially across the southeast. To examine potential interactions among these species, we sought answers to these questions: 1) does Caloptilia induce extrafloral nectar production in Triadica; 2) does N. fulva consume nectar, larvae, or both; and 3) does N. fulva provide indirect defense to the tree, or to its attacker? To understand these interactions, and their implications for southern ecosystems, we conducted a series of lab, greenhouse, and field experiments in coastal Texas. In response to herbivory by Caloptilia, potted Triadica saplings strongly induced extrafloral nectar production. Percent leaf damage explained 57% of the variation in cumulative nectar volume (p<.0001), and nectar volume on saplings with >20% of leaves damaged was significantly greater than on controls (p=0.0005). Nylanderia fulva exploited available nectar resources without attacking Caloptilia larvae. On potted saplings, nectar volume was significantly lower when ants were present (p=0.008), while no differences were observed in Caloptilia survivorship (p=0.56). Likewise, no differences in Caloptilia abundance or parasitism rates were observed when ants were excluded from naturally recruited Triadica saplings (p=0.97;p=0.8). Large Caloptilia infestations reduced trunk elongation in Triadica saplings (R2=0.32, p<.0001), but had no effect on leaf production, biomass, or survivorship. Because Triadica saplings supplied N. fulva workers a carbohydrate resource while sustaining heavy damage, and because neither Triadica nor Caloptilia benefited from worker foraging, N. fulva was the only beneficiary in this alien, tritrophic interaction.
Kathleen A. Kargl, Chelse M. Prather
Primary Advisor's Department
Stander Symposium project
"Alien tree’s sugary SOS exploited by thieving tramp ant: unidirectional benefit in a tritrophic mélange" (2019). Stander Symposium Projects. 1594.