Effects of soil nutrient enrichment on trophic interactions between herbivorous insects and foliage spiders in Patagonian forests

MARTÍNEZ, LUCÍA C.; PANCHUK, JUSTINA; HAEDO, JOANA PAOLA; POMPOZZI, GABRIEL; PÉREZ MÉNDEZ, NÉSTOR; FIORONI, FACUNDO; GARIBALDI LUCAS A.; MARRERO, HUGO J.

OECOLOGIA

SPRINGER

Lugar: Berlin; Año: 2025 vol. 207 p. 66 - 66

0029-8549

The addition of nutrients to soil can induce changes through "bottom-up" effects in soil-plant29 animal interactions, impacting higher levels in food chains. Changes in foliar nutrient content30 may influence diets of herbivorous insects, subsequently altering their feeding rates and31 abundance. Spiders established in foliage rely on these insects for sustenance; therefore,32 fluctuations in the abundance of herbivorous insect communities ultimately determine the33 population dynamics of their spider predators. We established a long-term field experiment to34 investigate the effects of nutrient addition of N (nitrogen), P (phosphorus), K (potassium) and35 their combinations on plant-arthropod interactions. We carried out sampling in 32 plots under36 different nutrient addition treatments, where we captured herbivorous insects and spiders on37 Nothofagus antarctica plants, the most abundant plant species in the Patagonian scrubland. Our38 results showed that foliar nutrient concentrations had cascading effects throughout the forest39 food chain. Herbivorous insects (Diptera, Coleoptera, Hemiptera and Lepidoptera orders)40 exhibited a positive response to the increased foliar phosphorus content, resulting in higher41 population densities. Additionally, we found a strong positive relationship between herbivorous42 insect abundance and spider abundance. Our findings indicate that variations in the availability43 of soil nutrients play a crucial role in defining the structure of predator-prey interactions in44 forest ecosystems.