Habitat Alteration Reshapes the Abundance Structure of Neuroptera Assemblages in the Monte Drylands of Argentina: Implications for Conservation

Abstract

1. Habitat alteration is a major driver of insect decline and is often expected to homogenize communities. Its effects on Neuroptera, a predatory order of value for biological control, remain poorly known in South American drylands. 2. We compared neuropteran assemblages between ravines with native vegetation and small urban-rural oases in the Monte of Mountain Ranges and Ravines ecoregion of Argentina, a poorly sampled region with high endemism, using light-trap samples, coverage-based Hill numbers, and the partition of beta diversity into turnover and nestedness. 3. We detected no difference between habitats in species richness, compositional variability among sites, or the turnover and nestedness components of beta diversity. Most species were shared, and beta diversity was dominated by turnover among localities. 4. Differences were restricted to the abundance structure of the assemblages. Native ravines were dominated by two Ungla species, which drove the compositional difference and were the taxa most associated with native vegetation, whereas the oases supported more even assemblages with larger shares of Chrysoperla argentina, Hemerobiidae, and Coniopterygidae. These patterns persisted after excluding the largest samples and accounting for sampling campaign. 5. Small oases embedded in native vegetation did not show the homogenization expected under habitat alteration, probably because of their proximity to native habitats. Native ravines act as a reservoir of the regional species pool and of candidate indicator species, and conserving a network of ravines is a priority to sustain neuropteran diversity and the natural enemies that may contribute to pest regulation in the oases.