Ecological indexes of arthropods on Sapindus saponaria (Sapindaceae) plants fertilized with urban dehydrated sewage sludge

Introduction: Soil degradation and land abandonment caused by intensive agriculture threaten ecosystem functions, yet conservation programs often overlook arthropods such as insects and spiders and their essential roles in food webs. Aims/Methods: We evaluated the effects of urban dehydrated sewage sludge on Sapindus saponaria (Sapindales) by comparing fertilized (T1) and unfertilized (T2) plants in a degraded area of Montes Claros, Minas Gerais, Brazil. We measured leaves per branch, branches per plant, ground cover, and arthropod abundance, diversity and richness over 24 months under both treatments. Results Plants receiving sewage sludge were significantly higher in numbers of leaves per branch, branches per plant and percentage ground cover (all p  < 0.05). Arthropod abundance, diversity and species richness, including chewing insects, predators and total arthropod assemblages, were also greater in the fertilized treatment (all p  < 0.05). Discussion Urban sewage sludge, a nutrient-rich organic amendment, enhances both plant growth and the structure of arthropod communities, likely by increasing habitat complexity and resource availability during ecosystem recovery. Implications for insect conservation: Application of dehydrated sewage sludge in restoration schemes can boost arthropod biodiversity and support trophic interactions, contributing to more resilient insect populations in degraded tropical habitats.