Ecological indices of phytophagous Hemiptera and their natural enemies on Acacia auriculiformis (Fabales: Fabaceae) plants with or without dehydrated sewage sludge application in a degraded area.

Luan Rocha Dourado,Jose Cola Zanuncio,Regynaldo Arruda Sampaio,Marcus Alvarenga Soares,Jesusa Crisostomo Legaspi,Farley William Souza Silva,Germano Leão Demolin-Leite,Gustavo Leal Teixeira,Tunira Bhadauria

doi:10.1371/journal.pone.0237261

Abstract

Soil fertilization with dehydrated sewage sludge (DSS) accelerates the recovery process of degraded areas by improving nutrient concentration, and favors the development of trophic webs with pioneer plants such as Acacia auriculiformis A. Cunn. ex Beth (Fabales: Fabaceae), phytophagous Hemiptera, predators, and protocooperanting ants. This study aimed to evaluate the development and production of A. auriculiformis litter with or without dehydrated sewage sludge application and the ecological indices of sucking insects (Hemiptera), their predators and protocooperating ants, as bioindicators, in a degraded area for 24 months. Complete randomization was applied for two treatments (with or without application of dehydrated sewage sludge) in 24 replications (one repetition = one plant). We evaluated the number of leaves/branch and branches/plant, percentage of soil cover (litter), ecological indices of phytophagous Hemiptera, their predators, and protocooperating ants. The plants of A. auriculiformis, that were applied with dehydrated sewage sludge, had superior development when compared to plants where DSS were not applied. The highest abundance and richness of phytophagous Hemiptera species and Sternorrhyncha predators occurred on A. auriculiformis plants that were applied with dehydrated sewage sludge. The increase in richness of species of protocooperanting ants that established mutualistic relationships positively influenced the phytophagous Hemiptera. The use of A. auriculiformis, with application of dehydrated sewage sludge, can increase recovery of degraded areas due to its higher soil cover (e.g., litter) and results in higher ecological indices of phytophagous Hemiptera and their predators.

Highlights

IntroductionTropical soils (eg., Brazil), in general, are highly weathered, have poor chemical quality and fragile macrostructure [1]
Tropical soils, in general, are highly weathered, have poor chemical quality and fragile macrostructure [1]
The plants of A. auriculiformis treated with dehydrated sewage sludge had higher numbers of leaves/branch, branches/plant and percentage of soil cover (P < 0.05) (Table 1)

Summary

Introduction

Tropical soils (eg., Brazil), in general, are highly weathered, have poor chemical quality and fragile macrostructure [1]. The tropical climate, with high temperatures and humidity, accelerates the degradation of soil organic matter [2]. These factors, combined with poor soil management, forest clearing and burning, intensive mechanization, and grazing, promote changes in ecosystems at a faster rate than the natural regeneration capacity [2]. Depending on the intensity of soil degradation, the use of restoration techniques is suggested for fauna and flora rehabilitation [4] In this context, species of the genus Acacia (Fabales: Fabaceae) may be useful due to their rapid growth and the capacity for biological nitrogen fixation (BNF) in association with symbiotic bacteria [5]. A. auriculiformis provides other ecosystem services such as moisture retention, potassium deposition, soil organic carbon (litter) and heavy metal phytoextraction with mycorrhizal associations [8, 9]

Objectives

Results

Discussion

Conclusion