Methodological considerations in discriminating olive-orchard management type using olive-canopy arthropod fauna at the level of order

Abstract

The cultivation of the olive tree (Olea europaea L.) has great importance in the entire Mediterranean basin, so that the implementation of organic practices in their management directly affects the sustainability of the agricultural system. Bioindication with arthropods can help to detect the different agricultural practices. In this work, we analyse the most appropriate methodology for discriminating between management using arthropods at the taxonomic level of order, with the novelty of taking into account the weather conditions to select the sampling dates. Between 12 and 15 sampling stations (depending on the year) were selected from olive orchards belonging to organic, conventional non-tillage, and strict conventional management, being sampled by beating the canopy fortnightly in the spring-summer period of 2007, 2008 and 2009. Organic management was more abundant and richer than the rest for the three years. Most groups with significant differences in terms of relative abundance were more abundant in organic orchard, except Neuroptera. Finally, different discriminant methods were evaluated (Linear Discriminant Analysis, Multiple Discriminant Analysis, and Support Vector Machine) with several different data sets. The discriminant analysis with interannual variability reached 97.9% accuracy in differentiating between organic and non-organic management using the LDA method, considering the taxa with significant differences from the abundance, excluding pests, and using samples with more uniform and stable weather patterns (late summer).Additional key words: bioindication; conventional; discriminant analysis; meteorological conditions; non-tillage; organic. Abbreviations used: CON (conventional production); FR% (percentage of individuals recorded); K-W (Kruskal-Wallis nonparametric test); LDA (Linear Discriminant Analysis); m (slope of the line); MDA (Multiple Discriminant Analysis); Me (median); n (number of sample units used); n (m=0.1) (number of samples required for a slope of 0.1); N (absolute abundance of arthropods); NonORG (non-organic production); NS (not significant); NT (conventional non-tillage production); ORG (organic production); Q1 (first quartile); Q3 (third quartile); SD (standard deviation); S obs (observed number of orders); SVM (Support Vector Machine); TNO (total number of orders); X̅ ORG , X̅ NT or X̅ CON (mean abundance per station of each management type).Citation: Jerez-Valle, C.; García-López, P. A.; Pascual, F. (2015). Methodological considerations in discriminating olive-orchard management type using olive-canopy arthropod fauna at the level of order. Spanish Journal of Agricultural Research, Volume 13, Issue 4, e0304, 14 pages. http://dx.doi.org/10.5424/sjar/2015134-6588.This work has one supplementary figure and two supplementary tables published online alongside the electronic version of the article.

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