A tritrophic interaction model for an olive tree pest, the olive moth — Prays oleae (Bernard)

Sonia Pappalardo,María Villa,Sónia A.P Santos,Jacinto Benhadi-Marín,José Alberto Pereira,Ezio Venturino

doi:10.1016/j.ecolmodel.2021.109776

Abstract

The olive tree (Olea europaea L.) is among the oldest and most widespread crops in the Mediterranean basin. Portugal is the third olive producer in the European Union, and Trás-os-Montes region, located in northeastern Portugal, is the second Portuguese producing olive region.The olive moth, Prays oleae (Bernard) (Lepidoptera: Praydidae) is a key olive pest in Trás-os-Montes. This pest is a natural host/prey of several organisms which include larvae of generalist and specialist parasitoids as well as generalist predators and entomopathogens. Its most abundant parasitoid is the specialist Ageniaspis fuscicollis (Dalman) (Hymenoptera: Encyrtidae) and this, in Trás-os-Montes region, is commonly followed by the facultative hyperparasitoid Elasmus flabellatus (Fonscolombe) (Hymenoptera: Eulophidae). Spiders represent a relevant group of generalist predators in olive agroecosystems and encompass an important predatory action in agroecosystems as well as an ability to reduce the populations of various insect pests. In this context, a mathematical model, considering the population of the olive moth, the two parasitoids populations and the spider population as the variables in our system, was constructed. The ecosystem steady states for feasibility and stability were assessed. The possible pesticide effects, that represent essentially extra mortality rates for each one of the insect populations, and potential abundance variations on their populations under a climate change scenario were included. Results indicate that the most important natural control agent is A. fuscicollis but in certain conditions E. flabellatus or spiders may be relevant contributors for the pest reduction. This approach may provide a useful tool to assist the field researchers on this pest system and its management.

Highlights

The olive tree (Olea europaea L.), one of the oldest and most widespread crops, has characterized economically, socially and culturally the populations of the Mediterranean basin
The olive tree is attacked by several pests that result in severe economical losses
Our goal is to develop a mathematical model to generate population behavioral predictions under different abundance scenarios, resulting from the potential effects of climate change, for the various agents involved in the trophic system under consideration

Summary

Introduction

The olive tree (Olea europaea L.), one of the oldest and most widespread crops, has characterized economically, socially and culturally the populations of the Mediterranean basin. Nowadays, it is cultivated in all regions with climatic conditions that allow its establishment (Bartolini and Petruccelli, 2002). Its adult flight period occurs at the end of the spring, laying the eggs of the carpophagous generation on the olive calyx. The carpophagous generation larvae bore into the olive stone and feed on the seed. At the end of the summer and beginning of the autumn, adults emerge and lay the phyllophagous generation eggs on the olive leaves. The phyllophagous larvae feed on the leaves and dig tunnels into them, where they overwinter until the following spring (Arambourg and Pralavorio, 1986)

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