Cover Cropping Alters the Diet of Arthropods in a Banana Plantation: A Metabarcoding Approach

Dawn Sywassink Luthe,Gregory Mollot,Pierre Lefeuvre,Jean-François Martin,Françoise Lescourret,Sylvain Piry,Elsa Canard,Philippe Tixier,Pierre-François Duyck

doi:10.1371/journal.pone.0093740

Abstract

Plant diversification using cover crops may promote natural regulation of agricultural pests by supporting alternative prey that enable the increase of arthropod predator densities. However, the changes in the specific composition of predator diet induced by cover cropping are poorly understood. Here, we hypothesized that the cover crop can significantly alter the diet of predators in agroecosystems. The cover crop Brachiaria decumbens is increasingly used in banana plantations to control weeds and improve physical soil properties. In this paper, we used a DNA metabarcoding approach for the molecular analysis of the gut contents of predators (based on mini-COI) to identify 1) the DNA sequences of their prey, 2) the predators of Cosmopolites sordidus (a major pest of banana crops), and 3) the difference in the specific composition of predator diets between a bare soil plot (BSP) and a cover cropped plot (CCP) in a banana plantation. The earwig Euborellia caraibea, the carpenter ant Camponotus sexguttatus, and the fire ant Solenopsis geminata were found to contain C. sordidus DNA at frequencies ranging from 1 to 7%. While the frequencies of predators positive for C. sordidus DNA did not significantly differ between BSP and CCP, the frequency at which E. caraibea was positive for Diptera was 26% in BSP and 80% in CCP; the frequency at which C. sexguttatus was positive for Jalysus spinosus was 14% in BSP and 0% in CCP; and the frequency at which S. geminata was positive for Polytus mellerborgi was 21% in BSP and 3% in CCP. E. caraibea, C. sexguttatus and S. geminata were identified as possible biological agents for the regulation of C. sordidus. The detection of the diet changes of these predators when a cover crop is planted indicates the possible negative effects on pest regulation if predators switch to forage on alternative prey.

Highlights

Agriculture faces the challenges of providing more food and energy while adapting to climate change and mitigating environmental impacts
We demonstrated that the addition of a new primary resource in the agroecosystem modified the diet for some of the predators
The efficiency of the mini-c oxidase I (COI) PCR was highly variable depending on the predator taxa examined, and this remains a major problem in achieving comprehensive identification of the prey ingested by a predator

Summary

Introduction

Agriculture faces the challenges of providing more food and energy while adapting to climate change and mitigating environmental impacts. The regulation of crop pests through top-down and bottom-up effects remains a potential alternative to reduce the ecological imprints of agroecosystems while maintaining production [2]. This regulation could rely on the management of primary resources, such as the addition of cover crops [3]. The larger the densities of predators, the higher the consumption of herbivore pests - provided that the pest remains a favourite prey [4,5] It follows that designing environmentally friendly cropping systems requires a clear understanding of food web functions

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