Detection of Bactrocera oleae (Diptera: Tephritidae) DNA in the gut of the soil species Pseudoophonus rufipes (Coleoptera: Carabidae)

Alice Albertini,Paula Baptista,José A Pereira,Fátima Martins,Teresa Lino-Neto,Ruggero Petacchi,Sónia A P Santos

doi:10.5424/sjar/2018163-12860

Abstract

Pest control service provided by natural enemies of Bactrocera oleae, the key pest of the olive tree, is nowadays recognized as fundamental. B. oleae has developed resistance to common insecticides, and negative effects both on consumers’ health and non-target species are the major drawbacks of conventional control strategies. Carabid beetles are potential B. oleae pupae predators, but their predation on field still need to be assessed. We tested adult Pseudoophonus rufipes, a species known to be active in olive orchard when pest pupae are abundant in the soil, in order to detect B. oleae pupae consumption at different post feeding times for both male and female carabids. An already existing protocol was used for detecting B. oleae mtDNA sequences of the cytochrome oxidase subunit I gene in carabids’ gut, and its versatility improved. B. oleae mtDNA was detected up to 20 h after pupa ingestion with a high percentage of success, without significant differences between sexes and pair primers used. Prey DNA extraction was tested from both dissected and non-dissected carabids, obtaining comparable results. The trapping system used to collect carabids for molecular assays and the new elements introduced in the protocol represent cost-effective solutions that may be beneficial for future laboratory trials and, mostly, for the analysis of field-collected predators. Fostering the investigation of soil predators in olive orchard may increase the design of conservation control strategies against B. oleae.

Highlights

The olive tree (Olea europaea L.) is one of the main crops in the Mediterranean basin, where the region alone produces 91.2% and consumes 72% of the world’s olive oils (International Olive Oil Council, http://www.internationaloliveoil.org, data updated to 2015/2016 crop year)
We tested adult Pseudoophonus rufipes, a species known to be active in olive orchard when pest pupae are abundant in the soil, in order to detect B. oleae pupae consumption at different post feeding times for both male and female carabids
There is a general increasing interest in the tested species P. rufipes, which has already been proposed both as pest control agent and useful seed consumer (Wallinger et al, 2015). Since it is active in olive orchards when pest pupae are more abundant in the soil (Albertini et al, 2017), P. rufipes may be used as a good model species for testing its efficiency as B. oleae natural enemy

Summary

Introduction

The olive tree (Olea europaea L.) is one of the main crops in the Mediterranean basin, where the region alone produces 91.2% and consumes 72% of the world’s olive oils (International Olive Oil Council, http://www.internationaloliveoil.org, data updated to 2015/2016 crop year). Losses up to 80% of the oil value and 100% of some table cultivars are caused by the obligate olive key pest, the olive fruit fly Bactrocera oleae (Rossi, 1790) (Diptera: Tephritidae) (Daane & Johnson, 2010; Malheiro et al, 2015). A predicted 2°C global warming in the Mediterranean Basin between 2030 and 2060 (Giannakopoulos et al, 2009) is alerting bioeconomics and producers, as interactions between olive and B. oleae are expected to be enhanced (Ponti et al, 2014). For the conservation of olive orchard agroecosystem, economy and cultural heritage, holistic strategies are urgently needed (Ponti et al, 2016; Marchini et al, 2017)

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Results

Conclusion