Symbiosis disruption in the olive fruit fly, Bactrocera oleae (Rossi), as a potential tool for sustainable control.

BACKGROUND: The olive fruit fly Bactrocera oleae (Rossi) (OLF) is a major agricultural pest, whose control primarily relies on the use of chemical insecticides. Therefore, the development of sustainable control strategies is highly desirable. The primary endosymbiotic bacterium of the OLF, "Candidatus Erwinia dacicola", is essential for successful larval development in unripe olive fruits. Then, targeting this endosymbiont with antimicrobial compounds may result in OLF fitness reduction and may exert a control action of its natural populations. RESULTS: Here we evaluate the impact of compounds with antimicrobial activity on OLF endosymbiont. Copper Oxychloride (CO) and the fungal metabolite Viridiol (Vi), produced by Trichoderma spp., were used. Laboratory bioassays were carried out to assess the effect of the oral administration of these compounds on OLF fitness and molecular analyses (qPCR) were conducted to measure the load of OLF-associated microorganisms in treated flies. CO and Vi were both able to disrupt the symbiotic association between OLF and its symbiotic bacteria, determining a significant reduction of the endosymbiont and gut microbiota load as well as an OLF fitness decrease. CO had a direct negative effect on OLF adults. Conversely, exposure to Vi significantly undermined the larval development of the treated females' progeny but did not show any toxicity in OLF adults. CONCLUSIONS: These results provide new insights on the symbiotic control of the OLF and pave the way toward the development of more sustainable strategies of pest control based on the use of natural compounds with antimicrobial activity. This article is protected by copyright. All rights reserved.