COI Haplotyping and Comparative Microbiomics of the Peach Fruit Fly, an Emerging Pest of Egyptian Olive Orchards

SIMPLE SUMMARY: The peach fruit fly is an economically relevant agricultural insect pest infesting many types of fruit and vegetables. It originated from the Indian subcontinent and was spread across the Middle East to Egypt and Sudan. Due to changing climatic conditions, its further spread in the Mediterranean region is highly probable. The present study demonstrated that the peach fruit fly has adapted to olives as a new host plant. This poses a potentially serious threat to olive cultivation in Northern African and Southern European countries. The present study used molecular genetic methods to investigate the diversity of peach fruit fly populations from Egyptian olive orchards in order to understand if adaptation to the new host plant occurred once or several times. Moreover, as it is well known that fruit flies carry symbiotic bacteria, termed “bacterial microbiome”, that help them to adapt to changing environmental conditions, the present study has compared the bacterial microbiome of peach fruit flies developing in olives and in other fruits. Several changes in the microbiome composition were identified. This knowledge can help to understand how similar adaptations happen and to develop agents or strategies for biological control of the peach fruit fly. ABSTRACT: The peach fruit fly, Bactrocera zonata (Tephritidae), is economically relevant as a highly polyphagous pest infesting over 50 host plants including commercial fruit and horticultural crops. As an invasive species, B. zonata was firmly established in Egypt and holds potential to spread further across the Mediterranean basin. The present study demonstrated that the peach fruit fly was found multiplying in olive orchards at two distant locations in Egypt. This is the first report of B. zonata developing in olives. COI barcoding has revealed evidence for high diversity across these peach fruit fly populations. These data are consistent with multiple rather than a single event leading to both peach fruit fly invasion to Egypt and its adaptation to olive. Comparative microbiomics data for B. zonata developing on different host plants were indicative for microbiome dynamics being involved in the adaptation to olive as a new niche with a potential adaptive role for Erwinia or Providencia bacteria. The possibility of symbiont transfer from the olive fruit fly to the peach fruit fly is discussed. Potentially host switch relevant bacterial symbionts might be preferred targets of symbiosis disruption strategies for integrated pest management or biological control of B. zonata.