# Integrative Longitudinal Study of ‘Candidatus Phytoplasma pyri’ Epidemic Dynamics Using Molecular and Remote Sensing Approaches

## TL;DR

This study combines field surveys, molecular analysis, and remote sensing to track the spread of a severe pear disease in Sicily.

## Contribution

The study integrates multiple approaches to characterize the epidemic dynamics of pear decline caused by ‘Candidatus Phytoplasma pyri’.

## Key findings

- ‘Ca. P. pyri’ was detected in 69% of symptomatic plants and 4.6% of Cacopsylla pyri individuals.
- Remote sensing confirmed the epidemic spread of the disease and highlighted ongoing risks of further transmission.
- Genetic analysis showed a high similarity among phytoplasma isolates in the region.

## Abstract

Pear decline (PD), associated with ‘Candidatus Phytoplasma pyri’, is one of the most severe diseases affecting pear cultivation in Europe and the United States. Several psyllid species act as vectors of phytoplasmas belonging to the 16SrX group and play a key role in the epidemiology of the disease. This study aimed to characterize the epidemiology of pear decline in Sicily using integrated field, molecular, vector, and remote sensing approaches, four years after the first detection of PD in the region. Visual surveys and molecular analyses were conducted over two years in eight pear orchards. A total of 115 plant samples and 101 Cacopsylla spp. specimens, selected from 1435 collected individuals, were analysed, confirming the presence of ‘Ca. P. pyri’ in 69% of symptomatic plants and in 4.6% of C. pyri individuals. Genetic characterization revealed a high degree of similarity among the phytoplasma isolates analysed. Remote sensing analyses conducted since 2018, combined with vector population monitoring, confirmed the epidemic nature of PD and indicated the persistence of a risk of further pathogen spread within the region, supporting the use of remote sensing as a complementary tool for large-scale disease monitoring.