D3476: Establishing a model system to study insect vectors of Candidatus Phytoplasma in Costa Rica

Species of planthoppers (Cicadellidae: Hemiptera) are vectors of bacteria strictly restricted to plants’ sieve tubes such as Candidatus Phytoplasma. In Costa Rica, phytoplasmas have been reported in Sechium edule, Saccharum officinarum, Glycine max among other hosts. Recently a phytoplasma of 16Sr VII group (a ‘Candidatus Phytoplasma fraxini’ related strain) was detected in Trichilia havanensis Jacq. (Meliaceae) (locally known as “Uruca”). The Uruca tree can serve as a reservoir of ‘Ca. Phytoplasma’ and due to its wide distribution across Costa Rica central valley it represents a model system to study phytoplasma transmission and disease epidemiology. This study aims to identify morphologically and molecularly vectors of ‘Ca. Phytoplasma’ in Uruca trees from urban and agricultural systems. Cicadellids were collected from four sample sites, they were classified into morphospecies based on morphological characteristics. Insects were pinned to keep them as vouchers and the second pair of legs was dissected from each specimen to perform DNA extraction. The partial COX1 gen was used for sequencing. A total of 121 morphospecies have been registered. Additionally, ecological indexes were calculated for the sampling sites, ranging between 9.8 to 16.5 for Shannon-Wiener´s diversity index and 27 to 40 for species richness. Several genera have been identified by morphological and molecular techniques, including Scaphytopius, Gyponana, Osbornellus, Agallia and Tylozygus. ‘Candidatus Phytoplasma’ was detected by nested PCR in the genus Scaphytopius and Osbornellus. Preliminary results suggest two species of cicadellids as phytoplasma vectors in Uruca, moreover we are registering a high diversity of cicadellids in urban and semiurban sits.