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Poster: Epidemiology: Pathogen-Vector Interations


Transmission of a 16SrIII-L phytoplasma by leafhoppers (Scaphytopius marginelineatus) to cassava (Manihot esculenta Crantz) in Colombia
E. ALVAREZ (1), C. BETANCOURTH (1) (1) CIAT, Colombia

As much as 30% of cassava production in Colombia, is affected by cassava frogskin disease (CFSD). The disease is associated with a 16SrIII-L phytoplasma that is transmitted between plants through vegetative propagation or by sap-sucking insect vectors. We collected 250 insect samples in Palmira and Santander de Quilichao; analyzed them for the presence of phytoplasmas during 2009 and 2012–2014; and detected a 16SrIII-L phytoplasma. Greenhouse experiments with symptomatic plants showed that potential insect vectors for cassava were hemipterans, particularly the Cicadellidae and Cixiidae families, and include the cicadellid leafhopper Scaphytopius marginelineatus. Colonies of this leafhopper were mass-reared on cassava (‘SM 909-25’) and bean (‘ICA Pijao’) plants. To determine the acquisition period, 50 individual insects were selected and exposed to phytoplasma-infected cassava plants for 2, 4, 6, and 8 days. The insects then underwent an additional 2 weeks’ incubation period, after which surviving insects were allowed to infest healthy cassava plants over a 5-to-7-day inoculation period. Molecular studies of plant tissues, based on PCR amplification and DNA sequencing, confirmed both the acquisition (6 days after inoculation) and transmission (3 weeks) of a phytoplasma. Sequences KP75989, and KP759898-KP759902 were reported to GenBank. Previous studies indicated that potential infestations of cassava crops by leafhoppers can be controlled by organic neem oil spray