Ferrisia gilli (Hemiptera: Pseudococcidae) Transmits Grapevine Leafroll-Associated Viruses

Area of Science:

• Plant Pathology
• Entomology
• Viticulture

Background:

• Grapevine leafroll disease, caused by grapevine leafroll-associated viruses (GLRaV), is a major economic threat to grape production globally.
• Several mealybug species are known vectors of GLRaV, facilitating disease spread.
• Ferrisia gilli Gullan is identified as a new mealybug pest impacting grapevines in California's Sierra Foothill region.

Purpose of the Study:

• To investigate the potential of the newly identified mealybug pest, Ferrisia gilli, as a vector for grapevine leafroll-associated viruses (GLRaV).
• To determine which specific GLRaV species Ferrisia gilli can acquire and transmit to healthy grapevines.

Main Methods:

• Controlled virus acquisition experiments were performed using grapevine source accessions infected with GLRaV species 1, 2, 3, and 4LV.
• Transmission experiments were conducted by exposing uninfected recipient vines to mealybugs that had acquired viruses from infected sources.
• Virus presence in acquired and transmitted samples was confirmed using molecular detection methods.

Main Results:

• Ferrisia gilli successfully acquired GLRaV species 1, 2, 3, and 4LV from infected grapevines.
• The mealybug demonstrated the ability to transmit GLRaV-3 and GLRaV-4LV to healthy, uninfected recipient vines.
• Acquisition of GLRaV-1 and GLRaV-2 was confirmed, but transmission of these specific species was not determined in this study.

Conclusions:

• Ferrisia gilli is confirmed as a vector for GLRaV-3 and GLRaV-4LV, adding to the list of mealybug species that transmit grapevine leafroll disease.
• The presence and vectoring capability of F. gilli represent a new threat to the grape industry in California and potentially other wine-growing regions.
• Integrated pest management strategies should consider F. gilli's role in the epidemiology of grapevine leafroll disease.