Evaluation of thrips-mediated Tomato spotted wilt virus transmission to screen TSWV-resistant peanut genotypes

Tomato spotted wilt virus (TSWV) is transmitted by thrips in a persistent manner. Wide host range of TSWV and thrips has severely constrained TSWV management. Planting of resistant cultivars is the most reliable and widely adopted management tactic. Resistant cultivars are obtained through conventional breeding. Screening for thrips and TSWV is usually conducted under field conditions. However, field screening is limited by inconsistent TSWV and thrips pressure, time, and costs. Our objective is to develop an optimal thrips-mediated transmission protocol under greenhouse conditions to assist in screening peanut genotypes. Tobacco thrips, Frankliniella fusca (Thysanoptera: Thripidae), were used for all experiments. Viruliferous and non-viruliferous thrips were maintained on TSWV-infected and healthy peanut foliage respectively. Two tobacco thrips life stages (nymphs and adults), four densities (1, 3, 5, and 10), and four inoculation access periods (0.25h, 1h, 24h, and 96 h) were evaluated for TSWV transmission efficiency. At least 20 seedlings in two replications were used for each life stage, density, and inoculation access period. Upon inoculation, the plants were sprayed with a thripicide and caged in thrips-proof cages. TSWV-infection in inoculated plants was tested by double antibody sandwich enzyme-linked immunosorbent assay 3 weeks post inoculation. TSWV transmission efficiency was affected by thrips density and duration of inoculation access period. Transmission rates ranged from 0-70%. Both nymphs and adult thrips transmitted TSWV efficiently. Further, results of ongoing experiments to correlate TSWV-infection rates in individual thrips to TSWV transmission efficiency in peanut seedlings will also be presented.