D3517: Viruses interaction in a common vector: Antagonistic effects and competitive dynamics between two tomato-infecting begomoviruses in Bemisia tabaci

Polyphagous insect vectors have the potential to acquire multiple viruses from various virus-infected plants, and the interaction between these viruses within an insect vector may contribute to a shift in disease epidemics. In this study, we investigated the interaction between two tomato-infecting begomoviruses, tomato yellow leaf curl Thailand virus (TYLCTHV) and tomato leaf curl Taiwan virus (ToLCTV), in their common vector, Bemisia tabaci. A series of experiments were conducted to study whether the acquisition of one virus affects the acquisition, infection, and transmission of the other. The results indicated that when whiteflies first acquired TYLCTHV and then ToLCTV, the titers of ToLCTV in the midgut, hemolymph, and primary salivary glands of whiteflies were significantly lower compared to whiteflies that acquired ToLCTV only. However, the titer of ToLCTV in the organs and hemolymph of whiteflies were not different between the whiteflies acquired ToLCTV first and TYLCTHV later and the whiteflies acquired ToLCTV only. In contrast, the titers of TYLCTHV in the organs and hemolymph of whiteflies were not changed no matter ToLCTV was acquired earlier or later than TYLCTHV. Whitefly transmission assays found that the infection rate of TYLCTHV were higher than that of ToLCTV no matter that the whiteflies acquired these viruses first or later. In summary, TYLCTHV exhibited an antagonistic effect on the infection of ToLCTV in B. tabaci, and TYLCTHV demonstrated higher competitiveness than ToLCTV on whitefly transmission. This study contributes a new perspective to comprehend the impact of virus-vector interaction on the epidemiology of plant viruses.