Vinicius Henrique Bello - Universidade Estadual Paulista Julio de Mesquita Filho, 28108, Plant Portection, Jose Barbosa de Barros, 3780, Botucatu, Sao Paulo, Brazil, 18610-034; UNESP;  
Saptarshi Ghosh - Agricultural Research Organization Volcani Center, 42718, Entomology, Rishon LeZion, Israel;
 Renate Krause-Sakate - Universidade Estadual Paulista Julio de Mesquita Filho, 28108, Plant Portection, Botucatu, São Paulo, Brazil;  
Murad Ghanim - Agricultural Research Organization Volcani Center Information Center, 530612, Entomology , Rishon LeZion, Israel;

Pepper cultivation in Israel has recently been constrained by two sympatric poleroviruses, Pepper vein yellows virus-2 (PeVYV-2) and Pepper whitefly-borne vein yellows virus (PeWBVYV) which are transmitted specifically by aphids and whiteflies, respectively. The interaction between PeVYV-2 and PeWBVYV inside the host plant and the insect vectors were investigated in this study. Our results show that PeVYV-2 and PeWBVYV compete against each other inside the host plant and also inside aphids. PeWBVYV was the weaker competitor inside the host plant with diminished transmission rates when inoculated simultaneously or successively after PeVYV-2 and could only be transmitted efficiently when inoculated first and then challenged by PeVYV-2. Successive inoculations of plants with viruliferous whiteflies with PeWBVYV, followed by viruliferous aphids with PeVYV-2 led to co-infection rate of 60%, however with severely reduced titers of PeWBVYV in the co-infected plants compared to singly infected ones. In contrast, PeVYV-2 was the weaker competitor inside the insect vector with reduced quantities of the acquired virus and reduced transmission rate by aphids when given prior acquisition on PeWBVYV. However, we also show that transmission efficiency of PeVYV-2 and PeWBVYV from co-infected plants by whiteflies and aphids remain comparable to that from singly-infected plants. This is probably due to the reduced titers of PeWBVYV inside co-infected plants causing lesser impact on transmission of PeVYV-2 by aphids and the stronger competitiveness of PeWBVYV inside whitefly. Competitive interactions between PeVYV-2 and PeWBVYV inside the host plant and insect vector can thus be beneficial for their co-existence.