Transmission of areca palm velarivirus 1 (APV1) by mealybugs causes yellow leaf disease (YLD) in betel palm (Areca catechu)

Yellow leaf disease (YLD) is the most destructive disease of betel palm (Areca catechu). A strong association between YLD and areca palm velarivirus 1 (APV1) has been observed. However, the causal relationship between APV1 and disease, and the transmission mode, require further investigation. This work showed that APV1 was transmitted by both Ferrisia virgata and Pseudococcus cryptus mealybugs, and caused YLD symptoms in betel palm seedlings; therefore, we demonstrate that APV1 is a causal agent of YLD. APV1 was detected in the stylets, foreguts, midguts, and hindguts of the vectors via both immunocapture RT-PCR and immunofluorescence assays. APV1 was not transmitted transovarially from viruliferous female F. virgata to their progeny. In summary, the transmission of APV1 by F. virgata may occur in a non-circulative, semi-persistent manner. This study fills important gaps in our knowledge of velarivirus transmission, which is critical for developing YLD management practices.