Which type of diseases are often spread by aphids or leafhoppers?

Viral diseases are often spread by aphids or leafhoppers due to the feeding behavior of these pests. When aphids or leafhoppers feed on the sap of a plant, they can acquire plant viruses from infected plants. Once these insects become contaminated, they can transfer the viruses to healthy plants during subsequent feedings. This process is known as "vector transmission", where insects act as vehicles to introduce viral pathogens.

Unlike fungal or bacterial diseases that are typically spread through spores or direct contact, viral diseases require a living vector for transmission. Nutritional disorders relate more to deficiencies or toxicities in the environment rather than pathogen spread. Understanding these mechanisms is essential for managing and preventing viral diseases in crops, emphasizing the importance of monitoring and controlling aphid and leafhopper populations to reduce the risk of disease outbreaks.