Tomato spotted wilt orthotospovirus

Tomato Spotted Wilt Orthotospovirus (TSWV) is a plant pathogenic virus that belongs to the genus Orthotospovirus within the family Tospoviridae. It is known for causing the disease tomato spotted wilt in a wide range of host plants, affecting both agricultural crops and ornamental plants worldwide. TSWV is notable for its broad host range, infecting over 1,000 plant species across more than 80 families, including important crops such as tomato, pepper, lettuce, peanut, and tobacco. The virus is transmitted by thrips, small insects that feed on the sap of plants, making management and control of the disease challenging.

Symptoms

The symptoms of tomato spotted wilt vary widely depending on the host plant, the age of the plant at the time of infection, and environmental conditions. Common symptoms include:

• Bronzing of leaves
• Ring spots and line patterns on leaves and fruits
• Wilting and stunting of plants
• Necrosis or death of tissue, particularly in the shoot tips

Transmission

TSWV is primarily transmitted by thrips, specifically the western flower thrips (Frankliniella occidentalis) and the tobacco thrips (Frankliniella fusca). These insects acquire the virus while feeding on an infected plant during their larval stage and can transmit the virus throughout their adult life. Transmission occurs when the thrips feed on the sap of a healthy plant, introducing the virus into the plant's cells.

Management

Management of tomato spotted wilt focuses on controlling the thrip population and preventing the spread of the virus. Strategies include:

• Cultural control methods such as removing infected plants and weeds that can serve as reservoirs for the virus.
• Using reflective mulches to deter thrips from landing on plants.
• Applying insecticides to control thrip populations, although resistance can be a problem.
• Growing resistant plant varieties where available.

Economic Impact

The economic impact of TSWV is significant, particularly in the production of susceptible crops such as tomatoes, peppers, and peanuts. Yield losses and the cost of management strategies can be substantial, affecting both large-scale agricultural operations and smallholder farmers.

Research

Research on TSWV focuses on understanding the virus's biology, transmission mechanisms, and interactions with host plants and vectors. Efforts are also directed towards breeding resistant plant varieties and developing more effective and sustainable management strategies.