Impatiens necrotic spot orthotospovirus

Impatiens Necrotic Spot Orthotospovirus (INSV) is a plant pathogen that causes significant economic losses in a wide range of ornamental and vegetable crops. It is a member of the genus Orthotospovirus, within the family Tospoviridae. INSV is closely related to Tomato spotted wilt virus (TSWV) and shares many of the same hosts and symptoms. The virus is known for causing necrotic spots on leaves, stems, and flowers, leading to reduced plant vigor and, in severe cases, plant death.

Overview

INSV has a broad host range, affecting over 600 plant species across various families. It is particularly detrimental to ornamental plants such as Impatiens, Begonia, and Chrysanthemum, as well as vegetables including Lettuce, Tomato, and Pepper. The virus is transmitted by thrips, specifically the western flower thrips (Frankliniella occidentalis), which acquire the virus while feeding on infected plant tissue. Once acquired, the virus can be transmitted throughout the thrips' life.

Symptoms

The symptoms of INSV infection can vary widely depending on the plant species, age of the plant, and environmental conditions. Common symptoms include:

• Necrotic spots and rings on leaves and flowers
• Stunting and distortion of new growth
• Yellowing and wilting of leaves
• Stem necrosis
• Reduced yield in vegetable crops

Transmission

INSV is primarily transmitted by the western flower thrips, Frankliniella occidentalis. Thrips acquire the virus by feeding on infected plant tissue during their larval stage. Once acquired, the virus is retained through the thrips' development into adulthood, allowing them to infect new plants. The virus is not transmitted through seeds or mechanically by tools or hands.

Management

Management of INSV involves an integrated approach combining cultural, biological, and chemical strategies:

• Cultural control: Includes practices such as removing infected plants, managing weeds that can serve as virus reservoirs, and using reflective mulches to deter thrips.
• Biological control: Utilizes natural enemies of thrips, such as predatory mites and parasitic wasps, to reduce thrips populations.
• Chemical control: Involves the application of insecticides to control thrips populations. However, resistance to insecticides is a growing concern, and chemical control should be used judiciously as part of an integrated pest management (IPM) strategy.

Prevention

Preventive measures are crucial in managing INSV. These include:

• Monitoring for thrips and early detection of the virus through regular scouting and the use of sticky traps.
• Implementing strict sanitation practices to remove plant debris and eliminate potential virus reservoirs.
• Using virus-free plant material and resistant plant varieties when available.

Conclusion

Impatiens Necrotic Spot Orthotospovirus is a challenging pathogen due to its wide host range, persistent transmission by thrips, and the significant impact on ornamental and vegetable crops. Effective management requires an integrated approach that combines cultural, biological, and chemical strategies, along with vigilant monitoring and preventive measures.