Dealing with complex virus disease problems a case of Tospovirus Diseases in Vegetables Naidu A. Rayapati Department of Plant Pathology Washington State University Irrigated Agriculture Research & Extension Center Prosser, WA 99350, USA [email protected]
Group of emerging plant viruses causing economically significant damage to a broad range of field crops, vegetables, ornamentals, fruits, etc. Viruses can not move by themselves and they need a “safe” vehicle to spread from plant to plant one such is thrips -Naidu A. Rayapati, Presentation at CPMB, TNAU 19th,August 2009
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Dealing with complex virus disease problems
a case of Tospovirus Diseases in Vegetables
Naidu A. RayapatiDepartment of Plant PathologyWashington State UniversityIrrigated Agriculture Research & Extension CenterProsser, WA 99350, [email protected]
An overview
Thrips vectors
Tospoviruses
Topics
Thrips : Greek word for “wood worms”
Thrips : a plural noun
Each individual is “a thrips” like the word “sheep”
Thrips: What are they?
What are Tospoviruses ?
Type member: Tomato spotted wilt virus
Group of emerging plant viruses causing economically significant damage to a broad range of field crops, vegetables, ornamentals, fruits, etc.
Thrips play a vital role in the spread of tospoviruses
Tospovirus
Thrips Host
The virus disease triangle
• Viruses can not move by themselves
• They need a “safe” vehicle to spread from plant to plant• Thrips control strategies may be a better option to disrupt the disease triangle
Thrips as vectors of viruses
• As vectors directly transmitting virusese.g. Tospoviruses in vegetables, field crops
and ornamentals
• As carriers of pollen containing virusese.g. certain other viruses (Tobacco streak virus)
General features of thrips• Small size
- difficult to detect • Polyphagous
- feed on a broad range of plant species
- feed on different parts of the plant (pollen, flower structures, leaves, stems)
• Show habitat infidelity- extraordinary ability to adapt- can expand geographic range- can spread to new crops
• Have superior reproductive output - produce many off springs
• Have propensity to ‘overwinter’ on a broad range of plant species - survive through out the year
Western flower thrips (WFT)(Frankliniella occidentalis)
Melon thrips (Thrips palmi)
Source: www.eppo.org
• A native to the southwestern USA• Spread through global trade
in ornamental greenhouse plants around the world from mid-1980s
• A native to Southeast Asia• Expanded its geographic
range in 1970s and 80s
Geographic expansion of thrips vectors
• virus vectors introduced in to new areas
• viruses introduced in to new areas by land, sea and air, via
international trade or accidentally
Viruses and insects do not carry passports
The planetary ecosystem has changed !!!
Global village
Challenges in controlling tospovirus diseases
Tospoviruses
• broad host range• multiple vector species• evolution of new strains• ability to overcomehost plant resistance
Vector thrips
• polyphagous & show habitat infidelity• has superior reproductive output• has propensity to ‘overwinter’ on a
broad range of plant species• develop resistance against pesticides
Challenges in controlling tospovirus diseases
Host plant resistance
Resistance only against TSWV
• Sw-5 resistance gene in tomato against TSWV• Tsw resistance gene in Capsicum against TSWV
Challenges in controlling tospovirus diseases
Host plant resistance
• No broad-spectrum resistancee.g. CaCV overcame the Sw-5 resistance gene in tomatoe.g CaCV overcame TSWV resistance in
Capsicum chinense accessions PI 152225, PI 159236 and AVRDC 00943
• Resistance to ‘Asian’ tospoviruses not yet knowne.g. is there resistance to PBNV in tomato ?
Challenges in controlling tospovirus diseases
Challenges in controlling tospovirus diseases
Host plant resistance
• virus-specific• no ‘one-size-fits all’ approach
Durable resistance is difficult to achieve
due to rapid evolution of resistance-breaking virus strains
K.S. Ravi, Mahyco, India
biologic chess game !!!
Crop Improvement against tospoviruses
Management of tospovirus diseases:
an IPM approach• Knowledge about the virus & vector• Diagnostic tools• Ecology and epidemiology• Thrips vector management options• Altering cropping patterns• Deploying tolerant/resistant cultivars• Capacity building
Integrated Management of Thrips-borne Tospoviruses in Vegetable Cropping Systems
in South Asia and Southeast Asia Region
Funded by Integrated Pest Management Collaborative Research
Support Program (IPM CRSP) of USAID
Global IPM Theme: Insect-transmitted viruses
“minimize crop losses due to thrips-borne tospoviruses in smallholder vegetable farming systems in South and Southeast Asia through new science and technologies and multidisciplinary global partnerships,and improve nutritional status of people including women and children”
Project Goal
1. Conduct strategic research on tospoviruses and thrips vectors
2. Carryout applied and adaptive research to deploy ‘eco-friendly’ IPM strategies to control tospovirus diseases
3. Strengthening institutional capacities within host countries to conduct problem-oriented research on virus diseases