Incorporating Natural, Non-toxic Arthropod Resistant Tomato Varieties into Southern Production Systems

View the project final report

Commodities

• Vegetables: tomatoes

Practices

• Crop Production: crop improvement and selection, plant breeding and genetics, varieties and cultivars
• Education and Training: demonstration, extension, participatory research
• Pest Management: biological control

Arthropod pests critically limit yields and quality of tomatoes in the Southeast. Whiteflies and thrips transmit viruses that can result in 100 percent crop loss. Additionally, whiteflies, thrips and spider mites reduce yield through foliar feeding, and spider mites and thrips cause fruit scarring. The management of these major pests and the viral diseases they vector to tomatoes relies heavily on pesticides. But tomato producers are caught in a classic "pesticide treadmill" -- using frequent pesticide applications that increase the risks of resistance development (due to pests' rapid life cycles) and cause secondary pest outbreaks (due to the pesticides' non-target effects on natural enemies), which necessitate further pesticide applications. Therefore, the introduction of new, pest-repellent tomato lines and hybrids can break this cycle at its roots by reducing pest abundance (through repellency to pests) and solving the shortcomings of existing TSWV-resistant lines (which are not arthropod resistant and can still suffer feeding damage).

Such new pest-repellent tomato lines and hybrids, which incorporate natural non-toxic insect resistance from wild tomato, are available from Cornell University tomato breeding program. The leaves and stems of the new lines have trichomes that produce acylsugars, which are highly repellent to many pest species (including thrips and whiteflies) and reduce pest feeding, oviposition, and virus prevalence. But new lines require field testing to integrate into current production practices. Therefore, the proposed project will assess a selection of four experimental thrips-and whitefly-resistant tomato lines and hybrids (varying in acylsugar type and level) for resistance to spider mites, and compatibility with natural enemies of these major pests in the tomato production systems of the Southeast.

We will determine in laboratory studies if select experimental acylsugar lines/hybrids known to control whiteflies and thrips also control twospotted spider mites, which have not yet been directly verified. We will also evaluate non-target effects of these lines on selected natural enemies to confirm that acylsugar-mediated insect resistance can be integrated with biological control. We will measure the effects of acylsugars on pest and natural enemy abundance and virus prevalence in commercial fields in GA and SC. We will consult with our collaborating growers and field test the tomatoes lines in their farms, scale and small, and spring and fall production. We have planned for a variety of outreach activities to engage our stakeholders directly.

A summary of project results prepared for seed companies will encourage mass production of seeds, and will be posted on the Cooperative Extension websites of Clemson University and the University of Georgia. In addition, project updates will occur at vegetable grower meetings, and demonstrations are planned to coincide with the annual Vegetable Field Days in GA and SC. Finally, we will organize workshops on natural plant traits for agriculture for improved pest management at the Southeast Vegetable and Fruit Expo and Southeast Regional Fruit and Vegetable Conference. Therefore, our coordinated research and outreach efforts will help break the "pesticide treadmill" currently challenging sustainable production of tomatoes.

• Determine if acylsugar producing tomato lines provide sufficient resistance to twospotted spider mites and select the most spider mite-resistant line.
• Determine the compatibility of acylsugar producing lines with biological control of thrips and whiteflies by four known biological control agents.
• Determine the compatibility of acylsugar producing lines with biological control of spider mites by three predatory mites.
• Examine impacts of acylsugar producing lines on pest and natural enemy abundance, and virus incidence in southern commercial tomato fields.