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Funded Project

Funding Program: IPM Enhancement Grants

Project Title: Sustainable Management of Bemisia tabaci biotype B on Tomato in Protected Structures

Project Director (PD): Hugh Smith [1]

Lead State: FL Lead Organization: University of Florida

Undesignated Funding: $28,417

Start Date: Mar-01-2016 End Date: Feb-28-2017

Pests Involved: Bemisia tabaci

Site/Commodity: Tomato

Area of Emphasis: IPM in protected structures

Summary: High tunnels, screen houses, greenhouses and other protected structures offer tomato growers the opportunity to produce high value specialty tomatoes, including certified organic tomatoes, with improved control over temperature and certain pests and diseases. Major pests of tomato include the sweetpotato whitefly, Bemisia tabaci, and a virus it transmits, Tomato yellow leaf curl virus (TYLCV). Many insecticides available to manage whiteflies in the field are not labeled for use in protected structures or are not compatible with commercial pollinators used in protected structures. Both conventional and organic growers of tomatoes in protected structures need sustainable methods to manage whiteflies and other pests. Sustainable approaches to whitefly management include the use of biocontrol agents such as predators and parasitoids. Dicyphus hesperus is a commercially available whitefly predator that is well-adapted to tomato, unlike most commercially-available biocontrol agents. Dicyphus hesperus has not been evaluated for management of sweetpotato whitefly or for use under Floridas hot growing conditions. Biopesticides are another component of sustainable pest management. Biopesticides include insecticidal soaps, oils and botanical and microbial insecticides. Biopesticides can help reduce whitefly numbers and in some cases transmission of virus while having limited impact on pollinators. Unlike conventional insecticides, biopesticides can be applied multiple times with limited environmental or worker safety risk, or concerns about the development of insecticide resistance. Many biopesticides are acceptable for use in certified organic production. We propose evaluating D. hesperus as a predator of sweetpotato whitefly on tomato and testing the potential to combine releases of D. hesperus with applications of biopesticides to manage whiteflies on tomato in screen houses. We will provide information on the number of predators that need to be released in response to whitefly infestations, and develop guidelines for the integration of biopesticides with predator releases to manage whiteflies and TYLCV on tomato grown in protected structures. In addition, we will carry out a statewide survey of the pest management practices and priorities of growers who produce tomato in protected structures, and offer a hands-on workshop in February 2017 to instruct growers, extension agents and other crop protection professionals in management of pests of tomato grown in protected structures. The information we generate will enable growers to protect yields and profits while reducing the use of insecticides that negatively impact pollinators and contribute to the development of insecticide resistance. There is presently very little information available for management of pests in protected structures in the southern USA. Our proposed research will provide baseline information and guidelines to growers in the rapidly expanding sector of protected agriculture. Objectives: Objective 1 Trial: Evaluation of number of whitefly eggs and immatures consumed by individual female D. hesperus. Outcome: Clients, including growers, researchers and crop protection professionals, will have information on numbers of B. tabaci immatures consumed by D. hesperus. Objective 2 Trial: evaluate contact and residual effects of five biopesticides on survival and predation by D. hesperus. Outcome: Provide baseline information on compatibility of releases of D. hesperus with applications of biopesticides for management of B. tabaci on greenhouse tomato. Objective 3 Survey of pest management practices and priorities of growers of tomato in protected structures in Florida. Outcome:Identify gaps in knowledge among tomato growers and prioritize future research and training. Objective 4 Provide workshop that offers hands-on training in management of whiteflies and other pests of greenhouse tomato using conventional insecticides, biopesticides, and biocontrol agents. Outcome: Establish meeting point and network for clients involved in production of tomato under protected structures; advance pest management expertise among clients.

Final Report:

Outputs We carried out: Three trials to evaluate predation by individual D. hesperus females on whitefly eggs One trial to evaluate predation by individual D. hesperus females on whitefly early instar nymphs. One trial evaluating predation by one, two or three mated pairs of D. hesperus adults per plant on greenhouse tomato infested with all stages of whitefly nymphs (this will be repeated this winter). Two trials screening the compatibility of D. hesperus with five key biopesticides. Two long-term evaluations of establishing D. hesperus on the banker plant mullein, one at GCREC, one at a commercial greenhouse. One presentation at the Southeastern branch meeting of the Entomological Society of America in Nashville: Pritika Pandey, Heather J. McAuslane, and Hugh A. Smith. 2017. Assessment of Dicyphus hesperus (Hemiptera: Miridae) for biological control of Bemisia tabaci (Hemiptera: Aleyrodidae) in the greenhouse. Annual Meeting of the Southeastern Branch of the Entomological Society of America. Memphis, TN. We have generated data on the number of whitefly eggs and nymphs a female D. hesperus can eat in her lifetime, as well as data on the efficacy of a range of D. hesperus densities for suppressing whitefly infestations in tomato. In addition, we have shown that some of the biopesticides used in greenhouses to suppress whiteflies are relatively compatible with releases of the predator. Together, this information will contribute to guidelines for integrated control of sweetpotato whitefly on greenhouse tomato using D. hesperus and biopesticides when necessary. Our evaluations of mullein as a banker plant for D. hesperus were not successful, possibly because the arena we used was not large enough to encourage population growth, or because we needed to provide young plants more often. We could not get D. hesperus populations to increase on mullein in greenhouses at GCREC even over a fifteen week period. Incomplete Objectives 1. I have not been able to complete a comprehensive survey of pest management practices among producers of tomato in protected structures in Florida. That effort is ongoing. 2. We have not had our workshop yet, but it is planned for Dec 2017 at GCREC. 3. We have not finalized guidelines for the use of D. hesperus in Florida greenhouses. We need to wait for the cooler weather to repeat the larger scale predation study that we carried out this past winter. Hopefully once that is completed we will have a solid data set on the number of predators to release in response to a given whitefly density.

Outcomes Egg Predation: ? Mated female Dicyphus hesperus consumed 11.12 Bemisia tabaci eggs per day and 93.43 eggs per lifetime. ? Unmated female D. hesperus consumed 10.03 B. tabaci eggs per day and 72.67 eggs per lifetime. Nymph Predation: ? Mated female D. hesperus fed on 94.4 B. tabaci nymphs per day and 857.76 nymphs per lifetime. ? Unmated female D. hesperus fed on 90.66 B. tabaci nymphs per day and 811.33 nymphs per lifetime. Longevity: ? Mated female Dicyphus hesperus live for 8.67 days when fed on eggs. ? Unmated female D. hesperus live for 7.76 days when fed on eggs. ? Mated female D. hesperus live for 12.14 days when fed on nymphs. ? Unmated female D. hesperus live for 10.64 days when fed on nymphs. Life cycle: ? Dicyphus hesperus complete their life cycle in 22.54 days on mullein plants provided with Ephestia eggs. ? Dicyphus hesperus complete their life cycle in 23.54 days on mullein plants without Ephestia eggs ? Dicyphus hesperus complete their life cycle in 24.33 days on tomato plants provided with Ephestia eggs ? Dicyphus hesperus cannot complete their life cycle on tomato plants without Ephestia eggs ? The biopesticides azadirachtin), insecticidal soap, Paecilomyces fumosoroseus, and stylet oil caused mortality in D. hesperus that was not statistically different from the untreated control in a laboratory study. Additional information is needed to determine the compatibility of applications of Beauvaria bassiana with releases of D. hesperus in the greenhouse environment. ? In a greenhouse study, three consecutive weekly releases of 12 D. hesperus adults per infested tomato plant resulted in an 8-fold reduction in immature whitefly stages (egg and nymph) relative to the untreated control two weeks after the third release.

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