emerging issues in the management of silverleaf whitefly
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Emerging Issues in the Management of Silverleaf Whitefly
Hugh SmithVegetable Entomologist
Gulf Coast Research and Education CenterBalm, FL 33598
Whitefly Biotypes in Florida
Biotype Q: First detected in Florida 2005.Why are we concerned?
Biotype A: Up until late 1980s. Rarely caused damage.
Biotype B (silverleaf whitefly): Since late 1980s.TYLCV and irregular ripening.
I. Generalizations about the Q biotype
“Q biotype is resistant to neonicotinoids (MoA 4A).”
China, Israel, Spain:
Resistant to –imidacloprid (Admire)thiamethoxam (Platinum, Actara)acetamiprid (Assail)
However:
Insecticides with efficacy on Q (adults and nymphs):
● Venom/Scorpion (dinotefuran; MoA 4A)
● Sivanto (flupyradifurone; MoA 4D)
● Verimark/Exirel (cyazypyr; MoA 28)
II. Generalizations about the Q biotype
“Q biotype is resistant to insect growth regulators (IGRs)”
IGRs: prevent nymphs from becoming adults.
Israeli cotton: Q was resistant to pyriproxifen(Knack).
● China: Q not resistant to pyriproxifen
IGRs used in Florida tomato:
● Knack (pyriproxifen) – MoA 7C● Courier (buprofezin) – MoA 16
Courier (buprofezin)MoA 16
● reduces egg viability.
● interferes with molting.
● contact only.
● 2 applications at least 5 d apart.
● 1 day PHI.
Knack (pyriproxifen)MoA 7C
● reduces egg viability
● interferes with molting , adult emergence.
● translaminar: will reach underside of leaf.
● 2 applications at least 2wk apart.
● 1 day PHI
Other insecticides for controlling whitefly nymphs:
Movento (spirotetramat)
Oberon (spiromesifen)
● Lipid biosynthesis inhibitors
● Both are MoA 23 so choose one or the other.
● Movento works well on Q elsewhere.Ambimotile.
Biotype Q in Florida● April 2016: Q detected on hibiscus plants in residential landscape in Palm Beach County.
● First time Q has been detected in the landscape vs on potted plant in box store.
● Multiple detections in multiple counties since then.
● Glades Crop Care has been submitting samples from field vegetables since April: all have been B biotype.
● So far no evidence that Q has become established in field horticulture.
Current opinion: Whitefly biotypes are different species.
How much can we generalize about how an entire species reacts to insecticides?
Insecticide resistance: ● inherited (genetic)● determined by insecticide pressure● varies among populations of the same species.
Resistance Monitoring Biotype B: Oct 2013-Feb 2015.
● Whiteflies tested from 19 sites - Balm to Homestead.
● Susceptibility to Admire, Platinum, Venom and Sivanto.
● LC50 = “50% Kill” of test whiteflies. How much is needed to kill 50% of whiteflies from a given crop.
● The lower the LC50, the more effective the insecticide (less material needed to kill 50%).
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(ppm
)SIVANTO PRIME (flupyradifurone)
Sivanto
50 x Lab LC50 Sivanto
0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.51.61.71.81.92.02.12.22.32.42.52.62.72.82.93.03.13.23.33.43.53.6
LC50
(ppm
)
Sivanto
Venom
VENOM (dinotefuran)
0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.51.61.71.81.92.02.12.22.32.42.52.62.72.82.93.03.13.23.33.43.53.6
LC50
(ppm
)
Sivanto
Venom
VENOM (dinotefuran)
0.01.02.03.04.05.06.07.08.09.0
10.011.012.013.014.015.016.017.018.019.020.021.022.023.024.025.026.027.0
LC50
(ppm
)
Admire
Sivanto
Venom
ADMIRE (imidacloprid)
0.01.02.03.04.05.06.07.08.09.0
10.011.012.013.014.015.016.017.018.019.020.021.022.023.024.025.026.0
LC50
(ppm
)
Platinum
Sivanto
Venom
PLATINUM (thiamethoxam)
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Admire
Platinum
Sivanto
Venom
Resistance Monitoring: Silverleaf Whitefly Biotype B in Florida
● Some populations generally susceptible to all four materials.
● Some populations generally tolerant to all four materials, including Sivanto, even though they had never been exposed to it.
● On the whole, populations responded in a similar way to Admire and Platinum, and in a similar way to Sivanto and Venom.
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LC50
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Admire
Platinum
Sivanto
Venom
Smith, H. A., C. A. Nagle, C. M. MacVean, C. L. McKenzie. Susceptibility of Bemisia tabaci MEAM 1 (Hemiptera: Aleyrodidae) to imidacloprid, thiamethoxam, dinotefuran and flupyradifurone in South
Florida. Insects. In Revision.
● It is not possible to generalize about biotype B susceptibility to insecticides.
● The biotype Q populations in Florida are the result of multiple introductions from multiple sites.
● It is unlikely that we can accurately generalize about the impact Q will have on the state or how Q will respond to insecticide treatments without data.
III. Generalizations about the Q biotype“Biotype Q remains permanently resistant to insecticides.”
● This is biologically impossible.
Bioassay set-up: neonicotinoid tolerance
● How many generations does it take for susceptibility to return?
0
10
20
30
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Hillsborough1Admire
Hillsborough1Platinum
Hendry1Admire
Hendry1Platinum
LC50
ppm 2nd-3rd gen
6th-7th gen9th-10th gen
Biotype BTesting susceptibility to Admire and Platinum over multiple generations without exposure.
Funding from FDACS
Assessing the biotype Q threat to Florida agriculture.
1. Survey for biotype.
2. Test for tolerance.
1. Survey for biotype.
● Submit whitefly adults from your fields to Smith lab.
● Use my Fedex/UPS number.
● I will send to Cindy McKenzie for biotyping.
2. Test for tolerance● Establish colonies of Q at GCREC.
● Test for susceptibility to key insecticides.
● Develop guidelines for management.
Secure containment facility at GCREC for biotype Q resistance monitoring.
AcknowledgementsFunding
Florida Tomato CommitteeFlorida Department of Agriculture and Consumer ServicesBayer Crop Science.
Smith LabCurtis Nagle, Laurie Chambers, Justin Carter, Marc Santos, Pritika Pandey, Karla Medina-Ortega
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