1. Carlos J. Esquivel, PhD student
Length of thiamethoxam seed treatment activity against soybean aphid (Aphis glycines)
Carlos J. Esquivel,
PhD student
09/27/16

2. Soybean aphid life cycle
Biotype 1
Biotype 4
It has two common hosts (primary is buckthorn, and secondary is soybean)
It can be winged and wingless (main phenotype during summer)
For this talk I’m going to concentrate on the aptera soybean with parthenogenic reproduction on soybean
(by Hammond, Michel, and Eisley, Department of Entomology,
The Ohio State University)
Ragsdale et al., 2004

3. Distribution Invasive species (from eastern Asia)
Rapid expansion in a period of ~3 years

4. Damage by soybean aphid
Reduce plant growth, pod number, seed number, seed weight, seed oil concentration (Beckendorf et al., 2008)
Promote of sooty mold growth (Tilmon et al., 2011)
Virus vector of soybean mosaic virus (Hill et al., 2001)
46% yield reduction (McCarville et al., 2011
~47 bushels/acre (average US soybean yield)
21.2 bushels/acre = $201/acre
SBA could can have devastating effects on soybean production
Hill et al., 2001: First Report of Transmission of Soybean mosaic virus and Alfalfa mosaic virus by Aphis glycines in the New World
McCarville et al., 2007: current soybean price $350/MT or $9.5/bushel

5. Chemical control of soybean aphid
Foliar applications with pyrethroids (Ragsdale et al., 2007)
Seed treatment is fairly used at present (Hodgson et al., 2012)
Thiamethoxam
Thiamethoxam used as seed-treatment is expanding
g a.i. /ha
Modified from Bahlai et al., 2015

6. Thiamethoxam seed-coating reports
Aphid control is lost at 42 DAP (McCarville and O’Neal, 2013)
Insect control persists until 49 DAP (McCornack and Ragsdale, 2006)
Reduced controlled at 28 DAP (EPA, 2014)
Insecticide loses effectivity during later aphid infestations (Kandel et al., 2015)
No aphid control perceived during soybean season (Johnson et al., 2008)
Aphid control by seed-treatment is limited to early stages of the crop
McCaville and O’Neal 2013: Iowa.
McCornack and Ragsdale 2006: Minnesota.
Johnson et al 2008: Iowa.
Contrast
Magalhaes et al 2009: Nebraska. (they saied: Seed treatment maintain aphid population under the economic threshold along the growing season (Magalhaes et al., 2009))

7. Aphid control
Insecticide concentration and aphid control decrease over time
READ: The effectiveness of neonicotinoid seed treatment in soybean
Soybean aphid out- breaks typically occur in late July and August for this region (Ragsdale et al. 2011).
prairiecalifornia.com

8. Insecticidal effect on soybean aphids through the time is still unclear
Aphid control
Insecticide concentration and aphid control decrease over time
READ: The effectiveness of neonicotinoid seed treatment in soybean
Soybean aphid out- breaks typically occur in late July and August for this region (Ragsdale et al. 2011).
prairiecalifornia.com

9. Questions:
What is the survival of aphids when feed on soybean plants obtained from thiamethoxam-coated seeds?
How long does the insecticidal effect of seed-coating last in soybean plants?
Objective:
Evaluate aphid survival when feed on soybean plants obtained from insecticide-treated seeds

10. Experimental design Factorial Randomized Complete Block design
Factors:
Aphid biotype: Biotype 1, and Biotype 4
Seed treatment: Seed coated, and uncoated seed
Days after planting for infestation : 7, 14, 21, 28, 35, and 42

11. Materials
Seed coated: Cruiser Maxx® soybean (Syngenta, Greensboro, NC)
Uncoated seed: insecticide coating removed
Infest the newest fully mature leaflet
Aphid survival recorded 24 h
after infestation
Greenhouse conditions
16 h light/day; 25˚C; ~75% RH

12. Results

13. What is the survival of aphids when feed on soybean plants obtained from thiamethoxam-coated seeds?

14. Aphid survival A B * z * * NS * * NS NS * * * *
Biotype 1
Biotype 4

15. Aphid survival B A * * * * * * * * * NS NS NS 15% 35% 90% 13% 55% 92%z * * NS NS NS * * * * * *
15%
35%
90%
13%
55%
92%

16. How long does the insecticidal effect of seed-coating last in soybean plants?

17. Aphid survival A B * z * * NS * * NS NS * * * *
Biotype 1
Biotype 4

18. Aphid survival * B A * * * * * * * * * NS NS NS Biotype 1 Biotype 4
= P-value ≤0.05; NS = no significant *

19. Aphid survival * B A 42 DAP 35 DAP * * * * * * * * * NS NS NS
Insecticidal control last up to 35 DAP
Biotype 1
Biotype 4
= P-value ≤0.05; NS = no significant; DAP = days after planting *

20. Conclusions
Aphid survival on young plants (14 days old or younger) is limited (<15%), but on plants older than 42 days is less restricted (>90%)
Under greenhouse conditions, the insecticidal effect from seed coating last up to 35 DAP

21. Significance
Even under controlled conditions, seed treatment has a short period controlling aphids

22. Significance
Even under controlled conditions, seed treatment has a short period controlling aphids

23. Significance
~30 DAP, more than >50% of aphid population feeding on treated plants survive
-Potential threat to predatory natural enemies
By Marlin Rice
By Fred Hoffman
By University of Florida
Douglas,
Rohr, and
Tooker, 2015
By Emily Fox
By Tom Murray

24. Future work Measure insecticide concentration in plant tissues
Confirm insecticide accumulation in aphids survivors
Evaluate fitness of predatory natural enemies when prey on aphids with accumulation of insecticide

25. References
Alleman, R. J., Grau, C., & Hogg, D. . (2002). Soybean aphid host range and virus transmission efficiency.
Bahlai, C. A., Werf, W. Vander, O’Neal, M., Hemerik, L., & Landis, D. A. (2015). Shifts in dynamic regime of an invasive lady beetle are linked to the invasion and insecticidal management of its prey.
Beckendorf, E. A., Catangui, M. A., & Riedell, W. E. (2008). Soybean Aphid Feeding Injury and Soybean Yield, Yield Components, and Seed Composition.
Douglas, M. R., Rohr, J. R., & Tooker, J. F. (2014). Neonicotinoid insecticide travels through a soil food chain, disrupting biological control of non-target pests and decreasing soya bean yield.
Casida, J. E., & Durkin, K. A. (2013). Neuroactive Insecticides: Targets, Selectivity, Resistance, and Secondary Effects.
Hill, J. H., Alleman, R., Hogg, D. B., & Grau, C. R. (2001). First Report of Transmission of Soybean mosaic virus and Alfalfa mosaic virus by Aphis glycines in the New World.
Hodgson, E. W., Kemis, M., & Geisinger, B. (2012). Assessment of Iowa soybean growers for insect pest management practices.
Jeschke, P., & Nauen, R. (2007). Thiamethoxam : A Neonicotinoid Precursor Converted to Clothianidin in Insects and Plants Different Structural Types of Proneonicotinoids.

26. References
Johnson, K. D., O’Neal, M. E., Bradshaw, J. D., & Rice, M. E. (2008). Is preventative, concurrent management of the soybean aphid (Hemiptera: Aphididae) and bean leaf beetle (Coleoptera: Chrysomelidae) possible?
Kandel, A. D. R., Tilmon, K. J., & Shuster, T. L. (2015). Effect of Host Plant Resistance and Seed Treatments on Soybean Aphids ( Hemiptera : Aphididae ) and Their Natural Enemies.
McCarville, M. T., Kanobe, C., MacIntosh, G. C., & O’Neal, M. (2011). What is the economic threshold of soybean aphids (Hemiptera: Aphididae) in enemy-free space?
McCarville, M. T., & O’Neal, M. E. (2013). Soybean aphid (Aphididae: Hemiptera) population growth as affected by host plant resistance and an insecticidal seed treatment.
Mccornack, B. P., & Ragsdale, D. W. (2006). Efficacy of thiamethoxam to suppress soybean aphid populations in Minnesota soybean crop management. Management, (July 2003).
Ragsdale, D. W., McCornack, B. P., Venette, R. C., Potter, B. D., MacRae, I. V, Hodgson, E. W., … Cullen, E. M. (2007). Economic Threshold for Soybean Aphid (Hemiptera: Aphididae).
Ragsdale, D. W., Voegtlin, D. J., Neil, R. J. O., Ragsdale, D. W., & Voegtlin, D. J. (2004). Soybean Aphid Biology in North America.
Tilmon, K. J., Hodgson, E. W., O’Neal, M. E., & Ragsdale, D. W. (2011). Biology of the Soybean Aphid, Aphis glycines (Hemiptera: Aphididae) in the United States.
Venette, R. C., & Ragsdale, D. W. (2004). Assessing the Invasion by Soybean Aphid (Homoptera: Aphididae): Where Will It End?

27. Acknowledgments Dr. Luis Cañas (Advisor) Dr. Andy Michel (Advisor)
Cañas and Michel Lab members
Department of Entomology, The Ohio State University
Funded by The OARDC SEEDs Grants program to LC and AM
Carlos J. Esquivel, MSc.
Department Of Entomology,
The Ohio State University, Wooster, OH