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Lethal and Sub-lethal Effects of Resmethrin on Nontargeted Species

Lethal and Sub-lethal Effects of Resmethrin on Nontargeted Species. Meredith Blank 2006. Background. Resmethrin- synthetic pyrethroid made from chrysanthemum flowers . http://www.beyondblossoms.com/blog/wp-content/chrysanthemums_01.jpg. Background.

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Lethal and Sub-lethal Effects of Resmethrin on Nontargeted Species

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  1. Lethal and Sub-lethal Effects of Resmethrin on Nontargeted Species Meredith Blank 2006

  2. Background • Resmethrin- synthetic pyrethroid made from chrysanthemum flowers http://www.beyondblossoms.com/blog/wp-content/chrysanthemums_01.jpg

  3. Background • Resmethrin—contact poison that quickly penetrates the nerve system of the insect • Sprayed throughout Twin Cities by MMCD to control mosquito population

  4. Societal Implications • Increased prevalence of West Nile Virus= MMCD sprays resmethrin more to control mosquito populations • Effects on many nontargeted species not yet known

  5. Purpose • To determine effects of resmethrin on monarch butterflies (Danaus plexippus), milkweed bugs (Lygaeus kalmii),and houseflies (Musca Domestica) Acertainslantoflight.blogspot.com troyb.com

  6. Previous Studies • Dr. Oberhauser and Sara Brinda (2003-04) The Effects of Mosquito-Control Applications of Permethrin on Monarch Butterfly (Danaus plexippus) Larvae • Rosemary Lelich (2004-05) Effects of Resmethrin Spray on Monarch Butterflies (Danaus plexippus)

  7. Methods: Preparing Monarch Larvae for Spraying

  8. Methods: Spray Set-up National Sports Center, Blaine, Minnesota

  9. Methods: Spray Transect 170 m 120 m 75 m 30 m 15 m Spray Path 15 m Downwind Upwind Distance from Spray Path

  10. Methods: Spray Transect 170 m 120 m 75 m 30 m 15 m Spray Path 15 m Downwind Upwind Distance from Spray Path

  11. Goals and Hypotheses Goal 1: See if monarch larvae exposed closer to spray path would have a lower survival rate Hypothesis 1: Monarch larvae exposed to resmethrin at closer distances to the spray would have a lower survival rate

  12. Results on Hypothesis 1

  13. Goals and Hypotheses Goal 2: See if monarchs exposed to resmethrin would emerge as smaller adults Hypothesis 2: Monarch larvae exposed to resmethrin would become smaller adults

  14. Results on Hypothesis 2

  15. Goals and Hypotheses Goal 3: See if there were lethal effects on milkweed bugs and houseflies Hypothesis 3: Milkweed bugs and houseflies exposed to resmethrin would have a lower survival rate

  16. Results on Hypothesis 3 Table 3: Mean Survival of Milkweed Bugs; linear regression t-test gave p = 0.33

  17. Results on Hypothesis 3 Table 4: Mean Survival of House Flies; linear regression t-test gave p = 0.26

  18. Goals and Hypotheses Goal 4: See how long after spraying resmethrin would affect monarch butterflies Hypothesis 4: Monarch larvae directly exposed to resmethrin would have a lower survival rate than monarch larvae fed resmethrin-sprayed plants 1, 2, or 4 days later

  19. Results on Hypothesis 4 Table 5: Mean Survival Dependent on Day Exposed A linear regression t-test gave p-value = 0.0022

  20. Conclusion • Only the hypothesis that the days since spraying increased monarch larvae survival rate increased was accepted (p = 0.0022, using a significance level of p = 0.05)

  21. Conclusion • Monarchs sprayed with resmethrin did not have smaller masses (p = 0.21) • Resmethrin did not have lethal effects on milkweed bugs (p = 0.33) • Resmethrin did not have lethal effects on houseflies (p = 0.26) • Survival rate did not increase as distance from spray path increased (p = 0.16)

  22. Future Studies • Test at more variable wind speeds and different summer temperature conditions • Study other beneficial non-targeted species

  23. Acknowledgments • Dr. Oberhauser • University of Minnesota monarch lab • Ms. Fruen and Team Research

  24. Lethal and Sub-lethal Effects of Resmethrin on Nontargeted Species Meredith Blank 2006

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