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

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Presentation on theme: "Lethal and Sub-lethal Effects of Resmethrin on Nontargeted Species Meredith Blank 2006."— Presentation transcript:

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

2 Background Resmethrin- synthetic pyrethroid made from chrysanthemum flowers 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.comtroyb.com

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

7 Methods: Preparing Monarch Larvae for Spraying Treatment TypeStudy Procedure 0-day2 nd and 4 th instar larvae were sprayed directly with resmethrin 1-day2 nd and 4 th instar larvae were fed leaves from sprayed plants one day after spraying 2-day2 nd and 4 th instar larvae were fed leaves from sprayed plants two days after spraying 4-day2 nd and 4 th instar larvae were fed leaves from sprayed plants four days after spraying

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

9 Methods: Spray Transect Transect A 3 mw plants and 1 mw plant w/ larvae +2 cages 3 mw plants and 1 mw plant w/ larvae +2 cages 3 mw plants and 1 mw plant w/ larvae +2 cages Transect B 3 mw plants and 1 mw plant w/ larvae+2 cages 170 m 120 m 75 m 30 m 15 m Spray Path 15 m Downwind Upwind Distance from Spray Path

10 Methods: Spray Transect Transect A 3 mw plants and 1 mw plant w/ larvae +2 cages 3 mw plants and 1 mw plant w/ larvae +2 cages 3 mw plants and 1 mw plant w/ larvae +2 cages Transect B 3 mw plants and 1 mw plant w/ larvae+2 cages 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 Location Number of Cages Mean Survival Standard Error Transect A Transect B Control Control Control Table 3: Mean Survival of Milkweed Bugs; linear regression t- test gave p = 0.33

17 Results on Hypothesis 3 Location Numbers of Cages Mean Survival Standard Error Transect A Transect B Control Control Control 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 Treatment TypeMean Survival 0-day day day day Table 5: Mean Survival Dependent on Day Exposed A linear regression t-test gave p-value =

20 Conclusion Only the hypothesis that the days since spraying increased monarch larvae survival rate increased was accepted (p = , 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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