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

Background Resmethrin- synthetic pyrethroid made from chrysanthemum flowers content/chrysanthemums_01.jpg

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

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

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

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)

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

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

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

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

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

Results on Hypothesis 1

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

Results on Hypothesis 2

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

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

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

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

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 =

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)

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)

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

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

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