The Effects of Mosquito-Control Applications of Permethrin on Monarch Butterfly (Danaus plexippus) Larvae

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The Effects of Mosquito-Control Applications of
Permethrin on Monarch Butterfly (Danaus
plexippus) Larvae
http//www.hwcn.org/link/hmm/mbcat.JPG

• By Sara Brinda
• 2003-2004

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Background

• Permethrin (Mosquito spray)
• Pyrethroid pesticide
• Sprayed in ULV form as mosquito adulticide
• Applied to wooded areas, where milkweed can grow

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Background
http//www.mbsf.org/news.html

• Monarchs non-target insect
• Larvae (caterpillars) are terrestrial
• Only eat milkweed (Asclepias)

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Background

• Little research conducted on effect on non-target
  invertebrates
• Only peer-reviewed field study (Jensen et al)
  immediate mortality in aquatic and night-flying
  insects

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Materials and Methods Part I

• Common milkweed (A. syriaca) collected from
  permethrin-treated areas
• Larvae fed with treated milkweed leaves
• Three variables
• Days between spraying and initial exposure
• Days spent on treated leaf
• Beginning instar

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Hypotheses (Part I)

• Milkweed collected from permethrin-treated areas
  will have lethal effect on monarch larvae
• Larval mortality rates will be higher
• Leaves treated more recently with permethrin
• Exposed to treated leaves for greater period of
  time
• Exposed to milkweed during earlier instars
  (growth stages)

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Results (Part I) Overall larval mortality
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Results (Part I) Variables affecting mortality
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Materials and Methods Part II

• Leaves treated in lab with oil solution, 0.1
  solution, or 0.5 solution
• Leaves fed to monarchs for entire lifetime
• Larval mass and instar monitored daily
• Adult mass recorded

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Hypotheses (Part II)

• Larvae exposed to sublethal solution will be
  affected
• Slower development time
• Smaller adult mass
• Oil diluent will have no effect

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Results (Part II) Total development time
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Results (Part II) Adult mass
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Further Study

• Permethrin effectiveness on mosquitoes vs.
  nontargets
• How effective
• Effective for how long?
• More research needed on mosquito adulticide
  effects on non-target insects

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Acknowledgements

• Dr. Karen Oberhauser
• Everyone who worked in the lab this summer
• Metropolitan Mosquito Control District,
  especially Dr. Stephen Manwieler
• Ms. Lois Fruen
• Team Research
• Beth Brinda

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The Effects of Mosquito-Control Applications of
Permethrin on Monarch Butterfly (Danaus
plexippus) Larvae
http//www.hwcn.org/link/hmm/mbcat.JPG
By Sara Brinda 2003-2004