Transcript The Effects of Mosquito-Control Applications of Permethrin on Monarch Danaus plexippus

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
Background
H3C
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CH3
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Cl
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Cl
• Permethrin (Mosquito spray)
– Pyrethroid pesticide
– Sprayed in ULV form as mosquito adulticide
– Applied to wooded areas, where milkweed can
grow
Background
http://www.mbsf.org/news.html
• Monarchs: non-target insect
• Larvae (caterpillars) are terrestrial
• Only eat milkweed (Asclepias)
Background
• Little research conducted on effect on nontarget invertebrates
• Only peer-reviewed field study (Jensen et
al): immediate mortality in aquatic and
night-flying insects
Materials and Methods: Part I
QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
• 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
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)
Results (Part I): Overall larval
mortality
Proportion dead
1
0.8
153
111
0.6
32
Treated
0.4
0.2
Control
81
0
1st instar
136
21
2nd instar
3rd instar
Beginning instar
Results (Part I): Variables
affecting mortality
Variable
Beginning instar
Days on treated leaf
Days since spraying
Coefficient Std. error p-value
-0.8220
-1.2589
-0.0106
0.3661
0.3279
0.0595
0.0248
0.0001
0.8578
Materials and Methods: Part II
QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
• 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
Hypotheses (Part II)
• Larvae exposed to sublethal solution will be
affected:
– Slower development time
– Smaller adult mass
• Oil diluent will have no effect
Mean development time (days)
Results (Part II): Total
development time
35
30
25
20
Control
4 6 6
7 4 5 2
15
Oil
8 9 8
0.1% Solution
0.5% Solution
10
5
0
2nd instar
3rd instar
Beginning instar
4th instar
Results (Part II): Adult mass
Variable
Beginning instar
Oil
0.1% Solution
0.5% Solution
Coefficient Std. Error
-0.0101
0.0024
-0.0242
-0.0864
0.0314
0.0089
0.0182
0.0418
p-value
0.2639
0.8935
0.1913
0.0436
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
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
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