studying effects of natural enemies on survival of monarch butterfly larvae (danaus plexippus) to...
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Studying Effects of Natural Enemies on Survival of Monarch Butterfly Larvae (Danaus
plexippus) to Aid in Monarch Conservation
Emily Nimmer
2007
Monarch Butterflies (Danaus plexippus)
http://www.calliebowdish.com/Pictures/Butterflypicture-8.jpg
North-Central Population Migration Pattern
(http://www.monarchlab.umn.edu/biology/gen3-4.aspx)
North-Central Population Migration Pattern
(http://www.monarchlab.umn.edu/biology/gen3-4.aspx)
Western Population:
500 miles
North-Central Population Migration Pattern
(http://www.monarchlab.umn.edu/biology/gen3-4.aspx)
3,000 miles
Purpose
• To investigate monarch larvae mortality due to the natural controls of predation and parasitism
First Goal
• To identify factors that influence mortality rates of monarch eggs and larvae
Background: First Goal
• Prysby (2004) showed only 5% of monarch eggs survive a 24-hour period when exposed to aphids
Background: First Goal
• Prysby (2004) showed only 5% of monarch eggs survive a 24-hour period when exposed to aphids
• Oberhauser (2003) showed that aphids are known to attract ants
Background: First Goal
• Prysby (2004) showed only 5% of monarch eggs survive a 24-hour period when exposed to aphids
• Oberhauser (2003) showed that aphids are known to attract ants
• Oberhauser (2003) also showed that ants are predators of monarch eggs and larvae
Ants Tending Aphids
http://www.discoverlife.org/IM/I_ANT/0000/320/Forelius_pruinosus,_workers_tending_milkweed_aphids,I_ANT74.jpg
Methods for First Goal:Falcon Heights Park, MN
(http://maps.google.com )
Monitoring Monarch Larvae
Photo by Author
Monitoring Presence of Aphids
Photo by Author
Monitoring Herbivory
Photo by Author
Factors in Monarch Larvae MortalityInstar Stage vs. Cause of Death (chi-square value=21.577, df=6,
p=0.00144)
0
20
40
60
80
100
120
140
160
Unknown Gone Egg SuckedOut
Egg Chewed
Cause of Death
Number of Monarch Eggs/Larvae
EggsFirst-InstarsSecond-Instars
Factors in Monarch Larvae MortalityPresence of Aphids
0
20
40
60
80
100
120
140
160
180
0 1–10 10–100 100–1000 > 1000
Number of Aphids
Number of Eggs
Dead
Alive
0
5
10
15
20
25
30
0 1–10 10–100 100–1000 > 1000
Number of Aphids
Number of First Instars
Dead
Alive
0
5
10
15
20
25
30
0 1–10 10–100 100–1000 > 1000
Number of Aphids
Number of Second Instars
Dead
Alive
Egg Survival vs. Presence of Aphids (chi-square value=17.953, df=4, p=0.00126)
Second-Instar Survival vs. Presence of Aphids (chi-square value=4.05, df=4, p=0.399)
First-Instar Survival vs. Presence of Aphids (chi-square value=9.87, df=4, p=0.0428)
0
10
20
30
40
50
60
0 <5 5–25
Percentage of Herbivory
Number of Second Instars
Dead
Alive
0
10
20
30
40
50
60
70
0 <5 5–25
Percentage of Herbivory
Number of First Instars
Dead
Alive
0
50
100
150
200
250
0 <5 5–25
Percentage of Herbivory
Number of Eggs
Dead
Alive
Factors in Monarch Larvae MortalityHerbivory
Egg Survival vs. Herbivory of Milkweed Plant (chi-square value=10.386, df=2, p=0.00556)
Second-Instar Survival vs. Herbivory of Milkweed Plant (chi-square value=3.254, df=2, p=0.197)
First-Instar Survival vs. Herbivory of Milkweed Plant (chi-square value=10.358, df=2, p=0.00563)
0
5
10
15
20
25
30
35
Apex Buds of Plant Bottom of Leaf Top of Leaf
Position of Larvae on Milkweed Plant
Number of Second Instars
Dead
Alive
0
10
20
30
40
50
60
Apex Buds of Plant Bottom of Leaf Top of Leaf
Position of Larvae on Milkweed Plant
Number of First Instars
Dead
Alive
0
50
100
150
200
250
300
Apex Buds of Plant Bottom of Leaf Top of Leaf
Position of Eggs on Milkweed Plant
Number of Eggs
Dead
Alive
Factors in Monarch Larvae MortalityPosition of Monarch Larvae on Milkweed Plant
Egg Survival vs. Position of Larvae on Milkweed Plant (chi-square value=4.251, df=3, p=0.236)
Second-Instar Survival vs. Position of Larvae on Milkweed Plant (chi-square value=0.548, df=3, p=0.908)
First-Instar Survival vs. Position of Larvae on Milkweed Plant (chi-square value=5.777, df=3, p=0.123)
Second Goal
• To determine mortality and survival rates of monarch eggs and larvae
Background: Second Goal
• Borkin (1982) and Prysby et. al (2001) focused on overall instar mortality
Monarch Larvae Instar Stages
(http://www.mlmp.org/monitoring/Guide/InstarImages/5_instars_c.jpg)
Egg
(http://www.mlmp.org/monitoring/Guide/InstarImages/5_instars_c.jpg)
First-instar
(http://www.mlmp.org/monitoring/Guide/InstarImages/5_instars_c.jpg)
Second-instar
(http://www.mlmp.org/monitoring/Guide/InstarImages/5_instars_c.jpg)
Third-instar
(http://www.mlmp.org/monitoring/Guide/InstarImages/5_instars_c.jpg)
Fourth-instar
(http://www.mlmp.org/monitoring/Guide/InstarImages/5_instars_c.jpg)
Fifth-instar
(http://www.mlmp.org/monitoring/Guide/InstarImages/5_instars_c.jpg)
Methods for Second Goal
Falcon Heights Park, MN(http://maps.google.com )
Monitoring Monarch Larvae
Survival of Monarch Eggs & Larvae
Figure 17: Survival of Monarch Larvae to Third Instar
0
50
100
150
200
250
300
350
400
1 2 3 4 5 6 7 8 9 10
Day
Number of Eggs/Larvae
EggsFirst-InstarSecond-InstarThird-Instar
Third Goal
• To determine the rate of parasitism of monarch larvae by tachinid flies (Lespesia archippivora)
Tachinid Fly (Lespesia archippivora)
Photo by Kaitlyn Creasey
Background: Third Goal
• Creasey (2007) showed that monarch larvae are killed every time they are parasitized by a tachinid fly
Background: Third Goal
• Creasey (2007) showed that monarch larvae are killed every time they are parasitized by a tachinid fly
• Prysby (2004) found tachinid parasitism rates in TX, WI, and LA between 11.5 and 43%– Also cited tachinid parasitism in Mexico between
70 and 98%
Background: Third Goal
• Creasey (2007) showed that monarch larvae are killed every time they are parasitized by a tachinid fly
• Prysby (2004) found tachinid parasitism rates in TX, WI, and LA between 11.5 and 43%– Also cited tachinid parasitism in Mexico between
70 and 98%
• Creasey (2007) and Oberhauser et al. (2007) found tachinid parasitism rates in MN between 6 and 13% for 2000-2006
Methods for Third Goal
(http://geography.about.com/library/blank/mn.jpg & modified by author)
Tachinid Fly Parasitism
Number of Monarch Larvae
Number of Larvae
Parasitized
Number of Tachinid
Flies Hatched
123 5 8
Conclusions
• Predation in eggs and first-instars can be related to ants
Conclusions
• Predation in eggs and first-instars can be related to ants
• 3% of eggs laid by one female survive to third-instar stage
Conclusions
• Predation in eggs and first-instars can be related to ants
• 3% of eggs laid by one female survive to third-instar stage
• 4% of monarch larvae parasitized by tachinid flies
Future Work
• Continue predation research on third-, fourth-, and fifth-instar larvae
Future Work
• Continue predation research on third-, fourth-, and fifth-instar larvae
• Monitor tachinid fly parasitism to further understand tachinid cycles
• Team Research• Alma de Anda• Reba Betalden• Dr. Karen
Oberhauser• Monarch Lab• Lois Fruen
Acknowledgements
Studying Effects of Natural Enemies on Survival of Monarch Butterfly Larvae (Danaus
plexippus) to Aid in Monarch Conservation
Emily Nimmer
2007