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)

North-Central Population Migration Pattern (

North-Central Population Migration Pattern ( Western Population: 500 miles

North-Central Population Migration Pattern ( 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 nosus,_workers_tending_milkweed_aphids,I_ANT74.jpg

Methods for First Goal: Falcon Heights Park, MN ( )

Monitoring Monarch Larvae Photo by Author

Monitoring Presence of Aphids Photo by Author

Monitoring Herbivory Photo by Author

Factors in Monarch Larvae Mortality Instar Stage vs. Cause of Death (chi-square value=21.577, df=6, p= )

Factors in Monarch Larvae Mortality Presence of Aphids Egg Survival vs. Presence of Aphids (chi- square value=17.953, df=4, p= ) 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)

Factors in Monarch Larvae Mortality Herbivory Egg Survival vs. Herbivory of Milkweed Plant (chi-square value=10.386, df=2, p= ) 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= )

Factors in Monarch Larvae Mortality Position 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 (

Egg (

First-instar (

Second-instar (

Third-instar (

Fourth-instar (

Fifth-instar (

Methods for Second Goal Falcon Heights Park, MN ( ) Monitoring Monarch Larvae

Survival of Monarch Eggs & Larvae

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

Methods for Third Goal ( & modified by author)

Tachinid Fly Parasitism Number of Monarch Larvae Number of Larvae Parasitized Number of Tachinid Flies Hatched 12358

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