Milkweed Matters: Monarch butterfly (Lepidoptera: Nymphalidae) survival and development on nine Midwestern milkweed species

Authors: POCIUS, VICTORIA - Iowa State University; DEBINSKI, DIANE - Iowa State University; PLEASANTS, JOHN - Iowa State University; Bidne, Keith; Hellmich Ii, Richard; BROWER, LINCOLN - Sweet Briar College

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2017
Publication Date: 9/7/2017
Citation: Pocius, V.M., Debinski, D.M., Pleasants, J.M., Bidne, K.G., Hellmich II, R.L., Brower, L.P. 2017. Milkweed Matters: Monarch butterfly (Lepidoptera: Nymphalidae) survival and development on nine Midwestern milkweed species. Environmental Entomology. 46(5):1098-1105. https://doi.org/10.1093/ee/nvx137.
DOI: https://doi.org/10.1093/ee/nvx137

Interpretive Summary: The population of monarch butterflies east of the Rocky Mountains has experienced a significant decline over the past twenty years. In order to increase monarch numbers in the breeding range, habitat restoration that includes planting milkweed plants is essential. Milkweeds in the genus Asclepias are the only host plants for larval monarch butterflies, but larval performance and survival across nine milkweeds native to the Midwest is not well documented. We examined development and survival of monarchs from early caterpillar to adulthood on nine milkweed species native to Iowa: A. syriaca (common milkweed), A. incarnata (swamp milkweed), A. tuberosa (butterfly milkweed), A. verticillata (whorled milkweed), A. speciosa (showy milkweed), A. exaltata (poke milkweed), A. sullivantii (prairie milkweed), A. hirtella (tall green milkweed), and Cynanchum laeve (honeyvine milkweed). In greenhouse experiments, the probability of monarchs surviving to adulthood was different among milkweed species. Fewer larvae that fed on A. hirtella (tall green milkweed) and A. sullivantii (prairie milkweed) reached adulthood compared to the other milkweed species. Our results show that monarch butterflies can survive on all nine milkweed species, but that the expected survival probability varied from 30% to 75% among the nine species. This information is useful to all groups interested in restoring habitat for monarch butterflies.

Technical Abstract: The population of monarch butterflies east of the Rocky Mountains has experienced a significant decline over the past twenty years. In order to increase monarch numbers in the breeding range, habitat restoration that includes planting milkweed plants is essential. Milkweeds in the genus Asclepias are the only host plants for larval monarch butterflies, but larval performance and survival across nine milkweeds native to the Midwest is not well documented. We examined development and survival of monarchs from early caterpillar to adulthood on nine milkweed species native to Iowa: A. syriaca (common milkweed), A. incarnata (swamp milkweed), A. tuberosa (butterfly milkweed), A. verticillata (whorled milkweed), A. speciosa (showy milkweed), A. exaltata (poke milkweed), A. sullivantii (prairie milkweed), A. hirtella (tall green milkweed), and Cynanchum laeve (honeyvine milkweed). Results show that fewer monarchs that fed on A. hirtella survived than those that fed on A. tuberosa, or A. exaltata. Also, fewer monarchs that consumed A. sullivantii survived than those that consumed A. exaltata. When survival was analyzed in five-day increments, there were no differences in the proportion of larvae that survived on each milkweed species, although there was lower survival on C. laeve during the first five days, on A. sullivantii for the first ten days, and both A. hirtella and A sullivantii during the first 14 days. Larval duration (days), pupal duration (days), pupal mass, pupal length, and adult mass were not significantly different among the nine species. Interestingly, both amount and concentration (% lipids of total body mass) of adult lipids were different among species even though adult mass was not different. Adults that fed on A. exaltata, A. incarnata, and A. syriaca had higher lipid content than those that fed on A. hirtella as larvae. Our results show that in greenhouse experiments monarch butterflies can survive on all nine milkweed species, but that the expected survival probability varied from 30% to 75%. This information is useful to all groups interested in restoring habitat for monarch butterflies.