| Title: | "The Effects of Milkweed Induced Defense on Parasite Resistance in Monarch Butterflies, Danaus plexippus" |
| Author(s): | Tan WH; Tao L; Hoang KM; Hunter MD; de Roode JC; |
| Address: | "Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA. wen-hao.tan@emory.edu. Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA, 30322, USA. Department of Ecology & Evolutionary Biology, University of Michigan, 1105 N. University Avenue, Ann Arbor, MI, 48109, USA" |
| DOI: | 10.1007/s10886-018-1007-4 |
| ISSN/ISBN: | 1573-1561 (Electronic) 0098-0331 (Linking) |
| Abstract: | "Many plants express induced defenses against herbivores through increasing the production of toxic secondary chemicals following damage. Phytochemical induction can directly or indirectly affect other organisms within the community. In tri-trophic systems, increased concentrations of plant toxins could be detrimental to plants if herbivores can sequester these toxins as protective chemicals for themselves. Thus, through trophic interactions, induction can lead to either positive or negative effects on plant fitness. We examined the effects of milkweed (Asclepias spp.) induced defenses on the resistance of monarch caterpillars (Danaus plexippus) to a protozoan parasite (Ophryocystis elektroscirrha). Milkweeds contain toxic secondary chemicals called cardenolides, higher concentrations of which are associated with reduced parasite growth. Previous work showed that declines in foliar cardenolides caused by aphid attack render monarch caterpillars more susceptible to infection. Here, we ask whether cardenolide induction by monarchs increases monarch resistance to disease. We subjected the high-cardenolide milkweed A. curassavica and the low-cardenolide A. syriaca to caterpillar grazing, and reared infected and uninfected caterpillars on these plants. As expected, monarchs suffered less parasite growth and disease when reared on A. curassavica than on A. syriaca. We also found that herbivory increased cardenolide concentrations in A. curassavica, but not A. syriaca. However, cardenolide induction in A. curassavica was insufficient to influence monarch resistance to the parasite. Our results suggest that interspecific variation in cardenolide concentration is a more important driver of parasite defense than plasticity via induced defenses in this tri-trophic system" |
| Keywords: | "Animals Asclepias/*chemistry/metabolism/parasitology Butterflies/*growth & development/physiology Cardenolides/chemistry/isolation & purification/pharmacology Chromatography, High Pressure Liquid Herbivory/drug effects Host-Parasite Interactions Larva/dru;" |
| Notes: | "MedlineTan, Wen-Hao Tao, Leiling Hoang, Kevin M Hunter, Mark D de Roode, Jacobus C eng IOS-1557724/National Science Foundation/ 2018/08/21 J Chem Ecol. 2018 Nov; 44(11):1040-1044. doi: 10.1007/s10886-018-1007-4. Epub 2018 Aug 20" |
