Dietary cardenolides enhance growth and change the direction of the fecundity-longevity trade-off in milkweed bugs (Heteroptera: Lygaeinae)
Pokharel P, Steppuhn A, Petschenka G. Ecology and evolution, November 2021.
Read the paper Free to read · doi:10.1002/ece3.8402
What this paper is about
Storing a toxin is assumed to cost something. Milkweed bugs were reared with and without dietary cardenolides to find out what.
They grew better with the toxins than without, and the usual trade-off between producing many eggs and living a long time ran in the opposite direction. These insects appear to need the compounds they are defended by.
Summarised here from the abstract below. Not the authors’ words.
Abstract
Sequestration, that is, the accumulation of plant toxins into body tissues for defense, was predicted to incur physiological costs and may require resistance traits different from those of non-sequestering insects. Alternatively, sequestering species could experience a cost in the absence of toxins due to selection on physiological homeostasis under permanent exposure of sequestered toxins in body tissues. Milkweed bugs (Heteroptera: Lygaeinae) sequester high amounts of plant-derived cardenolides. Although being potent inhibitors of the ubiquitous animal enzyme Na+/K+-ATPase, milkweed bugs can tolerate cardenolides by means of resistant Na+/K+-ATPases. Both adaptations, resistance and sequestration, are ancestral traits of the Lygaeinae. Using four milkweed bug species (Heteroptera: Lygaeidae: Lygaeinae) and the related European firebug (Heteroptera: Pyrrhocoridae: Pyrrhocoris apterus) showing different combinations of the traits "cardenolide resistance" and "cardenolide sequestration," we tested how the two traits affect larval growth upon exposure to dietary cardenolides in an artificial diet system. While cardenolides impaired the growth of P. apterus nymphs neither possessing a resistant Na+/K+-ATPase nor sequestering cardenolides, growth was not affected in the non-sequestering milkweed bug Arocatus longiceps, which possesses a resistant Na+/K+-ATPase. Remarkably, cardenolides increased growth in the sequestering dietary specialists Caenocoris nerii and Oncopeltus fasciatus but not in the sequestering dietary generalist Spilostethus pandurus, which all possess a resistant Na+/K+-ATPase. We furthermore assessed the effect of dietary cardenolides on additional life history parameters, including developmental speed, longevity of adults, and reproductive success in O. fasciatus. Unexpectedly, nymphs under cardenolide exposure developed substantially faster and lived longer as adults. However, fecundity of adults was reduced when maintained on cardenolide-containing diet for their entire lifetime but not when adults were transferred to non-toxic sunflower seeds. We speculate that the resistant Na+/K+-ATPase of milkweed bugs is selected for working optimally in a "toxic environment," that is, when sequestered cardenolides are stored in the body.
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"Dietary cardenolides enhance growth and change the direction of the fecundity-longevity trade-off in milkweed bugs (Heteroptera: Lygaeinae) (listing)." Milkweed USA, 2026, https://milkweedusa.com/research/dietary-cardenolides-enhance-growth-and-change-the-direction-of-2021/. Accessed DATE.
Milkweed USA. "Dietary cardenolides enhance growth and change the direction of the fecundity-longevity trade-off in milkweed bugs (Heteroptera: Lygaeinae) (listing)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/research/dietary-cardenolides-enhance-growth-and-change-the-direction-of-2021/.
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title = {Dietary cardenolides enhance growth and change the direction of the fecundity-longevity trade-off in milkweed bugs (Heteroptera: Lygaeinae) (listing)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/research/dietary-cardenolides-enhance-growth-and-change-the-direction-of-2021/},
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