Defense of Milkweed Bugs (Heteroptera: Lygaeinae) against Predatory Lacewing Larvae Depends on Structural Differences of Sequestered Cardenolides
Pokharel P, Sippel M, Vilcinskas A and others. Insects, July 2020.
Read the paper Free to read · doi:10.3390/insects11080485
What this paper is about
Two European milkweed bugs take their cardenolides from quite different plants, one from pheasant's eye and one from foxglove. Both are protected by what they store.
The authors tested them against predatory lacewing larvae and found protection depended on which cardenolide structures the bug had taken up, not merely on how much.
Summarised here from the abstract below. Not the authors’ words.
Abstract
Predators and parasitoids regulate insect populations and select defense mechanisms such as the sequestration of plant toxins. Sequestration is common among herbivorous insects, yet how the structural variation of plant toxins affects defenses against predators remains largely unknown. The palearctic milkweed bug Lygaeus equestris (Heteroptera: Lygaeinae) was recently shown to sequester cardenolides from Adonis vernalis (Ranunculaceae), while its relative Horvathiolus superbus also obtains cardenolides but from Digitalis purpurea (Plantaginaceae). Remarkably, toxin sequestration protects both species against insectivorous birds, but only H. superbus gains protection against predatory lacewing larvae. Here, we used a full factorial design to test whether this difference was mediated by the differences in plant chemistry or by the insect species. We raised both species of milkweed bugs on seeds from both species of host plants and carried out predation assays using the larvae of the lacewing Chrysoperla carnea. In addition, we analyzed the toxins sequestered by the bugs via liquid chromatography (HPLC). We found that both insect species gained protection by sequestering cardenolides from D. purpurea but not from A. vernalis. Since the total amount of toxins stored was not different between the plant species in H. superbus and even lower in L. equestris from D. purpurea compared to A. vernalis, the effect is most likely mediated by structural differences of the sequestered toxins. Our findings indicate that predator-prey interactions are highly context-specific and that the host plant choice can affect the levels of protection to various predator types based on structural differences within the same class of chemical compounds.
Abstract reproduced from the published paper, which is licensed CC BY. Copyright remains with the authors.
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"Defense of Milkweed Bugs (Heteroptera: Lygaeinae) against Predatory Lacewing Larvae Depends on Structural Differences of Sequestered Cardenolides (listing)." Milkweed USA, 2026, https://milkweedusa.com/research/defense-of-milkweed-bugs-heteroptera-lygaeinae-against-predatory-lacewing-2020/. Accessed DATE.
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title = {Defense of Milkweed Bugs (Heteroptera: Lygaeinae) against Predatory Lacewing Larvae Depends on Structural Differences of Sequestered Cardenolides (listing)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/research/defense-of-milkweed-bugs-heteroptera-lygaeinae-against-predatory-lacewing-2020/},
note = {Accessed DATE}
}