Some adaptations between Danaus plexippus and its food plant, with notes on Danaus chrysippus and Euploea core (Insecta: Lepidoptera)

Abstract

Behaviour of the egg‐laying Monarch in captivity suggests that the concentration and quality of cardiac glycosides in the food plant are not important oviposition cues. The presence of eggs (as previously noted by Urquhart, 1960) and larvae feeding on the food plant, act as mild deterrents. The butterfly's emetic potency (see Table XIII(a)) can sometimes surpass that of the leaves of the host plant itself. Unidentified factors, providing the internal plant environment, are more important as cardiac glycoside storage stimulants than either the quantity or quality of the cardenolides present. In the laboratory D. plexippus oviposited preferentially on a plant with relatively low cardiac glycoside content, but which produced the most powerfully protected (emetic) adult. Metabolic changes during the pharate pupal stage, but also, in the case of Euploea core, in the larval fifth instar, rather than larval sequestration, may account for the major increase or decrease in butterfly toxicity compared with that of the food plant. Temperature does not affect the storage of cardenolides except indirectly by altering metabolic rate. There is no evidence to support the concept that current “physiological cost” of cardenolide storage is high. Like the toad, this butterfly can be assumed to have evolved an enzvmatic system well adjusted to the presence of cardenolides in its bodv tissues.

Milkweed butterfly resistance to plant toxins is linked to sequestration, not coping with a toxic diet

“…It is well established that cardenolides protect monarch butterflies from bird attacks [21] and both monarch and queen butterflies, are mimicry models for the viceroy (Limenitis archippus) [27,28] underlining the effectiveness of cardenolide sequestration as a defence. Moreover, it was shown that across milkweed butterfly species (D. plexippus, the plain tiger, D. chrysippus and E. core) emetic potency acting on predators is linked to the amount of cardenolides stored [29]. Our study thus suggests a mechanism of how the third trophic level can engage in plant-insect coevolution by favouring altered tolerance and use of toxins by herbivores.…”

Dynamics of oviposition in Danaus plexippus (Insecta: Lepidoptera) on milkweed, Asclepias spp

“…Brower (I 969) using this and other pieces of information suggested that female D. plexippus cue in on secondary plant substances, particularly cardiac glycosides and oviposit preferentially on those plants containing large amounts of these compounds. Dixon et al (1978), on the other hand, reported that butterflies consistently selected (except for one aberrant case) plants with the lowest concentration of cardiac glycosides of those plants offered. Their preference in descending order was A .…”

“…The latter two species have been placed into the genus Gomphocarpus by some authors (e.g. Smithers, 1973;Dixon et al, 1978) however Everist (1974) retains them in the genus Ascelpias and we follow his nomenclature. Experimental design was dictated by availability of plants and butterflies and hence some comparisons were not possible.…”

Evolution of latex and its constituent defensive chemistry in milkweeds (Asclepias): a phylogenetic test of plant defense escalation

“…This is further complicated by the fact that many milkweed herbivores sequester cardenolides. For example, Dixon et al. (1978) wrote in passing that fifth instar monarchs sometimes drink latex from plant wounds.…”

“…This is further complicated by the fact that many milkweed herbivores sequester cardenolides. For example, Dixon et al (1978) wrote in passing that fifth instar monarchs sometimes drink latex from plant wounds. One of us (Agrawal) has also observed larvae imbibing latex, but this has only been while very carefully notching a leaf ( Figure 1B), presumably to depressurize the leaf.…”