Plant water limitation and its impact on the oviposition preferences of the monarch butterfly (Lepidoptera: Nymphalidae)

Intensifying drought conditions across the western United States due to global climate change are altering plant-insect interactions. Specialist herbivores must find their host plants within a matrix of nonhosts, and thus often rely upon specific plant secondary chemistry for host location and oviposition cues. Climate-induced alterations to plant chemistry could thus affect female selection of larval food plants. Here, we investigated whether host-plant water limitation influenced oviposition preference in a threatened invertebrate: the monarch butterfly (Danaus plexippus). We found that females deposited more eggs on reduced-water than on well-watered narrowleaf milkweed plants (Asclepias fascicularis), but we could not attribute this change to any specific change in plant chemistry. Specialist herbivores, such as the monarch butterfly, which are tightly linked to specific plant cues, may experience shift in preferences under global-change conditions. Understanding oviposition preferences will be important to directing ongoing habitat restoration activities for this declining insect.

Automated summary

Intensifying drought conditions caused by global climate change in the western United States are changing plant-insect interactions. The monarch butterfly, a threatened invertebrate, deposited more eggs on water-limited narrowleaf milkweed plants but the change could not be attributed to specific changes in plant chemistry. Specialist herbivores like the monarch butterfly may experience preference shifts under global climate change. Understanding oviposition preferences is important for habitat restoration for this declining insect.