Milkweed sustainability in the Sonoran Desert: A. erosa is more water-efficient compared to two other species

(1) Basis Phoenix High School, Phoenix, Arizona, (2) College of Graduate Studies, Midwestern University, Glendale, Arizona

Cover photo for Milkweed sustainability in the Sonoran Desert: <em>A. erosa</em> is more water-efficient compared to two other species

Monarch butterfly population counts have drastically decreased since the 1980s, and this decline is tied heavily to destruction of Monarch hostplants, milkweed. The Sonoran Desert supports over a dozen species of milkweed, all possible hosts for Monarch caterpillars. The purpose of this experiment was to identify the most water-efficient species of milkweed for propagation in the Sonoran Desert to support Monarch butterfly populations. This experiment tested likely candidates for propagation in the climate of Arizona and Northern Mexico. Three milkweed species (Arizona milkweed, Desert milkweed, and Tropical milkweed) grown in two different volumetric water concentrations were tested. Desert milkweed had the highest germination rate, survival rate, plant mass, and water retention capability. Thus, Desert milkweed was most effective at absorbing and utilizing water resources compared to the other species. Interestingly, Desert milkweed’s average height was taller in the lower volumetric water level, but for overall plant mass, the higher the water level, the larger the mass. Desert milkweed is the best candidate for widespread propagation in the Sonoran Desert. Given that this research identified a native species of milkweed that can grow with minimal resources, future conservation efforts could use Desert milkweed as a prime species for mass-propagation conservation projects with minimal strain on local resources. The conclusions we drew will aid Monarch conservationists in preserving Monarch habitats during drought conditions.

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