Desert Milkweed (Asclepias erosa) as a Midsummer Resource for Arthropod Communities in the Great Basin Desert.

In arid ecosystems, consumer communities are often structured by strong temporal fluctuations in resource availability. During midsummer in the Great Basin Desert, high temperatures and declining soil moisture cause many early-season plants to senesce, potentially concentrating arthropod activity on the few species that remain physiologically active. We characterized arthropod assemblages associated with the desert milkweed (Asclepias erosa) to evaluate its potential role as a focal plant during this seasonal period of reduced floral and vegetative productivity. Arthropods were surveyed on randomly selected plants across four sites in northern Nevada during June 2025 using standardized observations, during which arthropod identity, behavior, and location on the plant were recorded. Across 41 plants, we recorded 1779 arthropod individuals representing 67 morphospecies across six orders. Arthropods occupied nearly all plants surveyed and used all aboveground plant structures, including flowers, leaves, and stems. Community composition was highly skewed toward a few dominant taxa, with two dipteran morphospecies accounting for over 40% of all recorded individuals. Furthermore, the majority of morphospecies were rare in their distribution, occurring on fewer than three plants. Flowering plants supported significantly greater arthropod abundance and morphospecies richness than vegetative plants; however, most vegetative individuals also harbored arthropods. While nectar-feeding individuals accounted for many observations, numerous arthropods were resting, moving among plant structures, or occupying stems and leaves without actively feeding, indicating that A. erosa may also provide structural habitat, refuge from thermal stress, and opportunities for predation or other trophic interactions. These results provide baseline natural history data on plant-arthropod interactions in Great Basin Desert system and suggest that A. erosa may function as a localized resource patch supporting diverse arthropod assemblages during the midsummer period of resource limitation.