The La Sal Mountains in southeastern Utah are separated from other mountain ranges of the Southwest. The small alpine areas are particularly isolated; there are disjunct populations and endemic species of plants but the status of arthropod species is unknown. The La Sals face many threats: climate change, livestock grazing and burgeoning recreational pressures. In addition, 35 non-native mountain goats (Oreamnos americanus) were introduced in 2013 and 2014; the population is now estimated to exceed 100. Very little information is available on La Sal alpine arthropods; a search of over 100 museum collections databases for the La Sals above 3400 m yielded 19 specimens. The goats were introduced before we could conduct baseline surveys, but it is important to try to characterize the alpine arthropod communities given the significant disturbances to the alpine zone already occurring. We began baseline inventory fieldwork in early summer 2014, and continued through 2019, with pitfall and pollinator cup trapping and net capture surveys of pollinators as well. Here we present Hymenoptera and Lepidoptera net capture data from 2016-2019 at three sites.
Results/Conclusions
Fifty-eight species of flowering plants were documented as host plants (or at least landing sites) for at least one species of Lepidoptera or Hymenoptera. Individual plant species were hosts for zero to 14 Hymenoptera, and zero to 17 Lepidoptera. We documented a total of 111 Hymenoptera taxa over the three years. Number of Hymenoptera taxa caught ranged from 38-84; Lepidoptera taxa varied from 48-59 over the four years. There was considerable spatial and temporal variability in the pollinator community, with species added to the total list each year but some seen in previous years not observed later. Individual species use of flowering plants also varied over the years, but there were interesting patterns among the pollinator taxa. Ordination (NMS) of Hymenoptera on flowers indicated that within years populations of some taxa (genera or families) at different sites used flower resources similarly, but use differed between years (e.g. Bombus, Megachilidae); Lepidoptera use patterns were less clear (e.g., Lycaenidae, Noctuidae). This is likely because many Hymenoptera are foraging for pollen as well as nectar and preferences and adaptations to acquire pollen may restrict which floral resources are accessible.