Lepidoptera

The inventory and monitoring of Grand Canyon Lepidoptera is part of a larger Terrestrial Ecosystem Monitoring project involving plants, vertebrates and arthropods. Although this website focuses on the Lepidoptera, we are inventorying and monitoring all arthropods in the riparian zonal along the Colorado River in Grand Canyon. The purpose of the arthropod studies are first to inventory and characterize the terrestrial arthropod fauna associated with the different river flow stage riparian environments along the Colorado River in Grand Canyon (GC). Are there distinct arthropod communities from the river shoreline through the tamarisk-dominated new High water zone vegetation to the mesquite desert vegetation zone that marks the high water zone prior to the operation of the dam? Are certain arthropod taxa more sensitive to habitat changes than other taxa? Second, how are the riparian arthropod community dynamics impacted by river level fluctuations resulting from Glen Canyon Dam operation. The joint monitoring program (NAU & UNM) will provide information on the effects of dam operation on riparian arthropods. Our monitoring will be integrated with corresponding data representing vegetation and vertebrate animals produced from this same research program. Here we focus on the nocturnal Lepidoptera.

Objectives: Principal objectives for our arthropod studies are to: 1) Determine the species composition and relative abundance's of arthropods associated with the old high water zone, the new high water zone, and the fluctuation zone environments. 2) Determine microhabitat associations for those arthropods such as water zone preferences and host plant relationships. 3) Relate arthropod species composition to vegetation and vertebrate animals across the three hydrologic riparian zones. 4) Initiate a sampling design for comparative monitoring of arthropod communities across the three riparian hydrologic zones over time. 6) To develop a reference collection for Grand Canyon riparian arthropod specimens representing those taxa found during this project, and 7) To provide basic ecological information on Grand Canyon riparian arthropods to integrate with vegetation and vertebrate animal information produced from this and other research projects, and to provide arthropod data for other biological, cultural, and physical resource information needs, and to assess geomorphic scale trends in populations.

Methods: Study sites and sampling points. A total of 34 sites were selected for focused sampling of all terrestrial arthropods along the Colorado River in Grand Canyon. Four of the sites were sampled in all three years of 2001, 2002, and 2003 (46.7R, 65.3L, 122.8L, and 198.0L). For each year we sampled 10 new sites each year. The purpose of selecting new sites was to increase the total number of study sites to obtain a better representation for the canyon. Three transects were established at each site, one transect representing each of the three water level zones: water's edge, new high water zone, and old high water zone. Each transect was 100 meters long, partitioned into 10 sampling points at 10 meter intervals. The transects were laid out parallel to each other, beginning 20–100 m upstream or downstream from the camp, depending on constraints imposed by the local topography. The transect representing the fluctuation zone (Shoreline) was situated one meter above the existing daily high-water shore line. The actual daily shoreline fluctuation zone varies over time, depending upon water releases from Glen Canyon Dam. The transects covering the Old High Water Zone (OHWZ) and the New High Water Zone (NHWZ) were situated in the middle of each of those zones' range of elevation above shoreline. The NHWZ was the hydrologic zone just above the shoreline and was characterized by vegetation dominated by Tamarisk. The OHWZ was the highest elevation hydrologic zone and was characterized by mesquite, desert shrubs and acacia. In terms of size the OHWZ occupies the greatest amount of area for any given site (mean=8055m 2 SE=1033), the NHWZ occupies the next largest amount of beach habitat (mean=5598m 2 SE=688), and the shoreline occupies the smallest area (mean=2251m 2 SE=314). These estimates are based on 66 sites selected throughout the study area.

Sampling: Moths were sampled at the same time as other taxa, twice during 2001 and 2003 and three times in 2002. The first sampling period in was April/May, and the second was August/September. Additional collecting occurred in 2002 during June-July. Early and late summer seasons likely support many different arthropod taxa activity periods. Early summer and late summer sampling periods were chosen to accommodate the potential seasonal variation in active arthropod taxa.

Malaise traps (tent-like flight interception traps) and black light traps were used to sample flying insects in the day and night, respectively. One malaise trap was installed in the middle of each of the 100 meter sampling transects in each of the three water zones at each site. The traps were erected in the afternoon (4:00 pm) at the beginning of each site visit, and disassembled the next morning (10:00 am) before departing the site. Each of the three malaise trap containers was emptied and the insects were sorted in the field, and placed into small glass vials with 70% ethanol, or small plastic containers with naphthalene, depending upon the insects and which preservative is appropriate. Those samples were then taken to the lab following each river trip.  We used black-light (UV) traps to sample night-flying insects. Our black light traps consisted of a fluorescent black light suspended over a 3-gallon bucket containing a pyrethroid insecticide no-pest strip. A large plastic funnel (40 cm top diameter, 10 cm bottom diameter) was placed on top of the bucket, and the light source suspended just inside the top of the funnel. Each light trap was connected to a power source with a timing device. The lights were turned on at sunset, and run until midnight (12:00 am). The light trap buckets were collected at sunrise, and all insects were removed and placed into vials with ethanol or naphthalene.

ALL OF THE IDENTIFICATIONS ON THE IMAGES AND IN THE FAMILY DATABASES ARE TENTATIVE. WE WILL PROVIDE UPDATES FOR TAXA WHERE THE IDENTIFICATIONS HAVE BEEN VERIFIED. PLEASE DO NOT USE IDENTIFICATIONS WITHOUT CONFIRMING WITH US FIRST. Comments, corrections, and additions most welcome.