Samantha Smith and Dr. Riley Nelson, Biology

Introduction

Mount Timpanogos, with an elevation of 3,582 meters, is home to an amazing array of insect species. Through much previous effort, many have studied the insects found in American Fork Canyon leading up to Mount Timpanogos. They have still barely scratched the surface of the abundant biodiversity on the mountain. Varied temperature regimes can cause changes in insects’ life cycle and the length of their feeding period, making the collections at different elevations of Mount Timpanogos during different years of particularly great value (Petitt et al 1991). Thus the value of collections along Mount Timpanogos is two-fold; both to study the biodiversity and to study the effect different temperature regimes may have on their life cycle.

Agromyzidae is a family of flies (Insecta: Diptera) that is not well documented throughout all of Utah, and particularly along American Fork Canyon. In discussions with my mentor Dr. Riley Nelson and other collaborators, Dr. Sonja Scheffer reports that in the DNA barcodes for 500 individuals from the mountain, collected by the Nelson lab from 2000 to 2008, there are likely over 100 species previously unidentified in Utah, many undescribed. These flies are sensitive to temperature changes, requiring 95 degree days on average before emergence. The varied temperature regimes along American Fork Canyon therefore create an ideal study of their life cycle (Petitt et al 1991). Thus a study of Agromyzidae collected at different elevations along American Fork Canyon will provide both a way to discover the effect of temperature on different species and which species are present.

Agromyzidae can be both monophagous and polyphagous, i.e. feeding on one host or feeding on many different hosts, depending on the species. The larvae are destructive to their host plants, so knowledge of these hosts will not only add to our understanding of Agromyzidae life history it will also inform us of the influence they have on other plants and thereby their environment (Spencer 1987). By identifying these fly species and their suspected host plants, much basic biological information for these flies in Utah can be obtained. My goal was to collect more Agromyzidae to assist in identifying new species, to begin associating fly species with host plants, and correlate fly diversity with elevation, temperature, and other abiotic factors.

Materials and Methods

I conducted my research along the American Fork River up American Fork canyon. Four sites were chosen that have been previously used by Dr. Nelson and his students. Taking care that the malaise traps would not be easily visible to passerby’s we set the traps up near the river. From May 12 to May 19 snow blocked our access to the fourth site so we only have data from the lower three. All four sites were used from May 19 to June 9 however. Once the malaise traps were set up I returned every week to switch the Nalgene bottles and collect last week’s samples. Each sample was condensed into a 500 mL vial and stored in Dr. Nelson’s fridge to preserve the DNA quality. I collected samples from May 12 to June 9.

Starting September of 2015 I sorted the samples for Agromyzidae. I included Phoridae, Chloropidae and Ephydridae in my sorting as these families share the most similarities to Agromyzidae. I trained a student from Dr. Nelson’s lab to help me sort for Agromyzidae as well.

I also better organized some of the samples from the earlier studies in the Nelson lab so I could sort them more readily and compare them to the Scheffer work in progress.

Results

The number of Agromyzidae collected over four weeks is shown in Table 1. All four sites are up American Fork Canyon on Highway 92. Site one is located 0.5 mi east of the canyon mouth with coordinates N 40.43329˚ W111.73836˚ and elevation 1547m. Site two is near Hanging Rock down canyon from Little Mill Campground with coordinates N 40.44749˚ W111.68305˚ and elevation 1818 m. Site three is on the South Fork of American Fork River above the South Fork Ranger Station with coordinates N 40.45180˚ W 111.65754˚ and elevation 1862m. Site four is also on the South Fork of American Fork River near Timpooneke Guard Station with coordinates N 40.43226˚ W 111.63741˚ and elevation 2213 m.

Table 2 provides the degree days above 10˚C from 2005, 2006, 2007, 2008 and 2015. This provides a comparison between current and previous collections (Weather Data Depot).

Discussion

My collections were not able to collect as many Agromyzidae as needed to assist in identifying all the potential unidentified species found by Scheffer (Table 1). This could be for several reasons. I was not able to continue my collection throughout the entire summer, and it is possible that later in the summer would have found more success. Dr. Nelson collected malaise samples from the same locations in the summers of 2005, 2006, 2007 and 2008. Agromyzidae have largely been sorted out of the sample from 2007 and given to Dr. Scheffer for identification. I hope to continue sorting through the rest of the samples to compare and create a life history sketch for Agromyzidae.

Another potential cause of the reduced Agromyzidae samples is that spring and summer of 2015 did not follow the typical temperature patterns (Table 2). As Agromyzidae require 95 degree days to emerge, their low density in spring of 2015 could be due to the lowered temperature. Again, sorting the rest of the samples will provide more conclusive data to test this hypothesis.

I hope to also add to our knowledge of Agromyzidae host plants by collecting samples of Agromyzidae larvae and raising them. This will allow us to document the host plants of each species, which is currently unknown. Despite the knowledge that has been gained of Agromyzidae, my research unveils the need for further research and documentation of this unique family.

Citations

• Petitt, F., Allen, J., Barfield, C. 1991.“Degree-Day Model for Vegetable Leafminer (Diptera: Agromyzidae) Phylogeny.” Environmental Entomology.20:1134-1120.
• Spencer, KA. 1987. Agromyzidae. – In: McAlpine, J.F. &Peterson, B.V. & Shewell, G.E. & Teskey, H.J. & Vockeroth, J.R. & Wood, D.M. (Eds.): Manual of Nearctic Diptera. Volume 1. Research Branch, Agriculture Canada, Monographs 28: 869-880: Ottawa.
• Weather Data Depot. 2015. Energy Cap Inc. www.weatherdatadepot.com/