Canadian Journal of Arthropod Identification
 
 

Orthoptera of Alaska: A photographic key, new records, and synonymy of Melanoplus gordonae

CJAI 44 -- April 23, 2021
doi:10.3752/cjai.2021.44

Adam Haberski, Derek A. Woller, and Derek S. Sikes

| Abstract | Introduction | Checklist | Materials & Methods | Taxonomy | DNA Barcoding | Species Key | Acknowledgments | References | PDF | Cite |
 
 

Introduction

Orthoptera (grasshoppers, crickets, and katydids) are among the most familiar and easily recognized insects. Orthopteran diversity is greatest in the tropics and decreases towards the poles. Alaska lies mostly above the 60th parallel where low temperatures and a short growing season act as strong filters to northward dispersal (Fielding 2004; Fielding and Defoliart, 2007; Kaufmann 2017). As such, of the 1,200 or so North American species, only 18 are known from Alaska (Table 1). The short-horned grasshoppers (Acrididae), dwarf grasshoppers (Tetrigidae), and camel crickets (Rhaphidophoridae) are represented, but the nocturnal-singing true crickets (Gryllidae) and katydids (Tettigoniidae) are conspicuously absent. Fifteen Alaskan species are shared with the 18 species that occur in the Yukon (Vickery 1997). The three not known from Alaska are Stethophyma lineatum (Scudder, 1862), Melanoplus packardii Scudder, 1878, and the Yukon-endemic Bruneria yukonensis Vickery, 1969. The last species has been collected less than 150 km from the Alaskan border, however, so Bruneria yukonensis may be present in eastern Alaska but has yet to be collected (Catling 2008). Rugged geography and limited road access have left much of the state, particularly the western half, under-sampled (Fig. 1).

Figure 1. Map of Orthoptera collection records in Alaska. The most thoroughly sampled localities are Palmer (1286 specimens), Denali National Park & Preserve (939), Prince of Wales Island (287), and Fairbanks (273). Numbers in colored circles correspond to specimen record counts and colors indicate orders of magnitude, with blue = 1-9, yellow 10-99, red 100-999, purple >1000.

Three species, Melanoplus sanguinipes (Fabricius, 1798), M. borealis (Fieber, 1853), and Camnula pellucida (Scudder, 1862), are significant agricultural pests (Pfadt 2002). Although normally in low abundance, they can reach outbreak levels when unusually warm summer temperatures enable rapid maturation (Washburn 1953). Alaska is warming faster than any other state, and we can expect outbreak conditions to be met more frequently as mean summer temperatures rise (Serreze et al. 2000; Walsh et al. 2008). For example, warming has already contributed to intensified outbreaks of spruce beetles (Dendroctonus rufipennis Kirby, 1837) on the Kenai Peninsula (Berg et al. 2006).

During the last glacial maximum, Interior Alaska formed part of an ice-free refugium known as Beringia. At this time, the Bering Land Bridge allowed for species exchange between ice-free Alaska and eastern Siberia, but ice sheets blocked dispersal to the rest of North America. Beringia was characterized by an open steppe grassland with no modern analogue (Young 1982). Habitat restrictions or low dispersal ability may have therefore prevented some species from spreading into deglaciated Canada at the end of the Pleistocene. This complex biogeographic history has led to intercontinental disjunctions and endemic species (e.g., Sikes et al. 2016). Catling (2008) listed three Alaskan species as having a Beringian distribution: Aeropedellus arcticus Hebard, 1935, Bohemanella frigida (Boheman, 1846), and Xanthippus brooksi Vickery, 1967.

At the start of our investigation, an additional species, M. gordonae Vickery, 1969, was recognized from Alaska. Melanoplus gordonae was known only from the type specimens collected near Fairbanks, Alaska, in 1969. Subsequent efforts to recollect it had failed, leading us to believe that it was either a rare endemic or, possibly, extinct. However, these assumptions were called into question when we examined unidentified Melanoplus specimens in the University of Alaska Museum (UAM) Insect Collection that exhibited some morphological traits characteristic of M. gordonae, but not the distinctly trilobate male subgenital plate described by Vickery (1969) as the primary distinguishing character of the species. These specimens did not key out cleanly to any known Alaskan species using existing keys for Alaska and Yukon, Canada (Vickery 1969; Vickery and Kevan 1985 (1986); Catling 2008). These findings prompted an investigation into the taxonomic status of M. gordonae, which is described herein.

Our goal was to review all available literature, specimen, and DNA barcode data to produce a complete and concise resource for identifying the known Alaskan Orthoptera. This key includes high-resolution color photographs of each species and all diagnostic characters, as well as updated species distribution maps. Synanthropic species that can only survive indoors in Alaska, such as Acheta domesticus (Linnaeus, 1758), are not included. We incorporated recent taxonomic changes as well as many new collection records.

A brief overview of Orthoptera research in Alaska

The earliest known Alaskan Orthoptera specimens were collected by Robert Kennicott, who, in 1860, descended the Yukon River as far west as Fort Yukon, Alaska (Foster 1913). He collected the state’s first records of Arphia conspersa Scudder, 1875, M. borealis, M. sanguinipes, and a new species named in his honor: M. kennicottii Scudder, 1878 (Scudder 1875, 1878, 1897). He returned to Alaska in 1865 but died unexpectedly in the spring of 1866 before he could collect more specimens (Schlachtmeyer 2010).

Collections were rare for the remainder of the 19th and early 20th centuries. In 1893, T.C. Mendenhall contributed three specimens of M. bruneri Scudder, 1897 to the U.S. National Museum while surveying the boundary between Alaska and Canada (Scudder 1897). In 1899, Trevor Kincaid, entomologist of the Harriman expedition, collected 14 individuals of M. borealis at Kukak Bay, the only Orthoptera among his 8,000 specimens (Caudell 1900). In 1912, J.M. Jessups of the Canadian Arctic Expedition collected B. frigida along the 69th parallel (Caudell 1915; Weber 1950), which was a new record for Alaska as well as the western hemisphere.

Grasshoppers have traditionally been overlooked by the general Alaskan public (perhaps due to limited abundance), so much so that they were “considered a novelty by many and in some areas of the state have been written up as a news story when noticed…” (Washburn 1965). This changed in 1951 when there was an outbreak of M. sanguinipes on agricultural lands near Butte, Alaska. Grasshopper densities reached an incredible 300 individuals per square yard (Washburn 1953). A subsequent outbreak in 1953 was only halted after a float plane sprayed crops with Aldrin, a now-banned insecticide. This was the first example of an airplane suppression program for agricultural pests in Alaska (Washburn 1965). Outbreaks of this and other species continued sporadically for several decades. In 1990, a fungal pathogen, “Entomophaga praxibuli,” was experimentally released as a biological control agent at two sites near Delta Junction, but the project was halted due to poor results and later concerns for non-target grasshopper species (Goodman 1993; Hostetter 1996-2000, Quarberg and Jahns 2002). The outbreaks ceased in 1992 when late spring and early autumn snow greatly reduced populations by interrupting lifecycles (Quarberg and Jahns 2002).

Alaska’s most prolific collector of Orthoptera was Richard Washburn. He collected over 1,200 specimens (now part of the UAM insect collection) during his 29 years at the Agricultural Experiment Station in Palmer, Alaska, from 1950-1979 (Murray 1979). Among his contributions were a detailed description of the life history of M. sanguinipes in Alaska and collection of the first state record of Tetrix subulata (Linnaeus, 1758) (Rehn 1952; Washburn 1965).

In recent decades, The University of Alaska Fairbanks and the U.S. Department of Agriculture have conducted extensive work on the physiology and ecology of sub-arctic Melanoplini (e.g., Fielding 2004; Fielding and Defoliart 2007; Zhang and Fielding 2011). The UAM has expanded its collection of Alaskan Orthoptera to over 3,000 specimens due to extensive sampling in Denali National Park & Preserve and on Prince of Wales Island (Fig. 1). The museum’s DNA barcoding efforts have also identified new state records and potential cryptic species (Sikes et al. 2017).