Cerceris fumipennis Say, 1837 (Hymenoptera: Crabronidae) is a wasp that provisions its subterranean nests with jewel beetles (Coleoptera: Buprestidae). At 3 newly discovered colonies in British Columbia (BC), C. fumipennis prey were collected by excavating the subterranean nests, using sweep nets to capture paralyzed prey in the grasp of a female returning to her nest, or collecting prey discarded at the nest entrance. In total, 9 species were collected: Acmaeodera idahoensis Barr, Agrilus crataegi Frost, Agrilus granulatus populi Fisher, Anthaxia (Haplanthaxia) caseyi caseyi Obenberger, Chrysobothris laricis Van Dyke, Chrysobothris leechi Barr, Phaenops drummondi (Kirby), Phaenops gentilis (LeConte) and Phaenops intrusa (Horn). Anthaxia caseyi caseyi was the smallest beetle (4.2 mm) while C. leechi was the largest (12.0 mm). The average size of all buprestid prey taken by females from all 3 colonies was 8.8 mm. These represent the first prey records for C. fumipennis in BC and with the exception of P. drummondi are new prey records for this wasp. A single Harpalus affinis (Schrank) (Coleoptera: Carabidae) was discovered within a brood cell containing Acmaeodera spp. elytra, but it is unclear if this beetle was placed in the cell by a female wasp.

Cerceris fumipennis , Hymenoptera , Crabronidae , biosurveillance, pest detection

Cerceris fumipennis Say, 1837 (Hymenoptera: Crabronidae) is a ground-nesting wasp in which females provision their nests with paralysed buprestid beetles in jelly bean shaped subterranean cells (Scullen 1965; Hook and Evans 1991; Marshall et al. 2005). In Canada, colonies have been discovered in western Québec and throughout southern Ontario (Buck 2004; Marshall et al. 2005; Careless et al. 2009; Careless 2010). In 2012 and 2013, a total of 1 male and 4 females were captured by sweep net at a colony in Merritt, British Columbia (BC) (Kimoto and Buck 2015). This represents the first time C. fumipennis has been recorded from BC since 1935 (2 females collected by R.H. Beamer on 3 August 1935; University of Kansas Natural History Museum, Lawrence, Kansas, US) and also represents the first recorded colony.

Female Cerceris fumipennis are adept at capturing a wide variety of buprestid beetles, and have been the source for various new provincial, state and national records (Marshall et al. 2005). Therefore, it has been used in eastern North America by the Canadian Food Inspection Agency (CFIA) and other departments as a biosurveillance tool to detect the non-indigenous emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) (Marshall et al. 2006; Careless et al. 2009; Nalepa et al. 2012; Careless et al. 2014). In the eastern US, citizen-scientist programs have been established whereby colonies are “adopted” and monitored by the public. In 2012, an adopted C. fumipennis colony was responsible for the first state record of emerald ash borer in Connecticut (Rutledge et al. 2013). It is the intention of the senior author to establish citizen-scientist programs in BC to detect non-indigenous buprestid beetles, but additional colonies need to be discovered before this can occur.

In 2013 and 2014, additional sites from the Greater Vancouver Region, the Fraser Canyon, and the Okanagan Valley were examined for the presence of Cerceris fumipennis colonies. This paper outlines the variety of sites examined, the location of two new colonies and first prey records for C. fumipennis in BC.

Lytton and Lillooet represent 2 newly discovered Cerceris fumipennis colonies in BC. Eleven other species of wasps, including C. nigrescens, were collected at the Merritt, Lillooet and Lytton colonies; yet C. californica was not among them. A tremendous amount of time and resources were used to examine multiple sites from 2012 to 2014, yet only 3 C. fumipennis colonies have been discovered, resulting in a 3% success rate. Compared to a 22% success rate in finding C. fumipennis colonies in Connecticut, North Carolina and Maine (Nalepa et al. 2012), it appears that colonies are less common in BC. The northernmost colony in Ontario is in Parry Sound District (MacDougall Public School, 45.39861°N) (P.D. Careless, personal observation) which is substantially further south than all 3 BC colonies. Lillooet (50.67669°N) represents the most northern North American colony to date. The annual number of degree days above 5 °C in Lillooet is 2387.8 compared to 1702.4 in Beatrice, ON, which is the weather station closest to Parry Sound (Anonymous 2015). As colonies can occur at sites in Ontario that are cooler than Lillooet, there may be additional colonies further north in BC.

Unlike Cerceris californica in Washington state (Looney et al. 2014) or C. fumipennis in eastern North America (Nalepa et al. 2012; Careless et al. 2014), none of the BC colonies were discovered in baseball fields. Most baseball fields in southwestern BC are comprised of red shale containing many rock fragments which is likely a poor nesting substrate for C. fumipennis (Fig. 5). All 3 colonies occur within compact sand parking lots (Lytton and Lillooet) or compact silt pathways (Merritt) with full sun exposure throughout the day (Figs 1, 2). The colonies occur in the 2 biogeoclimatic zones, Bunchgrass and Ponderosa Pine, with the warmest and driest summers in BC. The Bunchgrass zone is generally characterized by widely spaced Pseudoroegneria spicata (Pursh) Á. Löve (bluebunch wheatgrass) and Artemisia tridentata Nuttall (big sagebrush) although ponderosa pine and Douglas-fir, Pseudotsuga menziesii (Mirbel) Franco (Pinaceae), also occur in this zone. The Ponderosa Pine zone consists of very open, park-like stands of ponderosa pine with an understory of bluebunch wheatgrass (Anonymous 2007). Both zones have a sparse distribution of trees, allowing many areas to receive full sun throughout many summer days. The nesting areas in Merritt and Lytton both occur on a slight incline that assists in drainage. There is very little similarity in soils between the 3 sites. Merritt is predominantly silt (66.6%) and has the largest component of clay at 21.8%. Lytton is primarily sand (80.9%), and Lillooet is 59.6% sand and 34.1% silt. Further analysis is required to determine if there are specific constituents required for nesting or if there are other factors that play a more significant influence in nest site selection. Three additional sites in Merritt with suspect Cerceris entrance holes were excavated, but Cerceris nests were not present and the substrate consisted of substantially more and larger pebbles.

Figure 5. 

Red shale typically found in baseball fields in southwestern BC. Note 2 ant nests.

Recently, archived Cerceris fumipennis specimens have been discovered in the WallisRoughley Museum (University of Manitoba) and the Strickland Museum (University of Alberta). These specimens were collected in Spruce Woods Provincial Park, MB and Writing-on-Stone Provincial Park, AB and resemble the eastern race of C. fumipennis in size and colouration. Both sites are further south than the Lillooet colony. Perhaps Cerceris fumipennis is more cold tolerant than C. californica, thus explaining its distribution within many of Canada’s provinces whereas the latter occurs in western North America where winters are relatively short and mild.

A total of 9 buprestid species were collected at the 3 Cerceris fumipennis colonies. Chrysobothris leechi was the most common intact beetle collected, followed by Phaenops drummondi, Agrilus granulatus populi, Anthaxia caseyi caseyi, and P. gentilis. Single specimens of A. crataegi, P. intrusa, C. laricis and Acmaeodera idahoensis were also found at these C. fumipennis colonies. During nest excavation, buprestid-filled C. fumipennis cells occurred between 10 and 20 cm below the surface which is similar to nests in eastern North America (Careless et al. 2009). Since wasp larvae feed on paralyzed prey, body parts were collected more often than intact beetles during nest excavation thereby making species-level identification difficult if not impossible. Many Chrysobothris, Anthaxia and Acmaeodera elytra were found in the cells which could alter the actual ratio of species preyed upon by C. fumipennis. Population size, predatory avoidance behaviour, size of the beetle, and other factors will affect whether or not a beetle is suitable prey for C. fumipennis.

The size of Cerceris fumipennis prey ranged from 4.2 mm (Anthaxia caseyi caseyi) to 12.0 mm (Chrysobothris leechi). Chrysobothris leechi was not only the most common intact beetle collected, but on average it was the largest species at 10.5 mm. In comparison, Phaenops intrusa comprised over 70% of the prey taken by Cerceris californica Cresson in southcentral Washington (Looney et al. 2014). In New York State, C. fumipennis captured prey ranging in size from 4.1 to 18.9 mm (Hellman and Fierke 2014); the latter is 57% larger than the C. leechi found at the Merritt colony. Buprestis aurulenta (Linnaeus) is a relatively common and large buprestid (12–20 mm) occurring in southern BC that breeds within Douglas-fir and ponderosa pine (Furniss and Carolin 1977), yet it was not collected at any of the C. fumipennis colonies. Although only a handful of C. fumipennis specimens have been collected in BC, females appear to be within the lower size range (wing length 9.5–10.5 mm; n = 6) of their eastern counterparts (wing length 9.5–13.5 mm; n = 75) (Kimoto and Buck 2015). There is a positive linear relationship between the size of Cerceris arenaria L. and C. halone Banks with the size of the prey weevils collected (Byers 1978; Polidori et al. 2005). The smaller size C. fumipennis from BC has likely contributed to the smaller prey items captured by provisioning females.

All of these beetles represent the first prey records for Cerceris fumipennis in BC. Phaenops drummondi is a known prey of eastern C. fumipennis (Paiero et al. 2012); however, all the other species and subspecies (i.e. Agrilus granulatus populi) are new prey records for this wasp. Agrilus granulatus populi and P. intrusa are also prey of C. californica in Washington state (Looney et al. 2014). Based on the list of prey species it is almost certain that female C. fumipennis forage on shrubs, conifers, deciduous trees and possibly flowers in BC (Table 5).

One ground beetle, Harpalus affinis was collected in a cell at 15.23 cm below grade along with the elytra of Acmaeodera spp. As other carabids were not discovered anywhere else in the nest it is uncertain if Cerceris fumipennis intentionally captured and provisioned the cell with this beetle. In 2009 and 2010, female C. fumipennis in Connecticut, Maine and New York captured 3 chrysomelids, Neochlamisus bebbianae (Brown), Bassareus mammifer (Newman), Leptinotarsa decemlineata (Say); 1 scarab, Popillia japonica Newman; and 2 cerambycids, Saperda discoidea F., Oberea schaumiiLeConte (Rutledge et al. 2011). Neochlamisus bebbianae, B. mammifer and P. japonica are shiny and similar in appearance to many jewel beetles, while S. discoidea and O. schaumii occur in tree canopies where C. fumipennis will forage. Therefore, collection of these non-prey items is understandable. Harpalus affinis is similar in length to some buprestids, however it looks different than most jewel beetles. Although adult H. affinis can fly, this specimen may have wandered into the nest entrance searching for prey or shelter. Until female wasps are intercepted carrying H. affinis back to their nests, this species can not be considered a prey item of C. fumipennis.

Despite a significant amount of time spent searching many sites, only 3 Cerceris fumipennis colonies have so far been discovered in BC; they seem to be less common than colonies in eastern North America. A total of 9 buprestid species are recorded here as prey items of BC C. fumipennis and with the exception of P. drummondi, are all new prey records for this wasp. The prey ranged in size from 4.2 to 12.0 mm and seem to be smaller than prey collected by eastern wasps. Cerceris fumipennis in BC appear to be smaller than specimens occurring east of the Rocky Mountains which may contribute to the difference in size of prey collected.

Tyler Kimoto assisted in excavating the Central Park, Merritt colony. Jeffrey Jarret (CFIA) identified Harpalus affinis. Darrell Finnigan, City of Merritt, provided permission to excavate the Central Park colony. Lee Humble, Natural Resources Canada – Canadian Forest Service, assisted in measuring buprestids. Mireille Marcotte, Robert Favrin and Wendy Laviolette, CFIA, provided financial and administrative support to conduct field work. Jacob Kanyaya, CFIA, generated the maps. Clive Dawson and Anette LaJeunesse, British Columbia Ministry of Environment, conducted soil analysis.