Land-use and climate drive shifts in Bombus assemblage composition

Study Extent

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Sampling

Pest monitoring traps were placed along the margin of corn and alfalfa fields across a gradient of agriculturally intensified land in lower elevation areas (874 –1418 m) throughout five counties in northern and central Utah from 2014 to 2019 (Fig. 1) as part of early-detection surveys for invasive lepidopterans following Spears et al. (2016) and U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Cooperative Agricultural Pest Survey approved methods (CAPS, 2019). Six agricultural sites were surveyed within each county ((3 corn + 3 alfalfa fields)  5 counties, n = 30). Three multi-colored (green canopy, yellow funnel, and white bucket) bucket traps (International Pheromone Systems, Cheshire, UK) were spaced 20 m apart and hung 1.5 m above the ground along the field margin of each agricultural site (N = 540; 3 traps  30 sites  6 years). The three traps corresponded to the following target pests: cotton cutworm (CC, Spodoptera litura F.), Egyptian cotton leafworm (ECL, Spodoptera littoralis Boisduval), and Old World bollworm (OWB, Helicoverpa armigera Hübner). A single pheromone lure was placed inside the lure basket of the trap canopy. An insecticide strip (Hercon Vaportape II: 10% dimethyl 2,2-dichlorovinyl phosphate, Hercon Environmental Corporation, Emigsville, PA) and a small cellulose sponge were placed inside each bucket to kill the captured insects and absorb rainwater, respectively. Insecticide strips and pheromone lures for OWB were replaced every 28 days, while the pheromone lures for CC and ECL were changed every 84 days, following USDA APHIS CAPS survey protocols.

Method steps

1. Trap contents were collected every other week from late April to mid-September from 2014 to 2019. Since lure comparisons were not the intent of this study (but see Spears et al., 2016), trap data were combined by agricultural site and collection period. At the lab, trap contents were screened for target pests, and Bombus collected as bycatch were separated from all other specimens and then stored in a freezer at -18˚C until they could be pin-mounted, labeled, and identified to species using taxonomic keys (Koch et al., 2012; Williams et al., 2014).

Utah Bombus

1. Bombus
   rank: genus

Utah Landscape and Bombus assemblage