Adding essential oils to emergence tents has taxon-specific effects on trapping efficiency of ground-nesting bees

Abstract

Soil emergence tents (e-tents) are a new tool for studying the nesting biology of ground-nesting bees. Etents allow us to link nests with specific soil conditions; however, low success probabilities (≤ 20% of e-tents capture at least one bee) and long deployment times (> 72 h) limit their efficiency. We examined if adding scents-spearmint and lemongrass essential oils-increases how quickly e-tents capture bees actively nesting in the soil directly covered by the trap ("capture rate"), letting e-tents be moved more frequently to sample more area. Adding essential oils did not have a significant effect on the overall capture rate. However, in e-tents with spearmint essential oil, bees in the family Halictidae were captured 1.80× faster, and there was a trend for reduced capture rate for the family Andrenidae. The efficacy of adding scents to e-tents appears to be taxon-specific. Researchers interested in halictid nesting biology may increase the efficacy of e-tents with spearmint essential oil, but further work is needed to find a suitable attractant for other groups or whole communities.

Methods for interpreting emergence trap specimen data for the study of ground nesting bees (Hymenoptera: Anthophila)

“…Because the most common design of emergence traps is a tent that funnels bees into a collection container at the top, it's possible that some bees never make it up into the collection container. This is supported by research showing that it can take multiple days for bees in an emergence trap to actually be collected (Pane and Harmon-Threatt 2017, Grommes et al 2021). Further, given the differences of behavior between different species caught in an insect net (e.g.…”

“…Key point 5: It can take multiple days for a bee to be collected in an emergence trap It's important to note that it can potentially take multiple days for actively nesting bees to be collected in emergence traps (Grommes et al 2021). As a result, traps should be left in one spot for a few days to fully catch all nesting bees.…”