Bumble Bees (Hymenoptera: Apidae) Respond to Moth (Lepidoptera: Noctuidae) Pheromone Components, Leading to Bee Bycatch in Monitoring Traps Targeting Moth Pests

Abstract

Semiochemical-baited traps are commonly used to monitor moth pests and inform management decisions. Unfortunately, bee pollinators can be unintentionally captured, which reduces monitoring system efficiency and may negatively impact pollinator biodiversity and pollination services. We assessed the abundance and diversity of wild bees captured in semiochemical-baited traps designed to capture cutworm and armyworm (Lepidoptera: Noctuidae) pests in North America. Green Unitraps were baited with semiochemicals including: (1) species-specific noctuid pheromone lures; (2) food bait lures consisting of fermentation by-products; or (3) floral volatiles. Traps were positioned in canola (Brassica napus L.) and wheat (Triticum aestivum L.) fields in Alberta, Canada. We also explored the mechanisms of bee detection of moth pheromone components using electroantennogram (EAG) assays to assess the antennal response of two Bombus species. We found that more bumble bees (Hymenoptera: Apidae), and especially Bombus rufocinctus Cresson, were captured in traps baited with moth pheromone lures than in unbaited control traps. Fermentation by-product lures captured a similar low number of bees as unbaited traps, whereas floral volatile-based food bait lures captured more bees, comparable to capture in pheromone-baited traps. In general, more Bombus spp. were captured in traps positioned at canola vs. wheat fields, but the community composition was similar among crops. EAG assays indicate that sensory receptors on the antennae of B. rufocinctus Cresson and B. impatiens Cresson detect noctuid moth pheromones. Perception of chemical signals of a different insect order may be explained by structural similarities in pheromone components produced by both moths and bumble bees.

Fermented or Floral? Developing a Generalized Food Bait Lure to Monitor Cutworm and Armyworm Moths (Lepidoptera: Noctuidae) in Field Crops

“…Traps baited with food bait lures based on fermented by-products had a low pollinator by-catch; however, the addition of a floral volatile increased Bombus spp. by-catch [ 17 ]. Food bait lures based on microbial volatile organic compounds may be especially suitable for monitoring cutworm and armyworm moths because pollinators do not appear to be attracted to these compounds.…”

“…In conclusion, food bait lures based on microbial volatile organic compounds can be further developed to attract redbacked cutworm moths and potentially other cutworm and armyworm pests in field crops, and have a minimum negative effect on native pollinator by-catch [ 17 ]. Although food bait lures capture lower numbers of targeted moths compared to sex pheromone-baited traps, both males and females of multiple cutworm species are attracted to AAMB lure.…”

“…(Apidae) and leaf-cutter bees (Megachilidae); and (2) vespids (Vespidae), which grouped the bald-faced hornet ( Dolichovespula maculata L.), the blackjacket ( Vespula consobrina Saussure) and the common aerial yellowjacket ( D. arenaria Fabricius). Results from pollinator by-catch in traps baited with lures for monitoring noctuid pest species were reported by Grocock et al [ 17 ], and thus, they are omitted from the results and discussion of this manuscript.…”

“…Furthermore, pheromone-based monitoring programs require individual traps for each species, which makes monitoring several pests costly and time consuming. Lastly, there is evidence for pollinator by-catch in lepidopteran sex pheromone-baited traps [ 17 , 18 , 19 , 20 ]. There are no reliable tools to monitor variation in density of most cutworm adult pest species in the Canadian Prairies.…”

Bumble Bee Responses to Climate and Landscapes: Investigating Habitat Associations and Species Assemblages Across Geographic Regions in the United States of America

“…Bumble bees were collected within pest monitoring traps that were placed by state cooperators in agricultural fields across diverse regions in the USA 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 for pest surveillance (CAPS, 2022). Previous research identified that bumble bees are attracted to pest monitoring traps and suggested that these captures be used to advance knowledge of biodiversity, population fluctuations, and other ecological objectives (Buchholz et al, 2011; Spears and Ramirez, 2015; Sipolski et al, 2019; Whitfield et al, 2019; Grocock et al, 2020; Grocock and Evenden, 2020; Parys et al, 2021; Spears et al, 2016, 2021; Christman et al, 2022a).…”