Fungicide Scent Pollution Disrupts Floral Search-and-Selection in the Bumblebee Bombus impatiens

Abstract

Bumblebees are valuable generalist pollinators. However, micro- and macro-stressors on bumblebees negatively impact both foraging efficiency and pollination efficacy. Given that colonies have a resource threshold for successful reproduction, factors that decrease foraging efficiency could negatively impact conservation efforts. Recently, agrochemical odor pollution has been shown to hinder floral odor learning and recognition in Bombus impatiens via an associative odor learning assay (FMPER). These results may have implications for the field foraging behavior of bumblebees. Building on this prior work, our study aimed to determine if negative effects of fungicides on associative odor learning and recognition scale up to negative impacts on actively foraging bumblebees. These experiments investigated whether the presence of a background fungicide odor (Reliant® Systemic Fungicide) impacts the location of a learned floral resource (lily of the valley-scented blue flowers) in a wind tunnel. Experiments were run with and without early access to visual cues to determine if fungicide odor pollution is more impactful on bees that are engaged in olfactory versus visual navigation. Fungicide odor pollution reduced landing frequency in both paradigms.

Behavioral state influences encoding mechanisms of color and odor integration in a model insect, the bumblebee Bombus impatiens

“…In addition, anthropogenic activity can indirectly impact sensory signals that are utilized by bumblebees while foraging for floral resources. For example, negative effects of human activity on floral-scent signaling and reception include a reduction of distance traveled by floral scent [6,7], increased foraging times [8], decreases in floral scent recognition [9][10][11][12], and alterations of flower visitation rates [13,14]. These negative effects are potentially exacerbated by asymmetric impacts of sublethal pesticide exposure with odor-learning,but not color-learning, being impaired [15].…”