Queen-produced volatiles change dynamically during reproductive swarming and are associated with changes in honey bee (Apis mellifera) worker behavior

International audienceAbstractDuring colony fission, honey bee workers are exquisitely sensitive to the presence of their queen in airborne swarms and bivouacs and will abandon swarming if she is absent. However, it is not known whether swarming queens produce a chemical bouquet that is distinct from non-swarming queens, containing either unique chemicals or altered proportions of chemicals. We found that queens emitted higher quantities and greater numbers of unique volatiles at liftoff than they did prior to swarming or in clustered bivouacs, and swarming workers tended to be attracted to these liftoff volatile blends. Pentadecane and heptadecane were collected most frequently and emitted in significantly higher quantities by queens at liftoff; these compounds have been described as pheromone components in other social insects, but not yet in honey bees. Our results suggest that volatile emission by queens is more dynamic than previously thought and that changes in their chemical signals may play a role in regulating the behavior of swarming workers

Emerging Themes from the ESA Symposium Entitled “Pollinator Nutrition: Lessons from Bees at Individual to Landscape Levels”

Pollinator populations are declining (Biesmeijer et al., 2006; Brodschneider et al., 2018; Cameron et al., 2011; Goulson, Lye, & Darvill, 2008; Kulhanek et al., 2017; National Research Council, 2007; Oldroyd, 2007), and both anecdotal and experimental evidence suggest that limited access to high quality forage might play a role (Carvell, Meek, Pywell, Goulson, & Nowakowski, 2007; Deepa et al., 2017; Goulson, Nicholls, Botias, & Rotheray, 2015; Potts et al., 2003, 2010; Vanbergen & The Insect Pollinators Initiative, 2013; Vaudo, Tooker, Grozinger, & Patch, 2015; Woodard, 2017). Multiple researchers are earnestly addressing this topic in a diverse array of insect-pollinator systems. As research continues to be published, increased communication among scientists studying the topic of nutrition is essential for improving pollinator health

Effects of native prairie forbs on the foraging choices and recruitment behavior of honey bees (Apis mellifera)

University of Minnesota Ph.D. dissertation. 2020. Major: Entomology. Advisor: Marla Spivak. 1 computer file (PDF); xii, 154 pages + 4 folders of supplemental files.Recent increases in honey bee colony mortality have prompted many organizations to plant flowers to improve bee nutrition. However, there remain questions about which flower species to plant and how best to plant them. Honey bees and many non-native species of flowering plants arrived in North America with European colonists. To help restore diverse native species, many organizations would like to increase plantings of native flowers. In the Upper Midwest region, multiple organizations are working to reconstruct tallgrass prairie habitats, including native prairie forb species. However, it was unknown whether those species would attract and benefit honey bees. To inform future bee-friendly prairie planting projects, I conducted studies examining honey bee foraging choices. In Chapter 1, I gave honey bee colonies access to large, reconstructed prairies and recorded their recruitment behaviors (decoding and mapping waggle dance communications). I found that honey bee foragers mainly danced to advertise non-prairie flower patches and non-native flowers as profitable pollen sources, but seven native prairie taxa were also advertised as profitable pollen sources. At one site colonies became significantly more likely to advertise nectar sources in prairies in August/September. In Chapter 2, I gave honey bee colonies access to reconstructed prairies and concentrated plantings of native prairie species to further explore how access to prairies affects colony diet breadth. That study showed major contributions of non-native pollen sources, but colonies collected native prairie and native non-prairie sources as well, especially at the end of the season in most sites. The taxa most frequently collected tend to grow in dense patches, suggesting that planting density may have a strong effect on honey bee recruitment. In Chapter 3, I tested a recently-published method for mapping honey bee waggle dances using data collected during the study presented in Chapter 1. In Chapter 4, I used that new method to examine how the density of flowers in a patch affects honey bee recruitment behavior. This approach was novel as previous studies on recruitment used point-source sugar feeders. While my first attempt did not reveal significant preferences for more dense patches of flowers, it did highlight lessons for future experiments that manipulate variables at the flower patch level to better understand the factors that drive honey bee recruitment. Overall, these results provide insights into which species are most likely to attract honey bees to bee-friendly plantings in the Upper Midwest

Comparing reversal-learning abilities, sucrose responsiveness, and foraging experience in scout and non-scout honey bee (Apis mellifera) foragers

Honey bees (Apis mellifera) colonies divide foraging activities between scouts, who search for new sources of food, and non-scouts, who rely on information from waggle dances to find food sources. Molecular analyses of scouts and non-scouts have revealed differences in the expression of numerous genes, including several related to neurotransmitter signaling. Despite this progress, we know almost nothing about cognitive, sensory, or behavioral differences that underlie scouting. I tested three hypotheses related to differences between scouts and non-scouts. First, I hypothesized that scouts and non-scouts differ in their reversal-learning abilities. Scouts showed a significantly faster reversal in their response to an odor that was punished and then rewarded. The results also suggested an interaction between the effects of foraging role (scout or non-scout) and seasonal effects on reversal-learning abilities. Second, I hypothesized that variation in responsiveness to sucrose rewards is associated with scouting behavior. I found no significant difference in responsiveness between scouts and non-scouts. Third, I hypothesized that greater foraging experience increases the probability that a forager will engage in scouting behavior. I tested this by comparing wing damage between scouts and non-scouts and found that non-scouts showed greater wing damage in the early summer but not the late summer. Together, these three results contribute to our understanding of cognitive, sensory, and behavioral aspects associated with scouting behavior

Emerging Themes from the ESA Symposium Entitled “Pollinator Nutrition: Lessons from Bees at Individual to Landscape Levels”

Pollinator populations are declining (Biesmeijer et al., 2006; Brodschneider et al., 2018; Cameron et al., 2011; Goulson, Lye, & Darvill, 2008; Kulhanek et al., 2017; National Research Council, 2007; Oldroyd, 2007), and both anecdotal and experimental evidence suggest that limited access to high quality forage might play a role (Carvell, Meek, Pywell, Goulson, & Nowakowski, 2007; Deepa et al., 2017; Goulson, Nicholls, Botias, & Rotheray, 2015; Potts et al., 2003, 2010; Vanbergen & The Insect Pollinators Initiative, 2013; Vaudo, Tooker, Grozinger, & Patch, 2015; Woodard, 2017). Multiple researchers are earnestly addressing this topic in a diverse array of insect-pollinator systems. As research continues to be published, increased communication among scientists studying the topic of nutrition is essential for improving pollinator health

Characterization of Genomic Variants Associated with Scout and Recruit Behavioral Castes in Honey Bees Using Whole-Genome Sequencing

<div><p>Among forager honey bees, scouts seek new resources and return to the colony, enlisting recruits to collect these resources. Differentially expressed genes between these behaviors and genetic variability in scouting phenotypes have been reported. Whole-genome sequencing of 44 <i>Apis mellifera</i> scouts and recruits was undertaken to detect variants and further understand the genetic architecture underlying the behavioral differences between scouts and recruits. The median coverage depth in recruits and scouts was 10.01 and 10.7 X, respectively. Representation of bacterial species among the unmapped reads reflected a more diverse microbiome in scouts than recruits. Overall, 1,412,705 polymorphic positions were analyzed for associations with scouting behavior, and 212 significant (p-value < 0.0001) associations with scouting corresponding to 137 positions were detected. Most frequent putative transcription factor binding sites proximal to significant variants included Broad-complex 4, Broad-complex 1, Hunchback, and CF2-II. Three variants associated with scouting were located within coding regions of ncRNAs including one codon change (LOC102653644) and 2 frameshift indels (LOC102654879 and LOC102655256). Significant variants were also identified on the 5’UTR of membrin, and 3’UTRs of laccase 2 and diacylglycerol kinase theta. The 60 significant variants located within introns corresponded to 39 genes and most of these positions were > 1000 bp apart from each other. A number of these variants were mapped to ncRNA LOC100578102, solute carrier family 12 member 6-like gene, and LOC100576965 (meprin and TRAF-C homology domain containing gene). Functional categories represented among the genes corresponding to significant variants included: neuronal function, exoskeleton, immune response, salivary gland development, and enzymatic food processing. These categories offer a glimpse into the molecular support to the behaviors of scouts and recruits. The level of association between genomic variants and scouting behavior observed in this study may be linked to the honey bee’s genomic plasticity and fluidity of transition between castes.</p></div

Heat map depicting the correlation between genotypes across variants associated with scouting behavior located on LG5 (NC_007074.3); location in bp is denoted by the rightmost number and gray color indicates no genotypic variation among all bees within one behavior group.

<p>Heat map depicting the correlation between genotypes across variants associated with scouting behavior located on LG5 (NC_007074.3); location in bp is denoted by the rightmost number and gray color indicates no genotypic variation among all bees within one behavior group.</p

Heat map depicting the linear correlation between genotypes across the variants associated with scouting behavior located on LG12 (NC_007078.1); location in bp is denoted by the rightmost number and gray color indicates no genotypic variation among all bees within one behavior group.

<p>Heat map depicting the linear correlation between genotypes across the variants associated with scouting behavior located on LG12 (NC_007078.1); location in bp is denoted by the rightmost number and gray color indicates no genotypic variation among all bees within one behavior group.</p