Odorant cues linked to social immunity induce lateralized antenna stimulation in honey bees (Apis mellifera L.)

Collins

Foster

2017

Preprint

Self Cite

In 2017, we published the paper "Odorant cues linked to social immunity induce lateralized antennal stimulation in honey bees (Apis mellifera L.)" in Scientific Reports. Since then, we have performed three follow-up experiments which have either negative or contradictory results. Previously, we used electrophysiology to show that hygienic bees displayed significantly higher sensitivity to β-ocimene when stimulated via their left antennae compared to their right. We repeated this assay using worker honey bees from a single hygienic colony and found, to our surprise, that the right antennae elicited higher sensitivity. We also previously attempted to identify a molecular basis for lateralization by using mass spectrometry-based proteomics to compare left and right antennal proteomes. Of the 1,845 proteins, none were differentially expressed. Here, we repeated this experiment but employed orthogonal peptide fractionation to increase proteome coverage to 3,114 proteins; however, still none were differentially expressed. Finally, we attempted to manipulate gene expression of a key antennal odorant binding protein linked to hygienic behaviour (OBP18) using RNA interference via antenna microinjection. We were not able to achieve long-lasting OBP18 knock-down, but comparing the proteomes of untreated, mock dsRNA-treated and OBP18 dsRNA-treated worker antennae revealed numerous off-target effects of the act of injecting alone. By openly reporting this data, we hope to set an example for information transparency.

Section: Introductioncontrasting

confidence: 55%

Results of follow-up experiments to “Odorant cues linked to social immunity induce lateralized antennal stimulation in honey bees (Apis mellifera L.)”

Collins

Foster

2017

Preprint

Self Cite

“…Protein was extracted by homogenizing each mite stage with ceramic beads as previously described ( 31 ). Clarified lysate was precipitated overnight with four volumes of 100% ice cold acetone, and the pellet was washed twice with ice cold 80% acetone.…”

Section: Methodsmentioning

confidence: 99%

“…For the sexual differentiation analysis, which excluded egg and protonymph stages, this was not the case, so missing values were imputed (width = 0.3, downshift = 1.5) to capture sex-specific proteins as previously described ( 36 ). Differential expression analysis across developmental stages was performed as previously described ( 31 ) except Perseus v1.5.6.0 was used, missing values were not imputed, and the ANOVA (one factor, seven levels) p values were Benjamini Hochberg-corrected at 5% FDR. For the analysis of sexually regulated genes, the female (deutonymph, adult daughter, and foundress) and male (deutonymph, adult son) samples were pooled as n = 9 and n = 6, respectively.…”

Section: Methodsmentioning

confidence: 99%

A Varroa destructor protein atlas reveals molecular underpinnings of developmental transitions and sexual differentiation

Molecular & Cellular Proteomics

Chan

Evans

et al. 2017

Self Cite

Varroa destructor is the most economically damaging honey bee pest, weakening colonies by simultaneously parasitizing bees and transmitting harmful viruses. Despite these impacts on honey bee health, surprisingly little is known about its fundamental molecular biology. Here, we present a Varroa protein atlas crossing all major developmental stages (egg, protonymph, deutonymph, and adult) for both male and female mites as a web-based interactive tool (http://foster.nce.ubc.ca/varroa/index.html). We used intensity-based label-free quantitation to find 1,433 differentially expressed proteins across developmental stages. Enzymes for processing carbohydrates and amino acids were among many of these differences as well as proteins involved in cuticle formation. Lipid transport involving vitellogenin was the most significantly enriched biological process in the foundress (reproductive female) and young mites. In addition, we found that 101 proteins were sexually regulated and functional enrichment analysis suggests that chromatin remodeling may be a key feature of sex determination. In a proteogenomic effort, we identified 519 protein-coding regions, 301 of which were supported by two or more peptides and 169 of which were differentially expressed. Overall, this work provides a first-of-its-kind interrogation of the patterns of protein expression that govern the Varroa life cycle and the tools we have developed will support further research on this threatening honey bee pest.

“…Previously, we compared odorant profiles of freeze-killed pupae and healthy pupae to find candidate hygienic behavior-inducing compounds 40 . Although freeze-killing is not a natural means of death, it is a relevant system because the freeze-killed brood assay 41 is the main method for determining colonies’ level of hygiene.…”

Section: Introductionmentioning

confidence: 99%

“…The queen also produces β-ocimene, which also contributes to inhibiting worker egg-laying 47 . Prior to our work in 2017 40 , β-ocimene and oleic acid had not been linked to hygienic behavior in honey bees.…”

Section: Introductionmentioning

confidence: 99%

A death pheromone, oleic acid, triggers hygienic behavior in honey bees (Apis mellifera L.)

Chapman

Iovinella

et al. 2018

Sci Rep

Self Cite

Eusocial insects live in teeming societies with thousands of their kin. In this crowded environment, workers combat disease by removing or burying their dead or diseased nestmates. For honey bees, we found that hygienic brood-removal behavior is triggered by two odorants – β-ocimene and oleic acid – which are released from brood upon freeze-killing. β-ocimene is a co-opted pheromone that normally signals larval food-begging, whereas oleic acid is a conserved necromone across arthropod taxa. Interestingly, the odorant blend can induce hygienic behavior more consistently than either odorant alone. We suggest that the volatile β-ocimene flags hygienic workers’ attention, while oleic acid is the death cue, triggering removal. Bees with high hygienicity detect and remove brood with these odorants faster than bees with low hygienicity, and both molecules are strong ligands for hygienic behavior-associated odorant binding proteins (OBP16 and OBP18). Odorants that induce low levels of hygienic behavior, however, are weak ligands for these OBPs. We are therefore beginning to paint a picture of the molecular mechanism behind this complex behavior, using odorants associated with freeze-killed brood as a model.