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Collins, T. F.

Publications and source records attributed to Collins, T. F..

3 recordsLinked to original sources

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

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 {beta}-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.

molecular biology

Death pheromones triggering hygienic behavior in honey bees (Apis mellifera L.)

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 - {beta}-ocimene and oleic acid - which are released from brood upon freeze-killing. {beta}-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 {beta}-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.

animal behavior and cognition

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

Hygienic behaviour (HB) is a social immunity trait in honey bees (Apis mellifera L.) whereby workers detect, uncap and remove unhealthy brood, improving disease resistance in the colony. This is clearly economically valuable; however, the molecular mechanism behind it is not well understood. The freeze-killed brood (FKB) assay is the conventional method of HB selection, so we compared odour profiles of FKB and live brood. Surprisingly, we found that significantly more brood pheromone ({beta}-ocimene) was released from FKB. {beta}-ocimene abundance also positively correlated with HB, suggesting there could be a brood effect contributing to overall hygiene. We found that β ocimene stimulated worker antennae in a dose-dependent manner, with the left antennae responding significantly stronger than right antennae in hygienic bees, but not in non-hygienic bees. This suggests that HB depends not only on odour detection, but also lateralization of sensitivity. We also compared odour profiles of Varroa-infested brood to healthy brood and found an overall interactive effect between developmental stage and infestation, but specific odours did not drive these differences. Overall, the data we present here is an important foundation on which to build our understanding the molecular mechanism behind this complex behaviour.

biochemistry