Starving honey bee (Apis mellifera) larvae signal pheromonally to worker bees.

Xu Jiang He,Wu Jun Jiang,Jian Hui Zhang,Xue Chuan Zhang,Zhi Jiang Zeng,Andrew B Barron

doi:10.1038/srep22359

Xu Jiang He, Wu Jun Jiang + Show 4 more

Open Access

https://doi.org/10.1038/srep22359

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Abstract

Cooperative brood care is diagnostic of animal societies. This is particularly true for the advanced social insects, and the honey bee is the best understood of the insect societies. A brood pheromone signaling the presence of larvae in a bee colony has been characterised and well studied, but here we explored whether honey bee larvae actively signal their food needs pheromonally to workers. We show that starving honey bee larvae signal to workers via increased production of the volatile pheromone E-β-ocimene. Analysis of volatile pheromones produced by food-deprived and fed larvae with gas chromatography-mass spectrometry showed that starving larvae produced more E-β-ocimene. Behavioural analyses showed that adding E-β-ocimene to empty cells increased the number of worker visits to those cells, and similarly adding E-β-ocimene to larvae increased worker visitation rate to the larvae. RNA-seq and qRT-PCR analysis identified 3 genes in the E-β-ocimene biosynthetic pathway that were upregulated in larvae following 30 minutes of starvation, and these genes also upregulated in 2-day old larvae compared to 4-day old larvae (2-day old larvae produce the most E-β-ocimene). This identifies a pheromonal mechanism by which brood can beg for food from workers to influence the allocation of resources within the colony.

Highlights

Communication between parents and young offspring for food provisioning presents an area of potential conflict between the amount of food requested by young and the optimal resource allocation by the parents
E-β-ocimene was the only chemical which was significantly higher in all starved larvae groups (SL) compared to the respective fed larvae groups (FL) (Fig. 2, Fig. S1), suggesting that it might be the candidate for the larval hunger signal
Our results have shown that food deprivation increased the amount of the volatile chemical E-β-ocimene produced by worker larvae (Fig. 2), and that 2-day old larvae, which are highly susceptible to starvation, produced more E-β-ocimene than 4-day old larvae

Summary

Introduction

Communication between parents and young offspring for food provisioning presents an area of potential conflict between the amount of food requested by young and the optimal resource allocation by the parents. Environmental factors influence the degree of parent-offspring conflict: for instance, a shortage of food could reduce the honesty of begging signals and increase sibling scramble competition[4]; Adding unrelated broodmates increases barn swallow chicks’ begging intensity[8]. These influential studies of parent-offspring conflict in mammals and birds illustrate the potential complexity of communication over resource allocation. Our findings suggest that a volatile component of brood pheromone, E-β-ocimene, is a candidate begging signal for young honey bee larvae It is actively synthesized by hungry larvae and attracts workers to inspect cells

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Results

Conclusion