New work by Amy Toth and her lab:

Correlates of Worker Longevity—Colony Size. 

We found a significant negative association between mean colony size and mean worker 
longevity. Although there is substantial variation and colony size is not a perfect predictor 
of worker longevity, the fact that we found a significant relationship is noteworthy.

These data also fit well with
the disposable soma (i.e. "disposable caste") idea that colonies should reduce
investment in maintenance and lifespan of non-reproductive members with high
extrinsic mortality, and this effect should be most pronounced in species with large colonies.

Patterns of longevity across a sociality gradient in vespid wasps
Authors: Amy L. Toth, Seirian Sumner, Robert L. Jeanne
For: Special Issue of Current Opinion in Insect Science on "Ageing and the reversal of the fecundity/longevity trade-off in social insects"

They refer to a previous study:

We found that worker and queen lifespan diverge (increasing lifespan ratio) with increasing colony size in eusocial Hymenoptera. In honey bees (Apis mellifera) the same pattern is observed throughout colony growth: in small colonies workers have longer lives when compared with workers living in larger colonies. 

Increasing colony size leads to a number of social consequences: the reproductive potential of workers decreases while the social complexity and the degree of caste differentiation increase. Lifespan as a life-history trait appears to be affected by those changes.

As colony size increases the quality of individuals diverges and lifespan as an outcome of maintenance investments may be evolutionarily shaped to optimize productivity and hence fitness on the colony level by modifying the resource allocation into different castes. 

Kramer, B. H., & Schaible, R. (2013). Colony size explains the lifespan differences between queens and workers in eusocial Hymenoptera. Biological Journal of the Linnean Society, 109(3), 710-724.

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