The evolution of biological complexity is rooted in life history tradeoffs, in which beneficial change in one trait (e.g., fertility) is associated with a detrimental change in another (e.g., longevity). These tradeoffs are seen at all levels of biological organization, from single-celled and multicellular organisms to groups of cooperative individuals. However, queens of social insect colonies seem to escape such tradeoffs, as they are both long-lived and highly fertile while their workers are short-lived and rarely reproduce. There are two potential mechanisms for the decoupling of tradeoffs in social insect queens; (1) queens have greater access to resources and are, therefore, buffered from the costs of reproduction, (2) evolutionary rewiring of endocrine networks in social insects leads to a positive association between lifespan and fecundity. The facultatively social bee Megalopta genalis presents a unique opportunity to study the impact of fecundity and nutrition on life history traits, as females in the wild naturally vary in reproductive and nutritional states. We compared the immune responses of M. genalis in states of high and low reproduction (i.e. queens/solitary mothers and workers/newly emerged females) and high and low states of intrinsic resources (i.e. queens/lab-raised females and solitary mothers/workers). We find that, broadly, patterns of trade-off investment fluctuate depending on multiple factors. This tests whether trade-off investment is potentially influenced by cues at the environmental and evolutionary scale in this social insect.
