Symbiotic partners vary in quality and availability in the environmentally acquired bug-Burkholderia symbiosis

Many species of true bugs in the Coreoidea and Lygaeoidea host Burkholderia bacteria within a specialized section of their midgut. These insects obtain important nutrients from the symbiont, yet they do not transmit it to their offspring. Instead, young nymphs must re-acquire the symbiont from the environment every generation. As a result, the insects can associate with many different strains and species of Burkholderia. We show that leaf-footed bugs (Leptoglossus, Coreidae) depend on Burkholderia for normal growth and development, and that different symbiont strains vary in quality: some strains promote higher host fitness than others. Fascinatingly, the benefits conferred by different strains are consistent across the congeneric bug species L. zonatus and L. phyllopus.

Next, we characterized Burkholderia strains in insects and soils along spatial transects in Arizona and California. We find that Burkholderia strain composition in soils turns over at the same spatial scale as it does in insects, suggesting that nymphs are limited by which microbial partners are available in their local environment. Future work will explore the costs and benefits associated with such geographically constrained symbiont acquisition: Are insects in the field at the mercy of environmental strain abundances? Or could wild insects benefit from context-dependent services provided by different Burkholderia strains?