Cells in broth are the most effective laboratory method for inoculation of leaf-footed bugs with symbiotic Caballeronia bacteria.

Hundreds of species of true bugs (Hemiptera) within the seed bugs, leaf-footed bugs, and allies (superfamilies Lygaeoidea and Coreoidea) depend on symbiotic Caballeronia bacteria which they must acquire from the environment every generation. There has been much recent interest in studying this symbiosis, in part because several of the insects that participate are agricultural pests, and in part because it is an interesting model system for understanding the environmental mode of symbiont acquisition. Researchers who want to rear and study these insects in captivity must ensure that the insects are successfully colonized by Caballeronia, but there is no standard method for doing so. We set out to assess five different methods of exposing insects to these bacteria. We tested the introduction of the bacteria via inoculated water, broth, plant sprig, potting soil, and uninoculated agricultural soil. No significant difference was seen between treatments in average adult weight or development time. However, the method of inoculation did affect the number of insects that reached adulthood. Insects exposed to agricultural soil and symbiont cells in water and were significantly less likely to reach adulthood than insects inoculated via cells in broth, on plant sprigs, or in potting soil. We therefore recommend use of inoculated broth as a simple and effective method to provide true bugs with their symbiotic Caballeronia in laboratory experiments. [ABSTRACT FROM AUTHOR]