Bean Bugs & Burkholderia
The most intimate mutualism is the relationship between multicellular organisms and their microbiomes. The little ones look after their host.
The bean bug is an agricultural pest. Its prospects in a field sprayed with insecticide would be dim without a friend on the inside.
Bean bugs invariably ingest Burkholderia bacteria, which live in the dirt. Burkholderia have the happy knack of being able digest and disarm a commonly applied insecticide, thus saving the bean bug from terminal indigestion.