Aphids, including soybean aphid, are known for for their association with an obligate symbiont, Buchnera aphidicola. The Buchnera are housed in special aphid cells and transmitted from female aphids to her offspring. Aphids do not survive without the essential amino acids and other nutrients contributed by Buchnera.
The soybean aphid houses additional bacteria including Arsenophonus which is not required but has been found in an overwhelming majority of soybean aphids tested*….
Source: Living With Insects Blog