In a recent post, I highlighted the Buchnera symbionts of some aphids. Ten percent of insect species are known to require microbes that provide some of the nutritional requirements. In a recent paper in Science, Molly Hunter’s group at Arizona describes the rapid development of a symbiotic relationship between a whitefly and a rickettsia bacteria.
The sweet potato whitefly, Bemesia tabasci, is a pest of vegetables and greenhouse plants. In about 6 years, the Arizona populations of Bemesia went from close to zero percent infection with Rickettsia to over 90 percent infection. The Ricekttsia infected whiteflies produced more offspring and grew faster than the uninfected whiteflies.
Insects that feed on plant phloem obtain excess sugar, but are lacking in other nutrients. Symbionts can supply the missing nutrients and benefit the aphid. In return, the symbionts get a stable, protective environment and access to all the sugar they need for their growth and reproduction.
It seems unusual that a bacteria could move into a species with mostly positive consequences and few notable negative consequences in such as short period of time. More typically, bacteria and their hosts have some negative interactions that must be overcome through coevolution of adaptations. Symbionts are critical for many animals. As our research tools improve, we learn more about these amazing interactions.