New research on bacterial endosymbionts in insects suggests that such bacteria may infect a wide variety of insect species but a low proportion of individuals within those species.
Insects have evolved a variety of mechanisms to try to overcome the effects of insecticides—including, in some cases, help from the bacteria and other microbes living in insects' guts. A growing number of studies indicate a link between symbiotic microbes and insecticide resistance in a diverse range of insects.
In cicadas, a world of microbes has evolved to provide them nutrients. Researchers at the University of Montana have discovered that a cicada bacterial endosymbiont, Hodgkinia cicadicola, has split into at least two dozen lineages within cicada cells, in an apparent case of nonadaptive evolution.