Symbiotic Bacteria Results in Pest Insecticide Resistance

Post date:2018.03.19

A lot of gut flora (gut microbiota) including good and bad bacteria live in intestines of humans and animals. It has become clear that these bacteria are involved in the regulation of intestinal functions and are related to the immune system of hosts and infection.  Furthermore, brain-gut interaction which is an unexpected relationship between the brains feeling stress and the intestine has been also verified. In association with discovering these new systems, gut flora is attracting the attention as a new field of study. Now we would like to introduce symbiotic bacteria which belong to a pest that develops insecticide resistance to the pest itself.

Riptortus clavatus is a harmful soybean pest living in not only Japan and a wide areas of Asia. This pest takes Burkholderiales bacteria from circumstances of soil and lives together. Organophosphorus insecticide fenitrothion is used to kill Riptortus clavatus. Some soil bacteria were reported to decompose fenitrothion into a carbon source and use it for proliferation. Having isolated and examined Burkholderiales bacteria from Riptortus clavatus, bacteria which had decomposed fenitrothion were found in small amounts. Furthermore, it was clarified that Riptortus clavatus which had been infected by fenitrothion decomposing bacteria, significantly increased in resistance to fenitrothion, it indicates that the pest acquires resistance to the insecticide by living symbiotically with insecticide decomposing bacteria.

Until recently we have been thought that a host itself regulates its various characters. However, this study result broke the mold by indicating that characters of symbiotic bacteria living in the intestine reflected host’s characteristics. This report is a case of a pest and can’t be applied to mammals however, we feel the infinite possibilities of symbiotic bacteria (gut flora) which have been acquired in the process of evolution. Now, probiotics have been developed and actively applied, which might be a hint for idea of new efficacy.


Kikuchi Y, Hayatsu M, Hosokawa T, Nagayama A, Tago K, Fukatsu K: Symbiont-mediated insecticide resistance, Proc Natl Acad Sci USA, 109(22):8618-8622, 2012.