Gut bacteria behind rotation-resistant rootworms
Researchers from the US University of Illinois (Urbana-Champaign) have found that the presence of specific gut bacteria species allow some western corn rootworms (Diabrotica virgifera virgifera) to survive crop rotation between maize and soybeans. Rotation-resistant populations of the rootworms developed some 20 years ago, and the trait is spreading. Analysis of gut micro-organisms in rotation-resistant rootworms showed that bacterially-produced enzymes improved the rootworm’s ability to digest soybean leaves and reduced the toxic effects of soybean plant defences. Overwintering adults were able to survive long enough to lay eggs that hatched in maize planted the following year. The study’s findings show that gut microbes are not just passive residents of the rootworm gut, but play an active part in insect adaptation, the researchers point out. Details of the study have been published in the journal, Proceedings of the National Academy of Sciences.