Insecticidal toxin useless without 'friendly' bacteria accomplices

Mar 04, 2009

The toxin produced by the bacterium Bacillus thuringiensis (Bt) is a popular insecticide used to control pest moths and butterflies, and in some GM pest-proof crops. In a study published in the open access journal BMC Biology, researchers show that its effectiveness against a number of susceptible Lepidopteran species depends on the presence of the normally "friendly" bacteria that colonise their guts. Without these bacteria, the Bt toxin can become impotent in some species.

A team of researchers from the University of Wisconsin studied the effects of wiping out the commensal gut bacteria using antibiotics in six moth and butterfly species. In five of these species, the antibiotic treatment protected the insects against the lethal effects of the toxin, and in four of the five species, replacing the gut bacteria caused the toxin to become effective again. Graduate student Nichole Broderick said, "Our results suggest that Bt may kill some insects by causing otherwise benign gut bacteria to exert pathogenic effects. If the insects don't have these bacteria present, the toxin may be ineffective".

According to the authors, "We've shown that larval enteric bacteria affect susceptibility to Bt, and the extent of this impact varies across butterfly and moth species. This does not exclude other factors, including the insect host, B. thuringiensis strain, and environmental conditions. In some cases these factors may interact, for example, host diet can alter the composition of enteric bacteria".

They conclude, "From a pest management perspective, the ability of a non-specific enteric bacterium to restore B. thuringiensis-induced mortality of some Lepidopteran species may provide opportunities for increasing susceptibility or preventing resistance".

More information: Contributions of gut bacteria to Bacillus thuringiensis-induced mortality vary across a range of Lepidoptera, Nichole A. Broderick, Courtney J. Robinson, Matthew D. McMahon, Jonathan Holt, Jo Handelsman and Kenneth F. Raffa, BMC Biology (in press)
Article available at journal website: www.biomedcentral.com/bmcbiol/

Source: BioMed Central

Explore further: 'Office life' of bacteria may be their weak spot

add to favorites email to friend print save as pdf

Related Stories

Fecal transplants let packrats eat poison

Jul 21, 2014

Woodrats lost their ability to eat toxic creosote bushes after antibiotics killed their gut microbes. Woodrats that never ate the plants were able to do so after receiving fecal transplants with microbes ...

Bees from the inside out

Jul 08, 2014

It is 1,825 miles from New Haven, Conn., to Austin, Tex., which typically means 30 hours of driving and three nights in motels, not an easy trip for anyone. But for researchers moving from Yale University ...

Recommended for you

Healthy humans make nice homes for viruses

Sep 16, 2014

The same viruses that make us sick can take up residence in and on the human body without provoking a sneeze, cough or other troublesome symptom, according to new research at Washington University School ...

Unraveling cell division

Sep 16, 2014

CRG researchers shed new light on mitosis. The study published in the Journal of Cell Biology describes how Topo 2 disentangles DNA molecules and is essential for proper cell division

User comments : 0