such as "Introduction", "Conclusion"..etc
March 9, 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.
Researchers have now shown 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".
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