Plants may induce "leaky gut syndrome" -- permeability of the gut lining -- in insects as part of a multipronged strategy for protecting themselves from being eaten, according to National Science Foundation researchers. By improving our understanding of plant defenses, the findings could contribute to the development of new pest control methods. The researchers reared fall armyworms in the laboratory and inoculated them with one of three types of naturally occurring gut bacteria. They fed the insects on one of three types of maize -- one that is known to express enzymes that produce perforations in insect gut linings; one that is characterized by numerous elongated trichomes, or fine hairs that occur on the surface of the plant and help defend against herbivores; and one that has just a few short trichomes. The team used scanning electron microscopy to evaluate the impacts of the various bacteria and maize types on the integrity of the fall armyworms' gut linings. The scientists found that the presence of all three types of gut bacteria decreased the ability of fall armyworm larvae to damage maize plants, especially when other defenses -- such as elongated trichomes and enzymes, both of which can perforate gut linings -- were present. However, the species of gut bacteria varied in the extent to which they weakened the insects.
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