Bad Bugs: Cigarette Beetle

By Pat Kelley, ACE

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Cigarette beetles can digest toxic plant material like tobacco with the help of internal organisms.

Stored product pests never cease to amaze me with the physical traits and abilities they have acquired over evolutionary time. A female granary weevil with her long snout can bore a hole into a kernel of wheat and then turn on a dime and drop an egg into the hole from the tip of her abdomen without even looking. Indianmeal moth larvae can completely cover the dried food goods they are eating with a thick layer of webbing to create their own micro-environments. One of the most mind-boggling traits to me though is the symbiotic relationship that the stored-product pest, Cigarette beetle, Lasioderma serricorne has with yeast-like organisms in its guts. These organisms allow cigarette beetles to digest toxic plant materials like tobacco and go unharmed. If you didn’t already know, nicotine can be considered a pesticide and is present in the dried leaves of tobacco. So just how can Cigarette beetles pull off eating such a toxic meal? Well, from a scientific perspective, the digestive tract of the Cigarette beetle has small organ-like structures called mycetomes. Housed in these mycetomes are yeast-like organisms that will eat and de-toxify the tobacco leaf after the cigarette beetle larva has ingested it. The yeast-like organisms benefit by having a food supply brought right to them from the beetle larva and the larva benefits by not being killed from the nicotine and gaining valuable nutrition from an otherwise inedible food source. Termites, powderpost beetles and carpet beetles have similar organisms to help them digest things like wood and keratin in wool. The insect species and their internal companions make sure that their relationship continues as the female insect will pass along a few organisms from her ovaries to the egg she lays. And so the story goes as our pesty little friends continue to eat our tobacco, wool, and wood right out from under us. Just remember that in this case, it is the beast within the bug that makes it all work out.

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