Ensuring the Supply of French Fries by Examining a Beetle's Gut

Victoria Veldhoen
27 June 2012

Above: Colorado potato beetle (Fritz Geller-Grimm)

Did You Know? Larvae and adult Colorado potato beetles will strip a potato plant down to its stem.With the average Canadian consuming 13 kg of french fries every year, demand for potatoes remains strong. Unfortunately, potatoes and other popular vegetable crops are being ravaged by the Colorado potato beetle (also known as the “potato bug”). If this problem persists, Canadians might actually have to start ordering salads with their fast food, and no one wants that (to say nothing of world hunger)!

So how can the problem be solved? In the past, pesticides were an effective response to such pests. They did work well for a while, but ever since the potato bug became resistant to DDT in the 1950s, it has progressively developed resistance to newer and stronger pesticides.

Did You Know? Did you know that you can combat aphids and other pests in your own garden by ordering live insects online? A few clicks of the mouse and a supplier will have 1500 live ladybugs delivered to your door!Another strategy is to unleash one of the bug's natural predators. Much like how birds eat pesky mosquitoes, predators like the beetle Lebia grandis will happily devour the potato bug on our behalf. The main problem with this strategy lies in choosing the right predator. Choosing the wrong one can waste a significant amount of time and money.

One way of choosing the right predator is to perform gut content analysis on several candidates. This will help establish which one is consuming the potato bug most effectively. Matthew Greenstone, an entomologist at the Invasive Insect Biocontrol and Behaviour laboratory in Beltsville, Maryland, is doing exactly that with the help of DNA barcoding. Each species has its own specific DNA tag or “barcode,” so examining the DNA present in a predator's gut will show exactly which species it has consumed.

Did You Know? Larvae and adult Colorado potato beetles will strip a potato plant down to its stem!By studying the DNA barcode of predator’s stomach contents, as well as other factors such as digestion rate and insecticide susceptibility, scientists can better combat the Colorado potato beetle and similar pests.

Learn More! Barcoding Insects to Control Them (Dennis O'Brien in Agricultural Research)

http://www.ars.usda.gov/is/AR/archive/apr12/insects0412.pdf

Victoria Veldhoen

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