b'ROUNDTABLE Reducing the Colorado Potato Beetle ThreatNew research may help fight back against Colorado potato beetle resistance to protect potato crops.BY: ASHLEY ROBINSONHANNA MCCOY Editors note: This interview has been editeda high level of resistance to such a broad PhD candidate at thefor length and clarity. number of insecticides. University of NewOne thing we can do to not rely on Brunswick Spud Smart (SS): How doinsecticides alone is crop rotationso Colorado potato beetles (CPBs)thats really important. Where I sit in the become resistant to insecticides? Columbia Basin, generally, potatoes are Tim Waters (TW):Colorado potatogrown every one in three or one in four TIM WATERS beetles feed on the leaves of solanaceaeyears. It means that those beetles that persist plants. Solanaceae plants have highwithin that field dont get exposed to the professor/regional vegetable specialist andconcentrations of glycoalkaloids, whichsame insecticide year after year, the beetles Franklin County directormany species cannot digest because the toxichave to move to another field in order to find for Washington Statenature of those compounds. Its presumeda host. So, rotation is really important. University Extension that the evolution of Colorado potatoPhysical control is one option that helps. beetle to detoxify these glycoalkaloidsPotato beetles dont fly very much, they tend predispose them with mutations in theto walk from one host to the next. Physical population to easily detoxify pesticides.control with things like trenches can be Being multivotine, which means they havesomewhat effective on small plots but tend multiple generations per year and a highernot to work in large fields. reproductive rate, also predisposes them forAnother option is to alter planting the development of resistance.timing. We know that potato beetles come The more eggs that they have, the moreout of the ground pretty synchronously with likelihood that theres a genetic mutationnightshade plants. We can look at degree in there that can first resist itself. Withdays and if we have the flexibility, we could each female producing 600-plus eggs,avoid planting during that major emergence theres a good chance of that. In 1952, aperiod. You could delay planting a little population of CPBs developed resistancebit and that would help somewhat with to DDT, and then dieldrin in 1958. Sincethe Colorado potato beetle. The problem weve been using commercial pesticideswith that is if you delay planting too much, against Colorado potato beetle, theyvein some areas you dont have time to get been developing resistance. Almost allpotatoes to maturity or to the size that you insecticides introduced in the easternwant. Planting early is not a great option U.S. have populations of CPB that havebecause you put the plants at risk for fungal developed resistance very rapidly. or bacterial problems. SS: How can you manage orSS: When should growers apply reduce insecticide resistance ininsecticides for CPB control?CPBs? TW:Most insecticides for Colorado potato TW:The number one thing here is dobeetle control you want to time at 50 per not rely on insecticides alone. Relying oncent egg hatch. The best way to determine insecticides alone, like weve tended to dothat is by flipping over a lot of leaves and for the last 70 to 80 years is why weve seenthen looking at the colour of the eggs. potato beetle populations develop suchColour is not always a good character to 42SPUDSMART.COMWinter 2024'