The ABCB multidrug resistance proteins do not contribute to ivermectin detoxification in the colorado potato beetle, leptinotarsa decemlineata (Say)

The Colorado potato beetle, a highly destructive agricultural pest with a global distribution, is typically controlled through the use of chemical insecticides. However, due to extensive exposure to such chemicals, this insect species has developed resistance to all products deployed against it, and investigating the mechanisms of insecticide detoxification in this pest is important for ensuring its continued control, since the same mechanisms may be contributors to such resistance. This study examined the potential role in insecticide detoxification by this beetle of a common protein family that often contributes to chemical resistance of cells, called the multidrug resistance proteins. To study such proteins, the genes encoding these membrane transporters were first characterized in the Colorado potato beetle genome and then the genes encoding them were silenced using a technique called RNA interference. Neither silencing the genes and thereby blocking production of the proteins, nor directly blocking the activity of the proteins with an inhibitor, had any impact on the effectiveness of a chemical insecticide (ivermectin) on the beetles. The results suggest that these proteins do not contribute to the insects’ ability to detoxify insecticide and therefore they are unlikely to be common contributors to the development of insecticide resistance in the Colorado potato beetle.