The ABCB multidrug resistance proteins do not contribute to ivermectin detoxification in the colorado potato beetle, leptinotarsa decemlineata (Say)
Favell, G., McNeil, J.N., Donly, C. (2020). The ABCB multidrug resistance proteins do not contribute to ivermectin detoxification in the colorado potato beetle, leptinotarsa decemlineata (Say). Insects, [online] 11(2), http://dx.doi.org/10.3390/insects11020135
Plain language summary
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.
The Colorado potato beetle, Leptinotarsa decemlineata (Say), is a significant agricultural pest that has developed resistance to many insecticides that are used to control it. Investigating the mechanisms of insecticide detoxification in this pest is important for ensuring its continued control, since they may be contributors to such resistance. Multidrug resistance (MDR) genes that code for the ABCB transmembrane efflux transporters are one potential source of insecticide detoxification activity that have not been thoroughly examined in L. decemlineata. In this study, we annotated the ABCB genes found in the L. decemlineata genome and then characterized the expression profiles across midgut, nerve, and Malpighian tubule tissues of the three full transporters identified. To investigate if these genes are involved in defense against the macrocyclic lactone insecticide ivermectin in this insect, each gene was silenced using RNA interference or MDR protein activity was inhibited using a chemical inhibitor, verapamil, before challenging the insects with a dose of ivermectin. Survival of the insects did not significantly change due to gene silencing or protein inhibition, suggesting that MDR transporters do not significantly contribute to defense against ivermectin in L. decemlineata.