Resistance and cross-resistance to the spinosyns – A review and analysis

The spinosyns were introduced in 1997 with the launch of spinosad. Since then, there have been several cases of resistance to spinosad in the field populations of insect pest species that have resulted in reduced efficacy. There have also been a number of studies where spinosad-resistant insect strains were created and characterized in the laboratory. Likewise many studies examining resistance to a variety of other classes of insecticides have included spinosad in the evaluation of their cross-resistance spectrum. Understanding mechanisms of resistance and cross-resistance can provide the basis for developing insecticide resistance management programs, as well as defining the most appropriate tools to address potential resistance issues. This review provides an overview and analysis of resistance and cross-resistance to the spinosyns (spinosad and spinetoram). Although there are more than 30 examples of resistance to the spinosyns, only half of these are related to selection in the field. The majority of these field selected examples occur in either the diamondback moth or western flower thrips. There have also been over 85 studies investigating cross-resistance to the spinosyns. However, in half of these studies spinosad showed no cross-resistance, and in another third of the total studies spinosad cross-resistance was minimal. Therefore, while resistance and cross-resistance to the spinosyns does occur, it is appears to be more limited in impact than might be implied from the large body of literature on the subject.

Level of cross-resistance observed to the spinosyns across all species and studies n = 89.Figure optionsDownload as PowerPoint slideHighlights
► Introduced in 1997, spinosyns are used to control of a broad spectrum of insect pests.
► There are ∼30 examples of resistance to spinosyns, of which half are field-selected.
► Field selected resistance to spinosad has most commonly occurred in either diamondback moth or western flower thrips.
► In insects resistant to other insecticides, spinosyn cross-resistance is typically low/none.
► Resistance to the spinosyns appears to be mainly isolated to a few pest species.