Characterizing spatial distribution and host crop association of neonicotinoid resistant Frankliniella fusca (Thysanoptera: Thripidae)

Neonicotinoid seed treatments remain a critical management strategy to control Frankliniella fusca on seedling cotton in the Southeastern US. Since 2013, cotton growers throughout the region have reported greater than expected thrips damage on cotton seedlings that received an at-plant neonicotinoid seed treatment. In response to this issue, growers have adopted a series of prophylactic foliar applications in addition to the seed treatment to control insensitive F. fusca. Although the extent of resistance to neonicotinoids remains unknown growers continue to rely on additional insecticides for additive control. To document the extent of the problem, a diagnostic dose bioassay was used in 2014 and 2015 to establish the extent of neonicotinoid resistance in field-collected F. fusca populations in North Carolina. A nested, hierarchical sampling strategy was used to assess the spatial context of neonicotinoid resistance in cotton production regions of North Carolina. Spatial pattern analysis was used to characterize similarity in neonicotinoid response among F. fusca. Past crop production patterns in surrounding agroecosystems were also compared to determine if local grower practices that are commonly associated with neonicotinoid use are related to elevated levels of neonicotinoid insensitivity.