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Evaluation of Insecticide Resistance in Tobacco Thrips Populations and Plant Density Effects on Thrips Injury to Cotton
April 16 @ 10:30 am - 11:30 am EDT
In Tennessee, thrips rank among the top four insect pests of cotton, which is one of the top three cash crops grown in the state. Thrips management is necessary because their feeding injury can lead to delayed maturity and yield loss to cotton. This research will investigate two recent observations made in small-plot field trials in Tennessee. The first observation is that thrips injury seems greater in plots with a lower plant population, although research documenting this phenomenon is limited. Additionally, previous experiments in Tennessee indicate that tobacco thrips, Frankliniella fusca (Hinds), have become less sensitive to acephate, a common foliar-applied organophosphate (IRAC; MoA group 1B) insecticide used to control thrips. However, further research is needed to evaluate potential resistance to acephate in addition to the efficacy of other foliar-applied insecticides. Therefore, identical small-plot field trials with different planting densities were conducted in 2020 and will be repeated in 2021 at two locations in Tennessee. In 2020, the efficacy of foliar-applied insecticides was evaluated by performing standardized replicated field trials across the Mid-South and through bioassays conducted on Mid-South tobacco thrips populations. These studies will be repeated in 2021. Dose-response curves for acephate will be developed for at least one population from Tennessee thought to be resistant to acephate and another known susceptible population. The Tennessee population will also be selected for resistance to acephate for subsequent bioassays. All data will be analyzed using standard ANOVA/GLIMMIX procedures (SAS,9.4), and PROBIT procedures will be used to compare dose-response curves to acephate for selected thrips populations. This research will help growers in Tennessee decide how to use plant population and foliar-applied insecticides to manage thrips.