Predicting Resurgence of Western Flower Thrips (Thysanoptera: Thripidae) on Onions After Insecticide Application in the Texas High Plains

Abstract

Population resurgence of western flower thrips, Frankliniella occidentalis (Pergande), was observed on onions after insecticide application during two growing seasons on the Texas High Plains. Regression models were used to quantify variables influencing western flower thrips population dynamics. Thrips densities increased exponentially after being sprayed with insecticide. This resurgence was aided by degree-days (DD) between thresholds of 5 and 35°C accumulated after insecticide application, whereas accumulated DD above a threshold of 35°C greatly hindered increase. Density of western flower thrips on onions was predicted by DD and rainfall accumulations.