Susceptibility of tobacco thrips, Frankliniella fusca, to the neonicotinoid class of insecticides in Mid-South region

This paper will address reduced insecticidal efficacy of imidacloprid, thiamethoxam, and clothianidin against tobacco  thrips ,Frankliniella fusca (Hinds), in the Mid-Southern Region. Over the past several years tobacco thrips have become an increasing problem throughout the cotton cropping systems in the South. Thrips can cause a delay in maturity and cause a reduction in yield if not controlled. If infestations are severe, thrips can cause a loss of apical dominance or even kill plants. Currently, seed treatments are the primary means of controlling tobacco thrips in cotton. It is critical to understand the potential levels of resistance currently established in populations throughout the southern region of the U.S.

Dose-response bioassays with the three commonly used neonicotinoid insecticides were performed on field-collected adult female tobacco thrips during May and June, 2014. Populations were collected from agricultural regions in Mississippi from wild hosts as well as from insecticide-treated crops.  Results suggest that crop host was not an important factor in determining survival to neonicotinoids, but agricultural region was. Thrips collected from the Mississippi River Delta region were less susceptible to all three neonicotinoids than populations collected from the Northeastern part of Mississippi. When compared to a laboratory colony, field colonies were similarly susceptible to imidacloprid, but less susceptible to thiamethoxam.  Further research is planned to confirm findings and to explore the mechanisms that are responsible for resistance to these insecticides.