Susceptibility of western corn rootworm (Coleoptera: Chrysomelidae) to tefluthrin

Corn (Zea maize) is the primary agricultural crop in the United States, with around 80 million acres planted every year. Diabrotica virgifera virgifera (LeConte, 1868), the western corn rootworm, is the most important economic pest of corn. Among the insecticides used to control the western corn rootworm, tefluthrin, a contact synthetic pyrethroid is widely used. In order to determine the LC₅₀, neonates from eight different laboratory populations were exposed to filter paper treated with a range of tefluthrin concentrations and mortality was recorded after 24h. The obtained LC₅₀’s will be used to establish a baseline that can be compared with the LC₅₀ of field populations that will be collected during the summer of 2013. The field populations will be expected to have different values for LC₅₀ and higher than those found for the laboratory populations if they have experienced significant selection. Such differences could be explained by previous extensive exposure of field populations to tefluthrin. Tolerant individuals might be selected through several generations of exposure. Over time, tolerant individuals in addition to natural selection may generate a resistant population what will confer important implications to pest management of this pest.