Abstract
Glass vials coated with several technical insecticides were used to determine the contact toxicity of insecticides on adult laboratory-reared and field-collected cotton fleahopper, Pseudatomoscelis seriatus (Reuter). For the 17 insecticides evaluated for laboratory-reared cotton fleahoppers, bifenthrin (pyrethroid), dicrotophos (organophosphate), thiamethoxam (neonicotinoid), and methomyl (carbamate) were the most toxic insecticides in their respective insecticidal classes based on LC50 values. There were significant differences between the LC50 values for the insecticides tested within each of the four insecticidal classes. There were 13-, 46-, 58-, and 31-fold differences between LC50 values for the insecticides within the pyrethroid, organophosphate, neonicotinoid, and carbarmate classes, respectively. Among fleahoppers collected from horsemint in May/June, adult vial testing showed increased susceptibility in males versus females. This difference can be attributed, at least in part, to differences in insect weights between the males and females since the females weighed significantly more than the males. Data presented herein provide a measure of acute potency of various insecticides against P. seriatus and serve as a measure of inherent relative differences between the insecticides. Baseline data will be useful for future comparison should suspicion of tolerance to these insecticides develop in field populations. These data are also important in comparing results from laboratory and field studies with cotton fleahoppers.
