Evaluation of efficacy of insecticides against the fall army worm Spodoptera frugiperda.
The fall armyworm Spodoptera frugiperda (J.E. Smith) is an insect pest native to tropical and subtropical regions of the Americas, causing significant yield losses. The present study done in 2017 at the Amhara Region Agricultural Research Institute (ARARI) evaluates the efficacy of certain insecticides against this pest. A laboratory bioassay and field experiment were conducted with 14 insecticides along with an untreated check in a Complete Randomized Design replicated thrice. From the bioassay, the chi-square test revealed that chlorpyriphos ethyl, profenophos+ lambda cyhalothrin, profenophos+ cypermethrin, spinosad and indoxacarb were the best giving maximum larval mortality. In the field experiment, only profenophos+ cypermethrin and spinosad were effective giving maximum mortality of the sixth instar larva in the whorls; these were followed by profenophos+ lambda cyhalothrin and indoxacarb. Whorl application and spraying over the canopy had no significant difference. The results conclude that spraying over the canopy would be more effective against earlier larval instars since these could not hide in the whorl like those of the sixth instar.